% -*- Mode: TeX -*- \def\GFauxOptionsAndMethDesc{ \auxbnf{option}{\paren{\kwd{argument-precedence-order} \plusparam{parameter-name}} | \CR \paren{\misc{declare} \plusparam{declaration}} | \CR \paren{\kwd{documentation} \i{string}} | \CR \paren{\kwd{method-combination} \i{symbol} \starparam{arg}} | \CR \paren{\kwd{generic-function-class} \i{class-name}} | \CR \paren{\kwd{method-class} \i{class-name}}} \auxbnf{method-description}{\lparen\kwd{method} \CR \ \starparam{method-qualifier} specialized-lambda-list \CR \ {\DeclsAndDoc} \CR \ \starparam{form}\rparen} } %%% ========== FUNCTION-KEYWORDS \begincom{function-keywords}\ftype{Standard Generic Function} %Barmar: This function should have been called ``method-keywords.'' \label Syntax:: \DefgenWithValues {function-keywords} {method} {keys, allow-other-keys-p} \label Method Signatures:: \Defmeth {function-keywords} {\specparam{method}{standard-method}} \label Arguments and Values:: \param{method}---a \term{method}. \param{keys}---a \term{list}. \param{allow-other-keys-p}---a \term{generalized boolean}. \label Description:: Returns the keyword parameter specifiers for a \param{method}. Two values are returned: a \term{list} of the explicitly named keywords and a \term{generalized boolean} that states whether \keyref{allow-other-keys} had been specified in the \param{method} definition. \label Examples:: \code (defmethod gf1 ((a integer) &optional (b 2) &key (c 3) ((:dee d) 4) e ((eff f))) (list a b c d e f)) \EV # (find-method #'gf1 '() (list (find-class 'integer))) \EV # (function-keywords *) \EV (:C :DEE :E EFF), \term{false} (defmethod gf2 ((a integer)) (list a b c d e f)) \EV # (function-keywords (find-method #'gf1 '() (list (find-class 'integer)))) \EV (), \term{false} (defmethod gf3 ((a integer) &key b c d &allow-other-keys) (list a b c d e f)) (function-keywords *) \EV (:B :C :D), \term{true} \endcode \label Affected By:: \macref{defmethod} \label Exceptional Situations:\None. \label See Also:: \macref{defmethod} \label Notes:\None. \endcom %%% ========== ENSURE-GENERIC-FUNCTION \begincom{ensure-generic-function}\ftype{Function} \label Syntax:: \DefunWithValuesNewline ensure-generic-function {function-name {\key} \vtop{\hbox{argument-precedence-order declare} \hbox{documentation environment} \hbox{generic-function-class lambda-list} \hbox{method-class method-combination}}} {generic-function} \label Arguments and Values:: \param{function-name}---a \term{function name}. The keyword arguments correspond to the \param{option} arguments of \macref{defgeneric}, except that the \kwd{method-class} and \kwd{generic-function-class} arguments can be \term{class} \term{object}s as well as names. %!!! What's a method combination object?? {\keyword Method-combination} -- method combination object. {\keyword Environment} -- the same as the \keyref{environment} argument to macro expansion functions and is used to distinguish between compile-time and run-time environments. %Barmar said (and I agree) that this just doesn't belong here. % \issue{MACRO-ENVIRONMENT-EXTENT:DYNAMIC} % The \keyref{environment} argument has % \term{dynamic extent}; the consequences are undefined if % the \keyref{environment} argument is % referred to outside the \term{dynamic extent} % of the macro expansion function. % \endissue{MACRO-ENVIRONMENT-EXTENT:DYNAMIC} \editornote{KMP: What about documentation. Missing from this arguments enumeration, and confusing in description below.}%!!! \param{generic-function}---a \term{generic function} \term{object}. \label Description:: \Thefunction{ensure-generic-function} is used to define a globally named \term{generic function} with no \term{methods} or to specify or modify options and declarations that pertain to a globally named \term{generic function} as a whole. %!!! This used to refer to FBOUNDP but I changed it to use "fbound". % The question is, why is it looking in the global env if an environment % argument was passed. If \param{function-name} is not \term{fbound} in the \term{global environment}, a new \term{generic function} is created. %!!! Rewrite in terms of function cell contents? If \issue{FUNCTION-NAME:LARGE} \f{(fdefinition \param{function-name})} \endissue{FUNCTION-NAME:LARGE} is an \term{ordinary function}, a \term{macro}, or a \term{special operator}, an error is signaled. If \param{function-name} is a \term{list}, it must be of the form \f{(setf \param{symbol})}. If \param{function-name} specifies a \term{generic function} that has a different value for any of the following arguments, the \term{generic function} is modified to have the new value: \kwd{argument-precedence-order}, \kwd{declare}, \kwd{documentation}, \kwd{method-combination}. If \param{function-name} specifies a \term{generic function} that has a different value for the \kwd{lambda-list} argument, and the new value is congruent with the \term{lambda lists} of all existing \term{methods} or there are no \term{methods}, the value is changed; otherwise an error is signaled. %!!! Barmar: What does this part about % "new generic function class is compatible with the old" mean? If \param{function-name} specifies a \term{generic function} that has a different value for the \kwd{generic-function-class} argument and if the new generic function class is compatible with the old, \funref{change-class} is called to change the \term{class} of the \term{generic function}; otherwise an error is signaled. If \param{function-name} specifies a \term{generic function} that has a different value for the \kwd{method-class} argument, the value is changed, but any existing \term{methods} are not changed. \label Examples:\None. \label Affected By:: Existing function binding of \param{function-name}. \label Exceptional Situations:: If \issue{FUNCTION-NAME:LARGE} \f{(fdefinition \param{function-name})} \endissue{FUNCTION-NAME:LARGE} is an \term{ordinary function}, a \term{macro}, or a \term{special operator}, an error \oftype{error} is signaled. If \param{function-name} specifies a \term{generic function} that has a different value for the \kwd{lambda-list} argument, and the new value is not congruent with the \term{lambda list} of any existing \term{method}, an error \oftype{error} is signaled. If \param{function-name} specifies a \term{generic function} that has a different value for the \kwd{generic-function-class} argument and if the new generic function class not is compatible with the old, an error \oftype{error} is signaled. \label See Also:: \macref{defgeneric} \label Notes:\None. \endcom %%% ========== ALLOCATE-INSTANCE \begincom{allocate-instance}\ftype{Standard Generic Function} \issue{ALLOCATE-INSTANCE:ADD} \label Syntax:: \issue{INITIALIZATION-FUNCTION-KEYWORD-CHECKING} \DefgenWithValues allocate-instance {class {\rest} initargs {\key} {\allowotherkeys}} {new-instance} \endissue{INITIALIZATION-FUNCTION-KEYWORD-CHECKING} \label Method Signatures:: \Defmeth {allocate-instance} {\specparam{class}{standard-class} {\rest} initargs} \Defmeth {allocate-instance} {\specparam{class}{structure-class} {\rest} initargs} \label Arguments and Values:: \param{class}---a \term{class}. \param{initargs}---a \term{list} of \term{keyword/value pairs} (initialization argument \term{names} and \term{values}). \param{new-instance}---an \term{object} whose \term{class} is \param{class}. \label Description:: The generic function \funref{allocate-instance} creates and returns a new instance of the \param{class}, without initializing it. When the \param{class} is a \term{standard class}, this means that the \term{slots} are \term{unbound}; when the \term{class} is a \term{structure class}, this means the \term{slots}' \term{values} are unspecified. The caller of \funref{allocate-instance} is expected to have already checked the initialization arguments. The \term{generic function} \funref{allocate-instance} is called by \funref{make-instance}, as described in \secref\ObjectCreationAndInit. \label Affected By:\None. % ???? \label Exceptional Situations:\None. % ???? \label See Also:: \macref{defclass}, \funref{make-instance}, \funref{class-of}, {\secref\ObjectCreationAndInit} \label Notes:: The consequences of adding \term{methods} to \funref{allocate-instance} is unspecified. This capability might be added by the \term{Metaobject Protocol}. % kmp: This section was copied with minor changes from % \funref{make-instance}, and then reviewed by Moon. \endissue{ALLOCATE-INSTANCE:ADD} \endcom %%% ========== REINITIALIZE-INSTANCE \begincom{reinitialize-instance}\ftype{Standard Generic Function} \label Syntax:: \issue{INITIALIZATION-FUNCTION-KEYWORD-CHECKING} \DefgenWithValues reinitialize-instance {instance {\rest} initargs {\key} {\allowotherkeys}} {instance} \endissue{INITIALIZATION-FUNCTION-KEYWORD-CHECKING} \label Method Signatures:: \Defmeth reinitialize-instance {\specparam{instance}{standard-object} {\rest} initargs} \label Arguments and Values:: \param{instance}---an \term{object}. \param{initargs}---an \term{initialization argument list}. \label Description:: The \term{generic function} \funref{reinitialize-instance} can be used to change the values of \term{local slots} of an \param{instance} according to \param{initargs}. %This generic function is called by the Meta-Object %Protocol. This \term{generic function} can be called by users. The system-supplied primary \term{method} for \funref{reinitialize-instance} checks the validity of \param{initargs} and signals an error if an \param{initarg} is supplied that is not declared as valid. The \term{method} then calls the generic function \funref{shared-initialize} with the following arguments: the \param{instance}, \nil\ (which means no \term{slots} should be initialized according to their initforms), and the \param{initargs} it received. \label Examples:\None. \label Side Effects:: \TheGF{reinitialize-instance} changes the values of \term{local slots}. \label Affected By:\None. \label Exceptional Situations:: The system-supplied primary \term{method} for \funref{reinitialize-instance} signals an error if an \param{initarg} is supplied that is not declared as valid. \label See Also:: \funref{initialize-instance}, \funref{shared-initialize}, \funref{update-instance-for-redefined-class}, \funref{update-instance-for-different-class}, \funref{slot-boundp}, \funref{slot-makunbound}, {\secref\InstanceReInit}, {\secref\InitargRules}, {\secref\DeclaringInitargValidity} \label Notes:: \param{Initargs} are declared as valid by using the \kwd{initarg} option to \macref{defclass}, or by defining \term{methods} for \funref{reinitialize-instance} or \funref{shared-initialize}. The keyword name of each keyword parameter specifier in the \term{lambda list} of any \term{method} defined on \funref{reinitialize-instance} or \funref{shared-initialize} is declared as a valid initialization argument name for all \term{classes} for which that \term{method} is applicable. \endcom %%% ========== SHARED-INITIALIZE \begincom{shared-initialize}\ftype{Standard Generic Function} \label Syntax:: \issue{INITIALIZATION-FUNCTION-KEYWORD-CHECKING} \DefgenWithValues shared-initialize {instance slot-names {\rest} initargs {\key} {\allowotherkeys}} {instance} \endissue{INITIALIZATION-FUNCTION-KEYWORD-CHECKING} \label Method Signatures:: \Defmeth shared-initialize {\specparam{instance}{standard-object} slot-names {\rest} initargs} \label Arguments and Values:: \param{instance}---an \term{object}. \param{slot-names}---a \term{list} or \t. \param{initargs}---a \term{list} of \term{keyword/value pairs} (of initialization argument \term{names} and \term{values}). \label Description:: The generic function \funref{shared-initialize} is used to fill the \term{slots} of an \param{instance} using \param{initargs} and \kwd{initform} forms. It is called when an instance is created, when an instance is re-initialized, when an instance is updated to conform to a redefined \term{class}, and when an instance is updated to conform to a different \term{class}. The generic function \funref{shared-initialize} is called by the system-supplied primary \term{method} for \funref{initialize-instance}, \funref{reinitialize-instance}, \funref{update-instance-for-redefined-class}, and \funref{update-instance-for-different-class}. The generic function \funref{shared-initialize} takes the following arguments: the \param{instance} to be initialized, a specification of a set of \param{slot-names} \term{accessible} in that \param{instance}, and any number of \param{initargs}. The arguments after the first two must form an \term{initialization argument list}. The system-supplied primary \term{method} on \funref{shared-initialize} initializes the \term{slots} with values according to the \param{initargs} and supplied \kwd{initform} forms. \param{Slot-names} indicates which \term{slots} should be initialized according to their \kwd{initform} forms if no \param{initargs} are provided for those \term{slots}. The system-supplied primary \term{method} behaves as follows, regardless of whether the \term{slots} are local or shared: \beginlist \itemitem{\bull} If an \param{initarg} in the \term{initialization argument list} specifies a value for that \term{slot}, that value is stored into the \term{slot}, even if a value has already been stored in the \term{slot} before the \term{method} is run. \itemitem{\bull} Any \term{slots} indicated by \param{slot-names} that are still unbound at this point are initialized according to their \kwd{initform} forms. For any such \term{slot} that has an \kwd{initform} form, that \term{form} is evaluated in the lexical environment of its defining \macref{defclass} \term{form} and the result is stored into the \term{slot}. For example, if a \term{before method} stores a value in the \term{slot}, the \kwd{initform} form will not be used to supply a value for the \term{slot}. \itemitem{\bull} The rules mentioned in {\secref\InitargRules} are obeyed. \endlist The \param{slots-names} argument specifies the \term{slots} that are to be initialized according to their \kwd{initform} forms if no initialization arguments apply. It can be a \term{list} of slot \term{names}, which specifies the set of those slot \term{names}; or it can be the \term{symbol} \t, which specifies the set of all of the \term{slots}. %The generic function \funref{shared-initialize} fills the \term{slots} %of \param{instance}. \label Examples:\None. \label Affected By:\None. \label Exceptional Situations:\None. %% Removed per X3J13. -kmp 5-Oct-93 % An error \oftype{error} is signaled if an \param{initarg} % is supplied that is not declared as valid. \label See Also:: \funref{initialize-instance}, \funref{reinitialize-instance}, \funref{update-instance-for-redefined-class}, \funref{update-instance-for-different-class}, \funref{slot-boundp}, \funref{slot-makunbound}, {\secref\ObjectCreationAndInit}, {\secref\InitargRules}, {\secref\DeclaringInitargValidity} \label Notes:: \param{Initargs} are declared as valid by using the \kwd{initarg} option to \macref{defclass}, or by defining \term{methods} for \funref{shared-initialize}. The keyword name of each keyword parameter specifier in the \term{lambda list} of any \term{method} defined on \funref{shared-initialize} is declared as a valid \param{initarg} name for all \term{classes} for which that \term{method} is applicable. Implementations are permitted to optimize \kwd{initform} forms that neither produce nor depend on side effects, by evaluating these \term{forms} and storing them into slots before running any \funref{initialize-instance} methods, rather than by handling them in the primary \funref{initialize-instance} method. (This optimization might be implemented by having the \funref{allocate-instance} method copy a prototype instance.) Implementations are permitted to optimize default initial value forms for \param{initargs} associated with slots by not actually creating the complete initialization argument \term{list} when the only \term{method} that would receive the complete \term{list} is the \term{method} on \typeref{standard-object}. In this case default initial value forms can be treated like \kwd{initform} forms. This optimization has no visible effects other than a performance improvement. \endcom %%% ========== UPDATE-INSTANCE-FOR-DIFFERENT-CLASS \begincom{update-instance-for-different-class}\ftype{Standard Generic Function} \label Syntax:: \issue{INITIALIZATION-FUNCTION-KEYWORD-CHECKING} \DefgenWithValues update-instance-for-different-class {previous current {\rest} initargs {\key} {\allowotherkeys}} {\term{implementation-dependent}} \endissue{INITIALIZATION-FUNCTION-KEYWORD-CHECKING} \label Method Signatures:: \Defmeth {update-instance-for-different-class} {\vtop{\hbox{\specparam{previous}{standard-object}} \hbox{\specparam{current}{standard-object}} \hbox{{\rest} initargs}}} \label Arguments and Values:: \param{previous}---a copy of the original \term{instance}. \param{current}---the original \term{instance} (altered). \param{initargs}---an \term{initialization argument list}. \label Description:: The generic function \funref{update-instance-for-different-class} is not intended to be called by programmers. Programmers may write \term{methods} for it. \Thefunction{update-instance-for-different-class} is called only by \thefunction{change-class}. The system-supplied primary \term{method} on \funref{update-instance-for-different-class} checks the validity of \param{initargs} and signals an error if an \param{initarg} is supplied that is not declared as valid. This \term{method} then initializes \term{slots} with values according to the \param{initargs}, and initializes the newly added \term{slots} with values according to their \kwd{initform} forms. It does this by calling the generic function \funref{shared-initialize} with the following arguments: the instance (\param{current}), a list of \term{names} of the newly added \term{slots}, and the \param{initargs} it received. Newly added \term{slots} are those \term{local slots} for which no \term{slot} of the same name exists in the \param{previous} class. \term{Methods} for \funref{update-instance-for-different-class} can be defined to specify actions to be taken when an \term{instance} is updated. If only \term{after methods} for \funref{update-instance-for-different-class} are defined, they will be run after the system-supplied primary \term{method} for initialization and therefore will not interfere with the default behavior of \funref{update-instance-for-different-class}. \term{Methods} on \funref{update-instance-for-different-class} can be defined to initialize \term{slots} differently from \funref{change-class}. The default behavior of \funref{change-class} is described in \secref\ChangingInstanceClass. The arguments to \funref{update-instance-for-different-class} are computed by \funref{change-class}. When \funref{change-class} is invoked on an \term{instance}, a copy of that \term{instance} is made; \funref{change-class} then destructively alters the original \term{instance}. The first argument to \funref{update-instance-for-different-class}, \param{previous}, is that copy; it holds the old \term{slot} values temporarily. This argument has dynamic extent within \funref{change-class}; if it is referenced in any way once \funref{update-instance-for-different-class} returns, the results are undefined. The second argument to \funref{update-instance-for-different-class}, \param{current}, is the altered original \term{instance}. The intended use of \param{previous} is to extract old \term{slot} values by using \funref{slot-value} or \macref{with-slots} or by invoking a reader generic function, or to run other \term{methods} that were applicable to \term{instances} of the original \term{class}. %The system-supplied primary \term{method} on %\funref{update-instance-for-different-class} %initializes \term{slots} with values according to the initialization %arguments, and initializes the newly added \term{slots} with values according %to their \kwd{initform} forms. \label Examples:: See the example for \thefunction{change-class}. \label Affected By:\None. \label Exceptional Situations:: The system-supplied primary \term{method} on \funref{update-instance-for-different-class} signals an error if an initialization argument is supplied that is not declared as valid. \label See Also:: \funref{change-class}, \funref{shared-initialize}, {\secref\ChangingInstanceClass}, {\secref\InitargRules}, {\secref\DeclaringInitargValidity} \label Notes:: \param{Initargs} are declared as valid by using the \kwd{initarg} option to \macref{defclass}, or by defining \term{methods} for \funref{update-instance-for-different-class} or \funref{shared-initialize}. The keyword name of each keyword parameter specifier in the \term{lambda list} of any \term{method} defined on \funref{update-instance-for-different-class} or \funref{shared-initialize} is declared as a valid \param{initarg} name for all \term{classes} for which that \term{method} is applicable. The value returned by \funref{update-instance-for-different-class} is ignored by \funref{change-class}. \endcom %%% ========== UPDATE-INSTANCE-FOR-REDEFINED-CLASS \begincom{update-instance-for-redefined-class}\ftype{Standard Generic Function} \label Syntax:: \issue{INITIALIZATION-FUNCTION-KEYWORD-CHECKING} \DefgenWithValuesNewline update-instance-for-redefined-class {\vtop{\hbox{instance} \hbox{added-slots discarded-slots} \hbox{property-list} \hbox{{\rest} initargs {\key} {\allowotherkeys}}}} {\starparam{result}} \endissue{INITIALIZATION-FUNCTION-KEYWORD-CHECKING} \label Method Signatures:: \Defmeth {update-instance-for-redefined-class} {\vtop{\hbox{\specparam{instance}{standard-object}} \hbox{added-slots discarded-slots} \hbox{property-list} \hbox{{\rest} initargs}}} \label Arguments and Values:: \param{instance}---an \term{object}. \param{added-slots}---a \term{list}. \param{discarded-slots}---a \term{list}. \param{property-list}---a \term{list}. \param{initargs}---an \term{initialization argument list}. \param{result}---an \term{object}. \label Description:: The \term{generic function} \funref{update-instance-for-redefined-class} is not intended to be called by programmers. Programmers may write \term{methods} for it. The \term{generic function} \funref{update-instance-for-redefined-class} is called by the mechanism activated by \funref{make-instances-obsolete}. The system-supplied primary \term{method} on \funref{update-instance-for-redefined-class} checks the validity of \param{initargs} and signals an error if an \param{initarg} is supplied that is not declared as valid. This \term{method} then initializes \term{slots} with values according to the \param{initargs}, and initializes the newly \param{added-slots} with values according to their \kwd{initform} forms. It does this by calling the generic function \funref{shared-initialize} with the following arguments: the \param{instance}, a list of names of the newly \param{added-slots} to \param{instance}, and the \param{initargs} it received. Newly \param{added-slots} are those \term{local slots} for which no \term{slot} of the same name exists in the old version of the \term{class}. When \funref{make-instances-obsolete} is invoked or when a \term{class} has been redefined and an \term{instance} is being updated, a \param{property-list} is created that captures the slot names and values of all the \param{discarded-slots} with values in the original \param{instance}. The structure of the \param{instance} is transformed so that it conforms to the current class definition. The arguments to \funref{update-instance-for-redefined-class} are this transformed \param{instance}, a list of \param{added-slots} to the \param{instance}, a list \param{discarded-slots} from the \param{instance}, and the \param{property-list} containing the slot names and values for \term{slots} that were discarded and had values. Included in this list of discarded \term{slots} are \term{slots} that were local in the old \term{class} and are shared in the new \term{class}. %The system-supplied primary \term{method} on %\funref{update-instance-for-redefined-class} %initializes \term{slots} with values according to the \param{initargs}, %and initializes the newly \param{added-slots} with values according %to their \kwd{initform} forms. It does this by calling the generic %function \funref{shared-initialize}. %!!! So? The value returned by \funref{update-instance-for-redefined-class} is ignored. \label Examples:: \code (defclass position () ()) (defclass x-y-position (position) ((x :initform 0 :accessor position-x) (y :initform 0 :accessor position-y))) ;;; It turns out polar coordinates are used more than Cartesian ;;; coordinates, so the representation is altered and some new ;;; accessor methods are added. (defmethod update-instance-for-redefined-class :before ((pos x-y-position) added deleted plist &key) ;; Transform the x-y coordinates to polar coordinates ;; and store into the new slots. (let ((x (getf plist 'x)) (y (getf plist 'y))) (setf (position-rho pos) (sqrt (+ (* x x) (* y y))) (position-theta pos) (atan y x)))) (defclass x-y-position (position) ((rho :initform 0 :accessor position-rho) (theta :initform 0 :accessor position-theta))) ;;; All instances of the old x-y-position class will be updated ;;; automatically. ;;; The new representation is given the look and feel of the old one. (defmethod position-x ((pos x-y-position)) (with-slots (rho theta) pos (* rho (cos theta)))) (defmethod (setf position-x) (new-x (pos x-y-position)) (with-slots (rho theta) pos (let ((y (position-y pos))) (setq rho (sqrt (+ (* new-x new-x) (* y y))) theta (atan y new-x)) new-x))) (defmethod position-y ((pos x-y-position)) (with-slots (rho theta) pos (* rho (sin theta)))) (defmethod (setf position-y) (new-y (pos x-y-position)) (with-slots (rho theta) pos (let ((x (position-x pos))) (setq rho (sqrt (+ (* x x) (* new-y new-y))) theta (atan new-y x)) new-y))) \endcode \label Affected By:\None. \label Exceptional Situations:: The system-supplied primary \term{method} on \funref{update-instance-for-redefined-class} signals an error if an \param{initarg} is supplied that is not declared as valid. \label See Also:: \funref{make-instances-obsolete}, \funref{shared-initialize}, {\secref\ClassReDef}, {\secref\InitargRules}, {\secref\DeclaringInitargValidity} \label Notes:: \param{Initargs} are declared as valid by using the \kwd{initarg} option to \macref{defclass}, or by defining \term{methods} for \funref{update-instance-for-redefined-class} or \funref{shared-initialize}. The keyword name of each keyword parameter specifier in the \term{lambda list} of any \term{method} defined on \funref{update-instance-for-redefined-class} or \funref{shared-initialize} is declared as a valid \param{initarg} name for all \term{classes} for which that \term{method} is applicable. \endcom %%% ========== CHANGE-CLASS \begincom{change-class}\ftype{Standard Generic Function} \label Syntax:: \issue{CHANGE-CLASS-INITARGS:PERMIT} \DefgenWithValues change-class {instance new-class {\key} {\allowotherkeys}} {instance} \endissue{CHANGE-CLASS-INITARGS:PERMIT} \label Method Signatures:: \issue{CHANGE-CLASS-INITARGS:PERMIT} \Defmeth {change-class} {\specparam{instance}{standard-object} \specparam{new-class}{standard-class} {\rest} initargs} \Defmeth {change-class} {\specparam{instance}{t} \specparam{new-class}{symbol} {\rest} initargs} \endissue{CHANGE-CLASS-INITARGS:PERMIT} \label Arguments and Values:: \param{instance}---an \term{object}. \param{new-class}---a \term{class designator}. \issue{CHANGE-CLASS-INITARGS:PERMIT} \param{initargs}---an \term{initialization argument list}. \endissue{CHANGE-CLASS-INITARGS:PERMIT} \label Description:: The \term{generic function} \funref{change-class} changes the \term{class} of an \param{instance} to \param{new-class}. It destructively modifies and returns the \param{instance}. If in the old \term{class} there is any \term{slot} of the same name as a local \term{slot} in the \param{new-class}, the value of that \term{slot} is retained. This means that if the \term{slot} has a value, the value returned by \funref{slot-value} after \funref{change-class} is invoked is \funref{eql} to the value returned by \funref{slot-value} before \funref{change-class} is invoked. Similarly, if the \term{slot} was unbound, it remains unbound. The other \term{slots} are initialized as described in \secref\ChangingInstanceClass. After completing all other actions, \funref{change-class} invokes \funref{update-instance-for-different-class}. The generic function \funref{update-instance-for-different-class} can be used to assign values to slots in the transformed instance. \issue{CHANGE-CLASS-INITARGS:PERMIT} \Seesection\InitNewLocalSlots. \endissue{CHANGE-CLASS-INITARGS:PERMIT} \issue{CHANGE-CLASS-INITARGS:PERMIT} If the second of the above \term{methods} is selected, that \term{method} invokes \funref{change-class} on \param{instance}, \f{(find-class \param{new-class})}, and the \param{initargs}. \endissue{CHANGE-CLASS-INITARGS:PERMIT} \label Examples:: \code (defclass position () ()) (defclass x-y-position (position) ((x :initform 0 :initarg :x) (y :initform 0 :initarg :y))) (defclass rho-theta-position (position) ((rho :initform 0) (theta :initform 0))) (defmethod update-instance-for-different-class :before ((old x-y-position) (new rho-theta-position) &key) ;; Copy the position information from old to new to make new ;; be a rho-theta-position at the same position as old. (let ((x (slot-value old 'x)) (y (slot-value old 'y))) (setf (slot-value new 'rho) (sqrt (+ (* x x) (* y y))) (slot-value new 'theta) (atan y x)))) ;;; At this point an instance of the class x-y-position can be ;;; changed to be an instance of the class rho-theta-position using ;;; change-class: (setq p1 (make-instance 'x-y-position :x 2 :y 0)) (change-class p1 'rho-theta-position) ;;; The result is that the instance bound to p1 is now an instance of ;;; the class rho-theta-position. The update-instance-for-different-class ;;; method performed the initialization of the rho and theta slots based ;;; on the value of the x and y slots, which were maintained by ;;; the old instance. \endcode \label Examples:\None. \label Affected By:\None. \label Exceptional Situations:\None. \label See Also:: \funref{update-instance-for-different-class}, {\secref\ChangingInstanceClass} \label Notes:: The generic function \funref{change-class} has several semantic difficulties. First, it performs a destructive operation that can be invoked within a \term{method} on an \term{instance} that was used to select that \term{method}. When multiple \term{methods} are involved because \term{methods} are being combined, the \term{methods} currently executing or about to be executed may no longer be applicable. Second, some implementations might use compiler optimizations of slot \term{access}, and when the \term{class} of an \term{instance} is changed the assumptions the compiler made might be violated. This implies that a programmer must not use \funref{change-class} inside a \term{method} if any \term{methods} for that \term{generic function} \term{access} any \term{slots}, or the results are undefined. \endcom %%% ========== SLOT-BOUNDP \begincom{slot-boundp}\ftype{Function} %!!! Barmar: 88-002R says this is generic. I should check on this. -kmp 27-Aug-91 \label Syntax:: \DefunWithValues slot-boundp {instance slot-name} {generalized-boolean} \label Arguments and Values:: \param{instance}---an \term{object}. \param{slot-name}---a \term{symbol} naming a \term{slot} of \param{instance}. \param{generalized-boolean}---a \term{generalized boolean}. \label Description:: Returns \term{true} if the \term{slot} named \param{slot-name} in \param{instance} is bound; otherwise, returns \term{false}. \label Examples:\None. \label Affected By:\None. \label Exceptional Situations:: If no \term{slot} of the \term{name} \param{slot-name} exists in the \param{instance}, \funref{slot-missing} is called as follows: \code (slot-missing (class-of \i{instance}) \i{instance} \i{slot-name} 'slot-boundp) \endcode \issue{SLOT-MISSING-VALUES:SPECIFY} (If \funref{slot-missing} is invoked and returns a value, a \term{boolean equivalent} to its \term{primary value} is returned by \funref{slot-boundp}.) \endissue{SLOT-MISSING-VALUES:SPECIFY} \issue{SLOT-VALUE-METACLASSES:LESS-MINIMAL} The specific behavior depends on \param{instance}'s \term{metaclass}. An error is never signaled if \param{instance} has \term{metaclass} \typeref{standard-class}. An error is always signaled if \param{instance} has \term{metaclass} \typeref{built-in-class}. The consequences are undefined if \param{instance} has any other \term{metaclass}--an error might or might not be signaled in this situation. Note in particular that the behavior for \term{conditions} and \term{structures} is not specified. \endissue{SLOT-VALUE-METACLASSES:LESS-MINIMAL} \label See Also:: \funref{slot-makunbound}, \funref{slot-missing} \label Notes:: \Thefunction{slot-boundp} allows for writing \term{after methods} on \funref{initialize-instance} in order to initialize only those \term{slots} that have not already been bound. \MentionMetaObjects{slot-boundp}{slot-boundp-using-class} \endcom %%% ========== SLOT-EXISTS-P \begincom{slot-exists-p}\ftype{Function} %!!! Barmar: 88-002R says this is generic. I should check on this. -kmp 27-Aug-91 \label Syntax:: \DefunWithValues {slot-exists-p} {object slot-name} {generalized-boolean} \label Arguments and Values:: \issue{SLOT-VALUE-METACLASSES:LESS-MINIMAL} \param{object}---an \term{object}. \endissue{SLOT-VALUE-METACLASSES:LESS-MINIMAL} \param{slot-name}---a \term{symbol}. \param{generalized-boolean}---a \term{generalized boolean}. \label Description:: % \Thefunction{slot-exists-p} tests whether the \param{object} has % a \term{slot} of the given \term{name}. Returns \term{true} if the \param{object} has a \term{slot} named \param{slot-name}. \label Examples:\None. \label Affected By:: \macref{defclass}, \macref{defstruct} \label Exceptional Situations:\None. \label See Also:: \macref{defclass}, \funref{slot-missing} \label Notes:: \MentionMetaObjects{slot-exists-p}{slot-exists-p-using-class} \endcom %%% ========== SLOT-MAKUNBOUND \begincom{slot-makunbound}\ftype{Function} %!!! Barmar: 88-002R says this is generic. I should check on this. -kmp 27-Aug-91 \label Syntax:: \DefunWithValues {slot-makunbound} {instance slot-name} {instance} \label Arguments and Values:: \param{instance} -- instance. \param{Slot-name}---a \term{symbol}. \label Description:: \Thefunction{slot-makunbound} restores a \term{slot} of the name \param{slot-name} in an \param{instance} to the unbound state. \label Examples:\None. \label Affected By:\None. \label Exceptional Situations:: If no \term{slot} of the name \param{slot-name} exists in the \param{instance}, \funref{slot-missing} is called as follows: \code (slot-missing (class-of \i{instance}) \i{instance} \i{slot-name} 'slot-makunbound) \endcode \issue{SLOT-MISSING-VALUES:SPECIFY} (Any values returned by \funref{slot-missing} in this case are ignored by \funref{slot-makunbound}.) \endissue{SLOT-MISSING-VALUES:SPECIFY} \issue{SLOT-VALUE-METACLASSES:LESS-MINIMAL} The specific behavior depends on \param{instance}'s \term{metaclass}. An error is never signaled if \param{instance} has \term{metaclass} \typeref{standard-class}. An error is always signaled if \param{instance} has \term{metaclass} \typeref{built-in-class}. The consequences are undefined if \param{instance} has any other \term{metaclass}--an error might or might not be signaled in this situation. Note in particular that the behavior for \term{conditions} and \term{structures} is not specified. \endissue{SLOT-VALUE-METACLASSES:LESS-MINIMAL} \label See Also:: \funref{slot-boundp}, \funref{slot-missing} \label Notes:: \MentionMetaObjects{slot-makunbound}{slot-makunbound-using-class} \endcom %%% ========== SLOT-MISSING \begincom{slot-missing}\ftype{Standard Generic Function} \label Syntax:: \DefgenWithValues slot-missing {class object slot-name operation {\opt} new-value} {\starparam{result}} \label Method Signatures:: \Defmeth slot-missing {\vtop{\hbox{\specparam{class}{t} object slot-name} \hbox{operation {\opt} new-value}}} \label Arguments and Values:: \param{class}---the \term{class} of \param{object}. \param{object}---an \term{object}. \param{slot-name}---a \term{symbol} (the \term{name} of a would-be \term{slot}). \param{operation}---one of the \term{symbols} \funref{setf}, \funref{slot-boundp}, \funref{slot-makunbound}, or \funref{slot-value}. \param{new-value}---an \term{object}. \param{result}---an \term{object}. \label Description:: The generic function \funref{slot-missing} is invoked when an attempt is made to \term{access} a \term{slot} in an \param{object} whose \term{metaclass} is \typeref{standard-class} and the \term{slot} of the name \param{slot-name} is not a \term{name} of a \term{slot} in that \term{class}. The default \term{method} signals an error. The generic function \funref{slot-missing} is not intended to be called by programmers. Programmers may write \term{methods} for it. The generic function \funref{slot-missing} may be called during evaluation of \funref{slot-value}, \f{(setf slot-value)}, \funref{slot-boundp}, and \funref{slot-makunbound}. For each of these operations the corresponding \term{symbol} for the \param{operation} argument is \misc{slot-value}, \misc{setf}, \misc{slot-boundp}, and \misc{slot-makunbound} respectively. The optional \param{new-value} argument to \funref{slot-missing} is used when the operation is attempting to set the value of the \term{slot}. \issue{SLOT-MISSING-VALUES:SPECIFY} If \funref{slot-missing} returns, its values will be treated as follows: \beginlist \item{\bull} If the \param{operation} is \misc{setf} or \misc{slot-makunbound}, any \term{values} will be ignored by the caller. \item{\bull} If the \param{operation} is \misc{slot-value}, only the \term{primary value} will be used by the caller, and all other values will be ignored. \item{\bull} If the \param{operation} is \misc{slot-boundp}, any \term{boolean equivalent} of the \term{primary value} of the \term{method} might be is used, and all other values will be ignored. \endlist \endissue{SLOT-MISSING-VALUES:SPECIFY} \label Examples:\None. \label Affected By:\None. \label Exceptional Situations:: The default \term{method} on \funref{slot-missing} signals an error \oftype{error}. \label See Also:: \macref{defclass}, \funref{slot-exists-p}, \funref{slot-value} \label Notes:: The set of arguments (including the \term{class} of the instance) facilitates defining methods on the metaclass for \funref{slot-missing}. \endcom %%% ========== SLOT-UNBOUND \begincom{slot-unbound}\ftype{Standard Generic Function} \label Syntax:: \DefgenWithValues {slot-unbound} {class instance slot-name} {\starparam{result}} \label Method Signatures:: \Defmeth slot-unbound {\specparam{class}{t} instance slot-name} \label Arguments and Values:: \param{class}---the \term{class} of the \param{instance}. \param{instance}---the \param{instance} in which an attempt was made to \term{read} the \term{unbound} \term{slot}. \param{slot-name}---the \term{name} of the \term{unbound} \term{slot}. \param{result}---an \term{object}. \label Description:: The generic function \funref{slot-unbound} is called when an unbound \term{slot} is read in an \param{instance} whose metaclass is \typeref{standard-class}. The default \term{method} signals an error \issue{UNDEFINED-VARIABLES-AND-FUNCTIONS:COMPROMISE} \oftype{unbound-slot}. The name slot of the \typeref{unbound-slot} \term{condition} is initialized to the name of the offending variable, and the instance slot of the \typeref{unbound-slot} \term{condition} is initialized to the offending instance. \endissue{UNDEFINED-VARIABLES-AND-FUNCTIONS:COMPROMISE} The generic function \funref{slot-unbound} is not intended to be called by programmers. Programmers may write \term{methods} for it. \Thefunction{slot-unbound} is called only %%Looks like metaobjects to me. -kmp 15-Jan-91 %by \thefunction{slot-value-using-class} and thus indirectly by \funref{slot-value}. \issue{SLOT-MISSING-VALUES:SPECIFY} %% Per X3J13. -kmp 05-Oct-93 % If \funref{slot-unbound} returns, its values will be treated as follows: % % \beginlist % \item{\bull} % If the \param{operation} is \misc{setf} or \misc{slot-makunbound}, % any \term{values} will be ignored by the caller. % % \item{\bull} % If the \param{operation} is \misc{slot-value}, % only the \term{primary value} will be used by the caller, % and all other values will be ignored. % % \item{\bull} % If the \param{operation} is \misc{slot-boundp}, % any \term{boolean equivalent} of the \term{primary value} % of the \term{method} might be is used, % and all other values will be ignored. % \endlist If \funref{slot-unbound} returns, only the \term{primary value} will be used by the caller, and all other values will be ignored. \endissue{SLOT-MISSING-VALUES:SPECIFY} \label Examples:\None. \label Affected By:\None. \label Exceptional Situations:: \issue{UNDEFINED-VARIABLES-AND-FUNCTIONS:COMPROMISE} The default \term{method} on \funref{slot-unbound} signals an error \oftype{unbound-slot}. \endissue{UNDEFINED-VARIABLES-AND-FUNCTIONS:COMPROMISE} \label See Also:: \funref{slot-makunbound} \label Notes:: An unbound \term{slot} may occur if no \kwd{initform} form was specified for the \term{slot} and the \term{slot} value has not been set, or if \funref{slot-makunbound} has been called on the \term{slot}. \endcom %%% ========== SLOT-VALUE \begincom{slot-value}\ftype{Function} \label Syntax:: \DefunWithValues {slot-value} {object slot-name} {value} \label Arguments and Values:: \param{object}---an \term{object}. \param{name}---a \term{symbol}. \param{value}---an \term{object}. \label Description:: \Thefunction{slot-value} returns the \term{value} of the \term{slot} named \param{slot-name} in the \param{object}. If there is no \term{slot} named \param{slot-name}, \funref{slot-missing} is called. If the \term{slot} is unbound, \funref{slot-unbound} is called. %!!! Reflect this in the Syntax above? Or is (SETF SLOT-VALUE) described somewhere? The macro \macref{setf} can be used with \funref{slot-value} to change the value of a \term{slot}. \label Examples:: \code (defclass foo () ((a :accessor foo-a :initarg :a :initform 1) (b :accessor foo-b :initarg :b) (c :accessor foo-c :initform 3))) \EV # (setq foo1 (make-instance 'foo :a 'one :b 'two)) \EV # (slot-value foo1 'a) \EV ONE (slot-value foo1 'b) \EV TWO (slot-value foo1 'c) \EV 3 (setf (slot-value foo1 'a) 'uno) \EV UNO (slot-value foo1 'a) \EV UNO (defmethod foo-method ((x foo)) (slot-value x 'a)) \EV # (foo-method foo1) \EV UNO \endcode \label Affected By:\None. \label Exceptional Situations:: If an attempt is made to read a \term{slot} and no \term{slot} of the name \param{slot-name} exists in the \param{object}, \funref{slot-missing} is called as follows: \code (slot-missing (class-of \i{instance}) \i{instance} \i{slot-name} 'slot-value) \endcode \issue{SLOT-MISSING-VALUES:SPECIFY} (If \funref{slot-missing} is invoked, its \term{primary value} is returned by \funref{slot-value}.) \endissue{SLOT-MISSING-VALUES:SPECIFY} If an attempt is made to write a \term{slot} and no \term{slot} of the name \param{slot-name} exists in the \param{object}, \funref{slot-missing} is called as follows: \code (slot-missing (class-of \i{instance}) \i{instance} \i{slot-name} 'setf \i{new-value}) \endcode \issue{SLOT-MISSING-VALUES:SPECIFY} (If \funref{slot-missing} returns in this case, any \term{values} are ignored.) \endissue{SLOT-MISSING-VALUES:SPECIFY} \issue{SLOT-VALUE-METACLASSES:LESS-MINIMAL} The specific behavior depends on \param{object}'s \term{metaclass}. An error is never signaled if \param{object} has \term{metaclass} \typeref{standard-class}. An error is always signaled if \param{object} has \term{metaclass} \typeref{built-in-class}. The consequences are %% Per X3J13. -kmp 05-Oct-93 %undefined unspecified if \param{object} has any other \term{metaclass}--an error might or might not be signaled in this situation. Note in particular that the behavior for \term{conditions} and \term{structures} is not specified. \endissue{SLOT-VALUE-METACLASSES:LESS-MINIMAL} \label See Also:: \funref{slot-missing}, \funref{slot-unbound}, \macref{with-slots} \label Notes:: \MentionMetaObjects{slot-value}{slot-value-using-class} Implementations may optimize \funref{slot-value} by compiling it inline. \endcom %%% ========== METHOD-QUALIFIERS \begincom{method-qualifiers}\ftype{Standard Generic Function} \label Syntax:: \DefgenWithValues method-qualifiers {method} {qualifiers} \label Method Signatures:: \Defmeth method-qualifiers {\specparam{method}{standard-method}} \label Arguments and Values:: \param{method}---a \term{method}. \param{qualifiers}---a \term{proper list}. \label Description:: Returns a \term{list} of the \term{qualifiers} of the \param{method}. \label Examples:: \code (defmethod some-gf :before ((a integer)) a) \EV # (method-qualifiers *) \EV (:BEFORE) \endcode \label Affected By:\None. \label Exceptional Situations:\None. \label See Also:: \macref{define-method-combination} \label Notes:\None. \endcom %%% ========== NO-APPLICABLE-METHOD \begincom{no-applicable-method}\ftype{Standard Generic Function} \label Syntax:: \DefgenWithValues no-applicable-method {generic-function {\rest} function-arguments} {\starparam{result}} \label Method Signatures:: \Defmeth no-applicable-method {\vtop{\hbox{\specparam{generic-function}{t}} \hbox{{\rest} function-arguments}}} \label Arguments and Values:: %!!! But the signature above says T, not STANDARD-GENERIC-FUNCTION ...? -kmp 9-May-91 \param{generic-function}---a \term{generic function} %% Per X3J13. -kmp 05-Oct-93 % of the class \typeref{standard-generic-function} on which no \term{applicable method} was found. \param{function-arguments}---\term{arguments} to the \param{generic-function}. \param{result}---an \term{object}. \label Description:: The generic function \funref{no-applicable-method} is called when a \term{generic function} %% Per X3J13. -kmp 05-Oct-93 %of \theclass{standard-generic-function} is invoked and no \term{method} on that \term{generic function} is applicable. % "default \term{method}" => "\term{default method}" per X3J13. -kmp 05-Oct-93 The \term{default method} signals an error. The generic function \funref{no-applicable-method} is not intended to be called by programmers. Programmers may write \term{methods} for it. \label Examples:\None. \label Affected By:\None. \label Exceptional Situations:: The default \term{method} signals an error \oftype{error}. \label See Also:: \label Notes:\None. \endcom %%% ========== NO-NEXT-METHOD \begincom{no-next-method}\ftype{Standard Generic Function} \label Syntax:: \DefgenWithValues no-next-method {generic-function method {\rest} args} {\starparam{result}} \label Method Signatures:: \Defmeth no-next-method {\vtop{\hbox{\specparam{generic-function}{standard-generic-function}} \hbox{\specparam{method}{standard-method}} \hbox{{\rest} args}}} \label Arguments and Values:: \param{generic-function} -- \term{generic function} to which \param{method} belongs. \param{method} -- \term{method} that contained the call to \funref{call-next-method} for which there is no next \term{method}. \param{args} -- arguments to \funref{call-next-method}. \param{result}---an \term{object}. \label Description:: \TheGF{no-next-method} is called by \funref{call-next-method} when there is no \term{next method}. \TheGF{no-next-method} is not intended to be called by programmers. Programmers may write \term{methods} for it. \label Examples:\None. \label Affected By:\None. \label Exceptional Situations:: The system-supplied \term{method} on \funref{no-next-method} signals an error \oftype{error}. \editornote{KMP: perhaps control-error??} \label See Also:: \funref{call-next-method} \label Notes:\None. \endcom %%% ========== REMOVE-METHOD \begincom{remove-method}\ftype{Standard Generic Function} \label Syntax:: \DefgenWithValues remove-method {generic-function method} {generic-function} \label Method Signatures:: \Defmeth remove-method {\vtop{\hbox{\specparam{generic-function}{standard-generic-function}} \hbox{method}}} \label Arguments and Values:: \param{generic-function}---a \term{generic function}. \param{method}---a \term{method}. \label Description:: \TheGF{remove-method} removes a \term{method} from \param{generic-function} by modifying the \param{generic-function} (if necessary). \funref{remove-method} must not signal an error if the \term{method} is not one of the \term{methods} on the \param{generic-function}. \label Examples:\None. \label Affected By:\None. \label Exceptional Situations:\None. \label See Also:: \funref{find-method} \label Notes:\None. \endcom \issue{GENERIC-FLET-POORLY-DESIGNED:DELETE} % %%% ========== GENERIC-FLET % %%% ========== GENERIC-LABELS % % \begincom{generic-flet, generic-labels}\ftype{Special Operator} % % \label Syntax:: % % \DefspecWithValuesNewline generic-flet % {\vtop{\hbox{\paren{\starparen{function-name % lambda-list % \interleave{\down{option} | % \stardown{method-description}}}}} % \hbox{\starparam{form}}}} % {\starparam{result}} % % \DefspecWithValuesNewline generic-labels % {\vtop{\hbox{\paren{\starparen{function-name % lambda-list % \interleave{\down{option} | % \stardown{method-description}}}}} % \hbox{\starparam{form}}}} % {\starparam{result}} % % {\GFauxOptionsAndMethDesc} % % \label Arguments and Values:: % % \editornote{KMP: Treatment of documentation?}%!!! % % \param{function-name}, \param{lambda-list}, \param{option}, \param{method-qualifier}, % \param{specialized-lambda-list}---the same as for \macref{defgeneric}. % % \param{method-definition}---the same as for \macref{defmethod}. % % \param{forms}---an \term{implicit progn}. % % \param{results}---the \term{values} returned by the \param{forms}. % % \label Description:: % % \Thespecop{generic-flet} is analogous to \thespecop{flet}, and % \thespecop{generic-labels} is analogous to \thespecop{labels}. % % The \term{forms} are \term{evaluated} in a \term{lexical environment} % in which \term{function} \term{bindings} for the \param{function-names} have % been \term{established}. % The \term{value} of each \term{binding} is a \term{fresh} \term{generic function}, % with \term{methods} as specified by the corresponding \param{method-description}. % The \term{bindings} of the \term{function-names} have \term{lexical scope}, % and the \term{generic functions} (and their \term{methods}) have \term{indefinite extent}. % % For \specref{generic-flet}, % the \term{scope} of the \term{bindings} for the \param{function-names} % includes only the \param{forms}, % not the bodies of the local definitions of the \term{methods}. % Within the method bodies, references to any of the \param{function-names} % refer to global \term{functions} with coincidentally similar names, % not to the \term{generic functions} established for use by the \param{forms}. % It is thus not possible to define recursive \term{functions} % with \specref{generic-flet}. % % For \specref{generic-labels}, % the \term{scope} of the \term{bindings} for the \param{function-names} % includes the entire \specref{generic-labels} \term{form}, % including not only the \param{forms}, % but also the bodies of the local definitions of the \term{methods}. % It is thus possible to define recursive \term{functions} % with \specref{generic-labels}. % % The body of each \term{method} is enclosed in an \term{implicit block}. % If \param{function-name} is a \term{symbol}, % the \term{implicit block} has that \term{name}. % If \param{function-name} is a \term{list} of the form \f{(setf \param{sym})}, % the \term{name} of the \term{implicit block} is \param{sym}. % % \label Examples:\None. % % \label Affected By:\None. % % \label Exceptional Situations:\None. % % \label See Also:: % % \specref{flet}, % \specref{labels}, % \macref{defmethod}, % \macref{defgeneric}, % \macref{generic-function} % % \label Notes:\None. % % \endcom % % % %%% ========== GENERIC-FUNCTION % \begincom{generic-function}\ftype{Macro} % % \label Syntax:: % % \DefmacWithValues generic-function % {lambda-list \interleave{\down{option} | \starparam{method-description}}} % {generic-function} % % {\GFauxOptionsAndMethDesc} % % \label Arguments and Values:: % % \editornote{KMP: Treatment of documentation?}%!!! % % \param{Option}, \param{method-qualifier}, % and \param{specialized-lambda-list} are the same as for % \macref{defgeneric}. % % \param{generic-function}---a \term{generic function} \term{object}. % % \label Description:: % % Creates an \term{anonymous} \term{generic function} with the % set of \term{methods} specified by its \param{method-descriptions}. % % %%I don't think this is really needed. -kmp 15-Jan-91 % % If no \param{method-descriptions} are supplied, % % an \term{anonymous} \term{generic function} with no \term{methods} is created. % % \label Examples:\None. % % \label Affected By:\None. % % \label Exceptional Situations:\None. % % \label See Also:: % % \macref{defgeneric}, % \specref{generic-flet}, % \specref{generic-labels}, % \macref{defmethod} % % \label Notes:\None. % % \endcom \endissue{GENERIC-FLET-POORLY-DESIGNED:DELETE} %%% ========== MAKE-INSTANCE \begincom{make-instance}\ftype{Standard Generic Function} \label Syntax:: \issue{INITIALIZATION-FUNCTION-KEYWORD-CHECKING} \DefgenWithValues make-instance {class {\rest} initargs {\key} {\allowotherkeys}} {instance} \endissue{INITIALIZATION-FUNCTION-KEYWORD-CHECKING} \label Method Signatures:: \Defmeth make-instance {\specparam{class}{standard-class} {\rest} initargs} \Defmeth make-instance {\specparam{class}{symbol} {\rest} initargs} \label Arguments and Values:: %!!! I'd rather this were called class-name. -kmp 15-Jan-91 %!!! Or maybe class designator? -kmp 18-Feb-91 \param{class}---a \term{class}, or a \term{symbol} that names a \term{class}. \param{initargs}---an \term{initialization argument list}. \param{instance}---a \term{fresh} \term{instance} of \term{class} \param{class}. \label Description:: The \term{generic function} \funref{make-instance} creates and returns a new \term{instance} of the given \param{class}. If the second of the above \term{methods} is selected, that \term{method} invokes \funref{make-instance} on the arguments \f{(find-class \param{class})} and \param{initargs}. The initialization arguments are checked within \funref{make-instance}. The \term{generic function} \funref{make-instance} may be used as described in \secref\ObjectCreationAndInit. \label Affected By:\None. \label Exceptional Situations:: If any of the initialization arguments has not been declared as valid, an error \oftype{error} is signaled. \label See Also:: \macref{defclass}, \funref{class-of}, \funref{allocate-instance}, \funref{initialize-instance}, {\secref\ObjectCreationAndInit} %% Per X3J13. -kmp 05-Oct-93 \label Notes:\None. %The meta-object protocol can be used to define new methods on %\funref{make-instance} to replace the object-creation protocol. \endcom %%% ========== MAKE-INSTANCES-OBSOLETE \begincom{make-instances-obsolete}\ftype{Standard Generic Function} \label Syntax:: \DefgenWithValues make-instances-obsolete {class} {class} \label Method Signatures:: \Defmeth make-instances-obsolete {\specparam{class}{standard-class}} \Defmeth make-instances-obsolete {\specparam{class}{symbol}} \label Arguments and Values:: \param{class}---a \term{class designator}. \label Description:: \Thefunction{make-instances-obsolete} has the effect of initiating the process of updating the instances of the \term{class}. During updating, the generic function \funref{update-instance-for-redefined-class} will be invoked. The generic function \funref{make-instances-obsolete} is invoked automatically by the system when \macref{defclass} has been used to redefine an existing standard class and the set of local \term{slots} \term{accessible} in an instance is changed or the order of \term{slots} in storage is changed. It can also be explicitly invoked by the user. If the second of the above \term{methods} is selected, that \term{method} invokes \funref{make-instances-obsolete} on \f{(find-class \param{class})}. \label Examples:: \label Affected By:\None. \label Exceptional Situations:\None. \label See Also:: \funref{update-instance-for-redefined-class}, {\secref\ClassReDef} \label Notes:\None. \endcom %%% ========== MAKE-LOAD-FORM \begincom{make-load-form}\ftype{Standard Generic Function} \issue{MAKE-LOAD-FORM-CONFUSION:REWRITE} \issue{LOAD-OBJECTS:MAKE-LOAD-FORM} \label Syntax:: \DefgenWithValues {make-load-form} {object {\opt} environment} {creation-form\brac{, initialization-form}} \label Method Signatures:: \Defmeth make-load-form {\specparam{object}{standard-object} {\opt} environment} \Defmeth make-load-form {\specparam{object}{structure-object} {\opt} environment} \Defmeth make-load-form {\specparam{object}{condition} {\opt} environment} \Defmeth make-load-form {\specparam{object}{class} {\opt} environment} \label Arguments and Values:: \param{object}---an \term{object}. % Barrett: Moved up from end, so arguments first, then values. \param{environment}---an \term{environment object}. \param{creation-form}---a \term{form}. \param{initialization-form}---a \term{form}. \label Description:: \TheGF{make-load-form} creates and returns one or two \term{forms}, a \param{creation-form} and an \param{initialization-form}, that enable \funref{load} to construct an \term{object} equivalent to \param{object}. %% Added per item 1 of MAKE-LOAD-FORM-CONFUSION: \param{Environment} is an \term{environment object} corresponding to the \term{lexical environment} in which the \term{forms} will be processed. % %% Added with rewrites per item 1.1 of MAKE-LOAD-FORM-CONFUSION. % %% I had to do some minor fooling with the wording to make it read % %% better using `modern' terminology. -kmp 11-Feb-92 % \funref{make-load-form} is called by the \term{file compiler} when % \param{object} is referenced as a \term{literal object} % in a \term{file} being compiled % %by \funref{compile-file} % if the \term{object} is a \term{generalized instance} % of \typeref{standard-object}, \typeref{structure-object}, % \typeref{condition}, or any of a (possibly empty) \term{implementation-dependent} % %list % set of other \term{classes}. % The \term{file compiler} will only call \funref{make-load-form} once for the \term{same} % \term{object} within a single \term{file}. % Barrett: Commented out the above, instead referencing the appropriate % section describing how the compiler performs constant processing. The \term{file compiler} calls \funref{make-load-form} to process certain \term{classes} of \term{literal objects}; \seesection\CallingMakeLoadForm. %% Added per item 1.2 of MAKE-LOAD-FORM-CONFUSION: \term{Conforming programs} may call \funref{make-load-form} directly, providing \param{object} is a \term{generalized instance} of % Barrett: Fix dangling reference, now that list has been moved. % one of the % explicitly named \term{classes} mentioned previously. \typeref{standard-object}, \typeref{structure-object}, or \typeref{condition}. The creation form is a \term{form} that, when evaluated at \funref{load} time, should return an \term{object} that is equivalent to \param{object}. The exact meaning of equivalent depends on the \term{type} of \term{object} and is up to the programmer who defines a \term{method} for \funref{make-load-form}; \seesection\LiteralsInCompiledFiles. %This is the same type of equivalence discussed % in issue CONSTANT-COMPILABLE-TYPES. The initialization form is a \term{form} that, when evaluated at \funref{load} time, should perform further initialization of the \term{object}. The value returned by the initialization form is ignored. % Barrett: Flush "method" -- its the value returned by the function that's % being talked about. %If the \funref{make-load-form} method If \funref{make-load-form} returns only one value, the initialization form is \nil, which has no effect. If \param{object} appears as a constant in the initialization form, at \funref{load} time it will be replaced by the equivalent \term{object} constructed by the creation form; this is how the further initialization gains access to the \term{object}. % Both the creation and initialization forms can contain references to \term{objects} % of user-defined \term{types} (defined precisely below). %% Rewritten per item 1.4 of MAKE-LOAD-FORM-CONFUSION: Both the \param{creation-form} and the \param{initialization-form} may contain references to any \term{externalizable object}. However, there must not be any circular dependencies in creation forms. An example of a circular dependency is when the creation form for the object \f{X} contains a reference to the object \f{Y}, and the creation form for the object \f{Y} contains a reference to the object \f{X}. %A simpler % example would be when the creation form for the object X contains % a reference to X itself. Initialization forms are not subject to any restriction against circular dependencies, which is the reason that initialization forms exist; see the example of circular data structures below. % The creation form for an \term{object} is always evaluated before the % initialization form for that \term{object}. % When either the creation form or % the initialization form references other \term{objects} % of user-defined \term{types} % that have not been referenced earlier in the % \funref{compile-file}, the % compiler collects all of the creation and initialization forms. Each % initialization form is evaluated as soon as possible after its % creation form, as determined by data flow. If the initialization form % for an \term{object} does not reference any other % \term{objects} of user-defined % \term{types} % that have not been referenced earlier in the \funref{compile-file}, the % initialization form is evaluated immediately after the creation form. % If a creation or initialization form \f{F} references other % \term{objects} of % user-defined \term{types} that have not been referenced earlier in the % \funref{compile-file}, % the creation forms for those other \term{objects} are evaluated % before \f{F}, and the initialization forms for those other % \term{objects} are % also evaluated before \f{F} whenever they do not depend on the % \term{object} % created or initialized by % \f{F}. Where the above rules do not uniquely % determine an order of evaluation, which of the possible orders of % evaluation is chosen is \term{implementation-dependent}. % \idxtext{order of evaluation}\idxtext{evaluation order} %% Rewritten per item 1.5 of MAKE-LOAD-FORM-CONFUSION: The creation form for an \term{object} is always \term{evaluated} before the initialization form for that \term{object}. When either the creation form or the initialization form references other \term{objects} that have not been referenced earlier in the \term{file} being \term{compiled}, the \term{compiler} ensures that all of the referenced \term{objects} have been created before \term{evaluating} the referencing \term{form}. When the referenced \term{object} is of a \term{type} which %\funref{compile-file} the \term{file compiler} processes using \funref{make-load-form}, this involves \term{evaluating} the creation form returned for it. (This is the reason for the prohibition against circular references among creation forms). Each initialization form is \term{evaluated} as soon as possible after its associated creation form, as determined by data flow. If the initialization form for an \term{object} does not reference any other \term{objects} not referenced earlier in the \term{file} and processed by %\funref{compile-file} the \term{file compiler} using \funref{make-load-form}, the initialization form is evaluated immediately after the creation form. If a creation or initialization form $F$ does contain references to such \term{objects}, the creation forms for those other objects are evaluated before $F$, and the initialization forms for those other \term{objects} are also evaluated before $F$ whenever they do not depend on the \term{object} created or initialized by $F$. Where these rules do not uniquely determine an order of \term{evaluation} between two creation/initialization forms, the order of \term{evaluation} is unspecified. While these creation and initialization forms are being evaluated, the \term{objects} are possibly in an uninitialized state, analogous to the state of an \term{object} between the time it has been created by \funref{allocate-instance} and it has been processed fully by \funref{initialize-instance}. Programmers writing \term{methods} for \funref{make-load-form} must take care in manipulating \term{objects} not to depend on \term{slots} that have not yet been initialized. It is \term{implementation-dependent} whether \funref{load} calls \funref{eval} on the \term{forms} or does some other operation that has an equivalent effect. For example, the \term{forms} might be translated into different but equivalent \term{forms} and then evaluated, they might be compiled and the resulting functions called by \funref{load}, or they might be interpreted by a special-purpose function different from \funref{eval}. All that is required is that the effect be equivalent to evaluating the \term{forms}. % Barrett: Add method descriptions, per make-load-form-confusion. The \term{method} \term{specialized} on \typeref{class} returns a creation \term{form} using the \term{name} of the \term{class} if the \term{class} has a \term{proper name} in \param{environment}, signaling an error \oftype{error} if it does not have a \term{proper name}. \term{Evaluation} of the creation \term{form} uses the \term{name} to find the \term{class} with that \term{name}, as if by \term{calling} \funref{find-class}. If a \term{class} with that \term{name} has not been defined, then a \term{class} may be computed in an \term{implementation-defined} manner. If a \term{class} cannot be returned as the result of \term{evaluating} the creation \term{form}, then an error \oftype{error} is signaled. %!!! Barrett: MAKE-LOAD-FORM-CONFUSION sayed "... may define additional % \term{conforming methods} ...", but we never actually came up % with a definition for that term. That whole issue is not % currently addressed by the standard, so I'm not going to try % to fix it just here. Both \term{conforming implementations} and \term{conforming programs} may further \term{specialize} \funref{make-load-form}. \label Examples:: \code (defclass obj () ((x :initarg :x :reader obj-x) (y :initarg :y :reader obj-y) (dist :accessor obj-dist))) \EV # (defmethod shared-initialize :after ((self obj) slot-names &rest keys) (declare (ignore slot-names keys)) (unless (slot-boundp self 'dist) (setf (obj-dist self) (sqrt (+ (expt (obj-x self) 2) (expt (obj-y self) 2)))))) \EV # (defmethod make-load-form ((self obj) &optional environment) (declare (ignore environment)) ;; Note that this definition only works because X and Y do not ;; contain information which refers back to the object itself. ;; For a more general solution to this problem, see revised example below. `(make-instance ',(class-of self) :x ',(obj-x self) :y ',(obj-y self))) \EV # (setq obj1 (make-instance 'obj :x 3.0 :y 4.0)) \EV # (obj-dist obj1) \EV 5.0 (make-load-form obj1) \EV (MAKE-INSTANCE 'OBJ :X '3.0 :Y '4.0) \endcode In the above example, an equivalent \term{instance} of \f{obj} is reconstructed by using the values of two of its \term{slots}. The value of the third \term{slot} is derived from those two values. \medbreak Another way to write the \funref{make-load-form} \term{method} in that example is to use \funref{make-load-form-saving-slots}. The code it generates might yield a slightly different result from the \funref{make-load-form} \term{method} shown above, but the operational effect will be the same. For example: \smallbreak \code ;; Redefine method defined above. (defmethod make-load-form ((self obj) &optional environment) (make-load-form-saving-slots self :slot-names '(x y) :environment environment)) \EV # ;; Try MAKE-LOAD-FORM on object created above. (make-load-form obj1) \EV (ALLOCATE-INSTANCE '#), (PROGN (SETF (SLOT-VALUE '# 'X) '3.0) (SETF (SLOT-VALUE '# 'Y) '4.0) (INITIALIZE-INSTANCE '#)) \endcode \medbreak In the following example, \term{instances} of \f{my-frob} are ``interned'' in some way. An equivalent \term{instance} is reconstructed by using the value of the name slot as a key for searching existing \term{objects}. In this case the programmer has chosen to create a new \term{object} if no existing \term{object} is found; alternatively an error could have been signaled in that case. \smallbreak \code (defclass my-frob () ((name :initarg :name :reader my-name))) (defmethod make-load-form ((self my-frob) &optional environment) (declare (ignore environment)) `(find-my-frob ',(my-name self) :if-does-not-exist :create)) \endcode \medbreak In the following example, the data structure to be dumped is circular, because each parent has a list of its children and each child has a reference back to its parent. If \funref{make-load-form} is called on one \term{object} in such a structure, the creation form creates an equivalent \term{object} and fills in the children slot, which forces creation of equivalent \term{objects} for all of its children, grandchildren, etc. At this point none of the parent \term{slots} have been filled in. The initialization form fills in the parent \term{slot}, which forces creation of an equivalent \term{object} for the parent if it was not already created. Thus the entire tree is recreated at \funref{load} time. At compile time, \funref{make-load-form} is called once for each \term{object} in the tree. All of the creation forms are evaluated, in \term{implementation-dependent} order, and then all of the initialization forms are evaluated, also in \term{implementation-dependent} order. \smallbreak \code (defclass tree-with-parent () ((parent :accessor tree-parent) (children :initarg :children))) (defmethod make-load-form ((x tree-with-parent) &optional environment) (declare (ignore environment)) (values ;; creation form `(make-instance ',(class-of x) :children ',(slot-value x 'children)) ;; initialization form `(setf (tree-parent ',x) ',(slot-value x 'parent)))) \endcode \medbreak In the following example, the data structure to be dumped has no special properties and an equivalent structure can be reconstructed simply by reconstructing the \term{slots}' contents. \smallbreak \code (defstruct my-struct a b c) (defmethod make-load-form ((s my-struct) &optional environment) (make-load-form-saving-slots s :environment environment)) \endcode \label Affected By:\None. \label Exceptional Situations:: % \funref{make-load-form} of an \term{object} % of \term{metaclass} \typeref{standard-class} or \typeref{structure-class} % for which no user-defined \term{method} is applicable % signals an error \oftype{error}. % It is valid to implement this either by defining default % methods on \typeref{standard-object} and \typeref{structure-object} % that signal an error \oftype{error} % or by having no \term{applicable method} for those \term{classes}. %% Rewritten per item 1.3 of MAKE-LOAD-FORM-CONFUSION: The \term{methods} \term{specialized} on \typeref{standard-object}, \typeref{structure-object}, and \typeref{condition} all signal an error \oftype{error}. % Barrett: Add per make-load-form-confusion. It is \term{implementation-dependent} whether \term{calling} \funref{make-load-form} on a \term{generalized instance} of a \term{system class} signals an error or returns creation and initialization \term{forms}. \label See Also:: \funref{compile-file}, \funref{make-load-form-saving-slots}, {\secref\CallingMakeLoadForm} {\secref\Evaluation}, {\secref\Compilation} \label Notes:: The \term{file compiler} %\funref{compile-file} calls \funref{make-load-form} in specific circumstances detailed in \secref\CallingMakeLoadForm. %% Removed per item 1.2 of MAKE-LOAD-FORM-CONFUSION: % It is valid for user programs to % call \funref{make-load-form} in other circumstances, providing \param{object}'s % \term{metaclass} is neither \typeref{built-in-class} % nor a \term{subclass} of \typeref{built-in-class}. % Barrett: Add per make-load-form-confusion. Some \term{implementations} may provide facilities for defining new \term{subclasses} of \term{classes} which are specified as \term{system classes}. (Some likely candidates include \typeref{generic-function}, \typeref{method}, and \typeref{stream}). Such \term{implementations} should document how the \term{file compiler} processes \term{instances} of such \term{classes} when encountered as \term{literal objects}, and should document any relevant \term{methods} for \funref{make-load-form}. \endissue{LOAD-OBJECTS:MAKE-LOAD-FORM} \endissue{MAKE-LOAD-FORM-CONFUSION:REWRITE} \endcom %%% ========== MAKE-LOAD-FORM-SAVING-SLOTS \begincom{make-load-form-saving-slots}\ftype{Function} \issue{MAKE-LOAD-FORM-CONFUSION:REWRITE} % Barrett: Issue reference for LOAD-OBJECTS was missing. \issue{LOAD-OBJECTS:MAKE-LOAD-FORM} \label Syntax:: \DefunWithValuesNewline make-load-form-saving-slots {object {\key} slot-names environment} {creation-form, initialization-form} \label Arguments and Values:: \param{object}---an \term{object}. \param{slot-names}---a \term{list}. \param{environment}---an \term{environment object}. \param{creation-form}---a \term{form}. \param{initialization-form}---a \term{form}. \label Description:: \issue{MAKE-LOAD-FORM-SAVING-SLOTS:NO-INITFORMS} % Returns \term{forms} that, when \term{evaluated}, will construct an % \term{object} equivalent to \param{object} using \funref{make-instance} % and \macref{setf} of \funref{slot-value} for \term{slots} with values, % or \funref{slot-makunbound} for \term{slots} without values, % or using other \term{functions} of equivalent effect. % \funref{make-load-form-saving-slots} works for any \term{object} % of \term{metaclass} \typeref{standard-class} or \typeref{structure-class}. Returns \term{forms} that, when \term{evaluated}, will construct an \term{object} equivalent to \param{object}, without \term{executing} \term{initialization forms}. The \term{slots} in the new \term{object} that correspond to initialized \term{slots} in \param{object} are initialized using the values from \param{object}. Uninitialized \term{slots} in \param{object} are not initialized in the new \term{object}. \funref{make-load-form-saving-slots} works for any \term{instance} of \typeref{standard-object} or \typeref{structure-object}. \endissue{MAKE-LOAD-FORM-SAVING-SLOTS:NO-INITFORMS} %Barmar: What does it return if object is a structure? % MAKE-INSTANCE can't be used on structure classes, can it? %KMP: I think that's what "functions of equivalent effect" is supposed to answer. \param{Slot-names} is a \term{list} of the names of the \term{slots} to preserve. If \param{slot-names} is not supplied, its value is all of the \term{local slots}. \funref{make-load-form-saving-slots} returns two values, thus it can deal with circular structures. Whether the result is useful in an application depends on whether the \param{object}'s \term{type} and slot contents fully capture the application's idea of the \param{object}'s state. \param{Environment} is the environment in which the forms will be processed. \label Examples:\None. \label Side Effects:\None. \label Affected By:\None. \label Exceptional Situations:\None. \label See Also:: \funref{make-load-form}, \funref{make-instance}, \macref{setf}, \funref{slot-value}, \funref{slot-makunbound} \label Notes:: \funref{make-load-form-saving-slots} can be useful in user-written \funref{make-load-form} methods. % Barrett: Remember to put in end marker. \endissue{LOAD-OBJECTS:MAKE-LOAD-FORM} \endissue{MAKE-LOAD-FORM-CONFUSION:REWRITE} \issue{MAKE-LOAD-FORM-SAVING-SLOTS:NO-INITFORMS} When the \term{object} is an \term{instance} of \typeref{standard-object}, \funref{make-load-form-saving-slots} could return a creation form that \term{calls} \funref{allocate-instance} and an initialization form that contains \term{calls} to \macref{setf} of \funref{slot-value} and \funref{slot-makunbound}, though other \term{functions} of similar effect might actually be used. \endissue{MAKE-LOAD-FORM-SAVING-SLOTS:NO-INITFORMS} \endcom %%% ========== WITH-ACCESSORS \begincom{with-accessors}\ftype{Macro} \issue{DECLS-AND-DOC} \label Syntax:: \DefmacWithValuesNewline with-accessors {{\paren{\starparam{slot-entry}}} instance-form \starparam{declaration} \starparam{form}} {\starparam{result}} \auxbnf{slot-entry}{\paren{variable-name accessor-name}} \label Arguments and Values:: \param{variable-name}---a \term{variable name}; \noeval. \param{accessor-name}---a \term{function name}; \noeval. \param{instance-form}---a \term{form}; \eval. \param{declaration}---a \misc{declare} \term{expression}; \noeval. \param{forms}---an \term{implicit progn}. \param{results}---the \term{values} returned by the \param{forms}. \label Description:: Creates a lexical environment in which the slots specified by \param{slot-entry} are lexically available through their accessors as if they were variables. The macro \macref{with-accessors} invokes the appropriate accessors to \param{access} the \term{slots} specified by \param{slot-entry}. Both \macref{setf} and \specref{setq} can be used to set the value of the \term{slot}. \label Examples:: \code (defclass thing () ((x :initarg :x :accessor thing-x) (y :initarg :y :accessor thing-y))) \EV # (defmethod (setf thing-x) :before (new-x (thing thing)) (format t "~&Changing X from ~D to ~D in ~S.~%" (thing-x thing) new-x thing)) (setq thing1 (make-instance 'thing :x 1 :y 2)) \EV # (setq thing2 (make-instance 'thing :x 7 :y 8)) \EV # (with-accessors ((x1 thing-x) (y1 thing-y)) thing1 (with-accessors ((x2 thing-x) (y2 thing-y)) thing2 (list (list x1 (thing-x thing1) y1 (thing-y thing1) x2 (thing-x thing2) y2 (thing-y thing2)) (setq x1 (+ y1 x2)) (list x1 (thing-x thing1) y1 (thing-y thing1) x2 (thing-x thing2) y2 (thing-y thing2)) (setf (thing-x thing2) (list x1)) (list x1 (thing-x thing1) y1 (thing-y thing1) x2 (thing-x thing2) y2 (thing-y thing2))))) \OUT Changing X from 1 to 9 in #. \OUT Changing X from 7 to (9) in #. \EV ((1 1 2 2 7 7 8 8) 9 (9 9 2 2 7 7 8 8) (9) (9 9 2 2 (9) (9) 8 8)) \endcode \label Affected By:: \macref{defclass} \label Exceptional Situations:: The consequences are undefined if any \param{accessor-name} is not the name of an accessor for the \param{instance}. \label See Also:: \macref{with-slots}, \specref{symbol-macrolet} \label Notes:: A \macref{with-accessors} expression of the form: $$\openup1\jot\vbox{\settabs\+\cr \+{\tt (with-accessors} (${\hbox{\i{slot-entry}}}\sub 1% \ldots{\hbox{\i{slot-entry}}}\sub n$) \i{instance-form} ${\hbox{\i{form}}}\sub 1% \ldots{\hbox{\i{form}}}\sub k$)\cr}$$ \noindent expands into the equivalent of $$\openup1\jot\vbox{\settabs\+\cr \+{\tt (}&{\tt let ((}$in$ \i{instance-form}{\tt ))}\cr \+&{\tt (symbol-macrolet (}${\hbox{\i{Q}}}\sub 1\ldots% {\hbox{\i{Q}}}\sub n${\tt )} ${\hbox{\i{form}}}\sub 1% \ldots{\hbox{\i{form}}}\sub k${\tt ))}\cr}$$ \noindent where ${\hbox{\i{Q}}}\sub i$ is $${\vbox{\hbox{{\tt (}${\hbox{\i{variable-name}}}\sub i$ () % {\tt (${\hbox{\i{accessor-name}}}\sub{i}\ in$))}}}}$$ \endissue{DECLS-AND-DOC} \endcom %%% ========== WITH-SLOTS \begincom{with-slots}\ftype{Macro} \issue{DECLS-AND-DOC} \label Syntax:: \DefmacWithValuesNewline with-slots {\paren{\starparam{slot-entry}} instance-form \starparam{declaration} \starparam{form}} {\starparam{result}} \auxbnf{slot-entry}{slot-name | \paren{variable-name slot-name}} \label Arguments and Values:: \param{slot-name}---a \term{slot} \term{name}; \noeval. \param{variable-name}---a \term{variable name}; \noeval. \param{instance-form}---a \term{form}; evaluted to produce \param{instance}. \param{instance}---an \term{object}. \param{declaration}---a \misc{declare} \term{expression}; \noeval. \param{forms}---an \term{implicit progn}. \param{results}---the \term{values} returned by the \param{forms}. \label Description:: The macro \macref{with-slots} \term{establishes} a %lexical context \term{lexical environment} for referring to the \term{slots} in the \param{instance} named by the given \param{slot-names} as though they were \term{variables}. Within such a context the value of the \term{slot} can be specified by using its slot name, as if it were a lexically bound variable. Both \macref{setf} and \specref{setq} can be used to set the value of the \term{slot}. The macro \macref{with-slots} translates an appearance of the slot name as a \term{variable} into a call to \funref{slot-value}. \label Examples:: \code (defclass thing () ((x :initarg :x :accessor thing-x) (y :initarg :y :accessor thing-y))) \EV # (defmethod (setf thing-x) :before (new-x (thing thing)) (format t "~&Changing X from ~D to ~D in ~S.~%" (thing-x thing) new-x thing)) (setq thing (make-instance 'thing :x 0 :y 1)) \EV # (with-slots (x y) thing (incf x) (incf y)) \EV 2 (values (thing-x thing) (thing-y thing)) \EV 1, 2 (setq thing1 (make-instance 'thing :x 1 :y 2)) \EV # (setq thing2 (make-instance 'thing :x 7 :y 8)) \EV # (with-slots ((x1 x) (y1 y)) thing1 (with-slots ((x2 x) (y2 y)) thing2 (list (list x1 (thing-x thing1) y1 (thing-y thing1) x2 (thing-x thing2) y2 (thing-y thing2)) (setq x1 (+ y1 x2)) (list x1 (thing-x thing1) y1 (thing-y thing1) x2 (thing-x thing2) y2 (thing-y thing2)) (setf (thing-x thing2) (list x1)) (list x1 (thing-x thing1) y1 (thing-y thing1) x2 (thing-x thing2) y2 (thing-y thing2))))) \OUT Changing X from 7 to (9) in #. \EV ((1 1 2 2 7 7 8 8) 9 (9 9 2 2 7 7 8 8) (9) (9 9 2 2 (9) (9) 8 8)) \endcode \label Affected By:: \macref{defclass} \label Exceptional Situations:: The consequences are undefined if any \param{slot-name} is not the name of a \term{slot} in the \param{instance}. \label See Also:: \macref{with-accessors}, \funref{slot-value}, \specref{symbol-macrolet} \label Notes:: A \macref{with-slots} expression of the form: $$\openup1\jot\vbox{\settabs\+\cr \+{\tt (with-slots} (${\hbox{\i{slot-entry}}}\sub 1% \ldots{\hbox{\i{slot-entry}}}\sub n$) \i{instance-form} ${\hbox{\i{form}}}\sub 1% \ldots{\hbox{\i{form}}}\sub k$)\cr}$$ \noindent expands into the equivalent of $$\openup1\jot\vbox{\settabs\+\cr \+{\tt (}&{\tt let ((}$in$ \i{instance-form}{\tt ))}\cr \+&{\tt (symbol-macrolet (}${\hbox{\i{Q}}}\sub 1\ldots% {\hbox{\i{Q}}}\sub n${\tt )} ${\hbox{\i{form}}}\sub 1% \ldots{\hbox{\i{form}}}\sub k${\tt ))}\cr}$$ \noindent where ${\hbox{\i{Q}}}\sub i$ is $$\vbox{\hbox{{\tt (}${\hbox{\i{slot-entry}}}\sub i$ () % {\tt (slot-value }$in$ '${\hbox{\i{slot-entry}}}\sub i${\tt ))}}}$$ \noindent if ${\hbox{\i{slot-entry}}}\sub i$ is a \term{symbol} and is $${\vbox{\hbox{{\tt (}${\hbox{\i{variable-name}}}\sub i$ () % {\tt (slot-value }$in$ '${\hbox{\i{slot-name}}}\sub i${\tt ))}}}}$$ \noindent if ${\hbox{\i{slot-entry}}}\sub i$ is of the form $$\vbox{\hbox{{\tt (}${\hbox{\i{variable-name}}}\sub i$ % ${\hbox{\i{slot-name}}}\sub i${\tt )}}}$$ \endissue{DECLS-AND-DOC} \endcom %%% ========== DEFCLASS \begincom{defclass}\ftype{Macro} \label Syntax:: %%Syntax fixed per X3J13. -kmp 05-Oct-93 \DefmacWithValuesNewline defclass {\param{class-name} \paren{\star{\curly{\param{superclass-name}}}} \paren{\star{\curly{\i{slot-specifier}}}} $\lbrack\!\lbrack\downarrow\!\hbox{\i{class-option}}\,\rbrack\!\rbrack$} {new-class} \settabs\+\hskip\leftskip&\cr \+&\cleartabs\i{slot-specifier}::$=$ &\i{slot-name} $\vert$ (\i{slot-name} $\lbrack\!\lbrack\downarrow\!\hbox{\i{slot-option}}\,\rbrack\!\rbrack$)\cr \Vskip 1pc! \+&\i{slot-name}::$=$ \term{symbol}\cr \Vskip 1pc! \+&\cleartabs\i{slot-option}::$=$ &\star{\curly{\kwd{reader} \param{reader-function-name}}} $\vert$ \cr \+&&\star{\curly{\kwd{writer} \param{writer-function-name}}} $\vert$ \cr \+&&\star{\curly{\kwd{accessor} \param{reader-function-name}}} $\vert$ \cr \+&&\curly{\kwd{allocation} \param{allocation-type}} $\vert$ \cr \+&&\star{\curly{\kwd{initarg} \param{initarg-name}}} $\vert$ \cr \+&&\curly{\kwd{initform} \param{form}} $\vert$ \cr \+&&\curly{\kwd{type} \param{type-specifier}} $\vert$ \cr \+&&\curly{\kwd{documentation} \term{string}} \cr \Vskip 1pc! \+&\i{function-name}::$=$ \curly{\term{symbol} $\vert$ {\tt (setf \term{symbol})}}\cr \Vskip 1pc! \+&\cleartabs\param{class-option}::$=$ &(\kwd{default-initargs} \f{.} \param{initarg-list}) $\vert$ \cr \+&&(\kwd{documentation} \term{string}) $\vert$ \cr \+&&(\kwd{metaclass} \param{class-name}) \cr \Vskip 1pc! \label Arguments and Values:: %!!! Treatment of documentation? \param{Class-name}---a \term{non-nil} \term{symbol}. \param{Superclass-name}--a \term{non-nil} \term{symbol}. \param{Slot-name}--a \term{symbol}. The \param{slot-name} argument is %!!! Isn't there a more concise way to say this? a \term{symbol} that is syntactically valid for use as a variable name. \param{Reader-function-name}---a \term{non-nil} \term{symbol}. \kwd{reader} can be supplied more than once for a given \term{slot}. \param{Writer-function-name}---a \term{generic function} name. \kwd{writer} can be supplied more than once for a given \term{slot}. \param{Reader-function-name}---a \term{non-nil} \term{symbol}. \kwd{accessor} can be supplied more than once for a given \term{slot}. \param{Allocation-type}---(member \kwd{instance} \kwd{class}). \kwd{allocation} can be supplied once at most for a given \term{slot}. \param{Initarg-name}---a \term{symbol}. \kwd{initarg} can be supplied more than once for a given \term{slot}. \param{Form}---a \term{form}. \kwd{init-form} can be supplied once at most for a given \term{slot}. \param{Type-specifier}---a \term{type specifier}. \kwd{type} can be supplied once at most for a given \term{slot}. \param{Class-option}--- refers to the \term{class} as a whole or to all class \term{slots}. \param{Initarg-list}---a \term{list} of alternating initialization argument \term{names} and default initial value \term{forms}. \kwd{default-initargs} can be supplied at most once. \param{Class-name}---a \term{non-nil} \term{symbol}. \kwd{metaclass} can be supplied once at most. %The \i{class-name} argument is a \term{non-nil} symbol. %Each \i{superclass-name} argument is a \term{non-nil} symbol. %Each \i{slot-specifier} argument is the name of the slot or a list %consisting of the slot name followed by zero or more slot options. %The \i{reader-function-name} argument is a \term{non-nil} symbol. %The \i{writer-function-name} argument is a function specifier. %The \i{initarg-name} argument is a symbol. %!!! Ugh. Surely this should not be so. -kmp 24-Apr-91 \param{new-class}---the new \term{class} \term{object}. \label Description:: The macro \macref{defclass} defines a new named \term{class}. It returns the new \term{class} \term{object} as its result. The syntax of \macref{defclass} provides options for specifying initialization arguments for \term{slots}, for specifying default initialization values for \term{slots}, and for requesting that \term{methods} on specified \term{generic functions} be automatically generated for reading and writing the values of \term{slots}. No reader or writer functions are defined by default; their generation must be explicitly requested. However, \term{slots} can always be \term{accessed} using \funref{slot-value}. Defining a new \term{class} also causes a \term{type} of the same name to be defined. The predicate \f{(typep \param{object} \param{class-name})} returns true if the \term{class} of the given \param{object} is the \term{class} named by \param{class-name} itself or a subclass of the class \param{class-name}. A \term{class} \term{object} can be used as a \term{type specifier}. Thus \f{(typep \param{object} \param{class})} returns \term{true} if the \term{class} of the \param{object} is \param{class} itself or a subclass of \param{class}. The \param{class-name} argument specifies the \term{proper name} of the new \term{class}. %If a \term{class} %with the same proper name already exists and that %\term{class} is an \term{instance} of \typeref{standard-class}, and if the %\macref{defclass} form for the definition of the new \term{class} %specifies a \term{class} of class \typeref{standard-class}, the %definition of the existing \term{class} is replaced. If a \term{class} with the same \term{proper name} already exists and that \term{class} is an \term{instance} of \typeref{standard-class}, and if the \macref{defclass} form for the definition of the new \term{class} specifies a \term{class} of \term{class} \typeref{standard-class}, the existing \term{class} is redefined, and instances of it (and its \term{subclasses}) are updated to the new definition at the time that they are next \term{accessed}. For details, \seesection\ClassReDef. % addressed in the packages chapter. --sjl 5 Mar 92 %\issue{LISP-SYMBOL-REDEFINITION:MAR89-X3J13} %The consequences are undefined if a \term{symbol} in \thepackage{common-lisp} %is used as the \param{class-name} argument. %\endissue{LISP-SYMBOL-REDEFINITION:MAR89-X3J13} Each \param{superclass-name} argument specifies a direct \term{superclass} of the new \term{class}. %% gray addition If the \term{superclass} list is empty, then the \term{superclass} defaults depending on the \term{metaclass}, with \typeref{standard-object} being the default for \typeref{standard-class}. The new \term{class} will inherit \term{slots} and \term{methods} from each of its direct \term{superclasses}, from their direct \term{superclasses}, and so on. For a discussion of how \term{slots} and \term{methods} are inherited, \seesection\Inheritance. %Each \i{slot-specifier} argument is the \term{name} of the slot or a list %consisting of the slot name followed by zero or more slot options. %The \i{slot-name} argument is a symbol that is syntactically valid %for use as a Common Lisp variable name. If there are any duplicate %slot names, an error is signaled. The following slot options are available: \beginlist \itemitem{\bull} The \kwd{reader} slot option specifies that an \term{unqualified method} is to be defined on the \term{generic function} named \param{reader-function-name} to read the value of the given \term{slot}. \itemitem{\bull} The \kwd{writer} slot option specifies that an \term{unqualified method} is to be defined on the \term{generic function} named \param{writer-function-name} to write the value of the \term{slot}. \itemitem{\bull} The \kwd{accessor} slot option specifies that an \term{unqualified method} is to be defined on the generic function named \param{reader-function-name} to read the value of the given \term{slot} and that an \term{unqualified method} is to be defined on the \term{generic function} named \f{(setf \param{reader-function-name})} to be used with \macref{setf} to modify the value of the \term{slot}. \itemitem{\bull} The \kwd{allocation} slot option is used to specify where storage is to be allocated for the given \term{slot}. Storage for a \term{slot} can be located in each instance or in the \term{class} \term{object} itself. The value of the \param{allocation-type} argument can be either the keyword \kwd{instance} or the keyword \kwd{class}. If the \kwd{allocation} slot option is not specified, the effect is the same as specifying \f{:allocation :instance}. \beginlist \itemitem{--} If \param{allocation-type} is \kwd{instance}, a \term{local slot} of the name \param{slot-name} is allocated in each instance of the \term{class}. \itemitem{--} If \param{allocation-type} is \kwd{class}, a shared \term{slot} of the given name is allocated in the \term{class} \term{object} created by this \macref{defclass} form. The value of the \term{slot} is shared by all \term{instances} of the \term{class}. If a class $C\sub1$ defines such a \term{shared slot}, any subclass $C\sub2$ of $C\sub1$ will share this single \term{slot} unless the \macref{defclass} form for $C\sub2$ specifies a \term{slot} of the same \term{name} or there is a superclass of $C\sub2$ that precedes $C\sub1$ in the class precedence list of $C\sub2$ and that defines a \term{slot} of the same \term{name}. \endlist \itemitem{\bull} The \kwd{initform} slot option is used to provide a default initial value form to be used in the initialization of the \term{slot}. This \term{form} is evaluated every time it is used to initialize the \term{slot}. The lexical environment in which this \term{form} is evaluated is the lexical environment in which the \macref{defclass} form was evaluated. Note that the lexical environment refers both to variables and to functions. For \term{local slots}, the dynamic environment is the dynamic environment in which \funref{make-instance} is called; for shared \term{slots}, the dynamic environment is the dynamic environment in which the \macref{defclass} form was evaluated. \Seesection\ObjectCreationAndInit. No implementation is permitted to extend the syntax of \macref{defclass} to allow \f{(\param{slot-name} \param{form})} as an abbreviation for \f{(\param{slot-name} :initform \param{form})}. \reviewer{Barmar: Can you extend this to mean something else?} \itemitem{\bull} The \kwd{initarg} slot option declares an initialization argument named \param{initarg-name} and specifies that this initialization argument initializes the given \term{slot}. If the initialization argument has a value in the call to \funref{initialize-instance}, the value will be stored into the given \term{slot}, and the slot's \kwd{initform} slot option, if any, is not evaluated. If none of the initialization arguments specified for a given \term{slot} has a value, the \term{slot} is initialized according to the \kwd{initform} slot option, if specified. \itemitem{\bull} The \kwd{type} slot option specifies that the contents of the \term{slot} will always be of the specified data type. It effectively declares the result type of the reader generic function when applied to an \term{object} of this \term{class}. The consequences of attempting to store in a \term{slot} a value that does not satisfy the type of the \term{slot} are undefined. The \kwd{type} slot option is further discussed in \secref\SlotInheritance. \itemitem{\bull} The \kwd{documentation} slot option provides a \term{documentation string} for the \term{slot}. \kwd{documentation} can be supplied once at most for a given \term{slot}. \reviewer{Barmar: How is this retrieved?} \endlist Each class option is an option that refers to the \term{class} as a whole. %!!! Barmar alleges that there are none of these: %or to all class \term{slots}. The following class options are available: \beginlist \itemitem{\bull} The \kwd{default-initargs} class option is followed by a list of alternating initialization argument \term{names} and default initial value forms. If any of these initialization arguments does not appear in the initialization argument list supplied to \funref{make-instance}, the corresponding default initial value form is evaluated, and the initialization argument \term{name} and the \term{form}'s value are added to the end of the initialization argument list before the instance is created; \seesection\ObjectCreationAndInit. The default initial value form is evaluated each time it is used. The lexical environment in which this \term{form} is evaluated is the lexical environment in which the \macref{defclass} form was evaluated. The dynamic environment is the dynamic environment in which \funref{make-instance} was called. If an initialization argument \term{name} appears more than once in a \kwd{default-initargs} class option, an error is signaled. \itemitem{\bull} \issue{DOCUMENTATION-FUNCTION-BUGS:FIX} The \kwd{documentation} class option causes a \term{documentation string} to be attached with the \term{class} \term{object}, and attached with kind \misc{type} to the \param{class-name}. \kwd{documentation} can be supplied once at most. \endissue{DOCUMENTATION-FUNCTION-BUGS:FIX} \itemitem{\bull} The \kwd{metaclass} class option is used to specify that instances of the \term{class} being defined are to have a different metaclass than the default provided by the system (\theclass{standard-class}). \endlist Note the following rules of \macref{defclass} for \term{standard classes}: \beginlist \itemitem{\bull} It is not required that the \term{superclasses} of a \term{class} be defined before the \macref{defclass} form for that \term{class} is evaluated. \itemitem{\bull} All the \term{superclasses} of a \term{class} must be defined before an \term{instance} of the \term{class} can be made. \itemitem{\bull} A \term{class} must be defined before it can be used as a parameter specializer in a \macref{defmethod} form. \endlist The \OS\ can be extended to cover situations where these rules are not obeyed. Some slot options are inherited by a \term{class} from its \term{superclasses}, and some can be shadowed or altered by providing a local slot description. No class options except \kwd{default-initargs} are inherited. For a detailed description of how \term{slots} and slot options are inherited, \seesection\SlotInheritance. The options to \macref{defclass} can be extended. It is required that all implementations signal an error if they observe a class option or a slot option that is not implemented locally. It is valid to specify more than one reader, writer, accessor, or initialization argument for a \term{slot}. No other slot option can appear more than once in a single slot description, or an error is signaled. If no reader, writer, or accessor is specified for a \term{slot}, the \term{slot} can only be \term{accessed} by \thefunction{slot-value}. %The macro \macref{defclass} defines a new named \term{class}. %Defining a new \term{class} also causes a %\term{type} of the same \term{name} to be defined. %The \kwd{reader} slot option causes an \term{unqualified method} %to be defined on the \term{generic function} named %\param{reader-function-name} to read the value of the given \term{slot}. %The \kwd{writer} slot option causes an \term{unqualified method} %to be defined on the \term{generic function} named %\param{writer-function-name} to write the value of the \term{slot}. %The \kwd{accessor} slot option causes an \term{unqualified method} %to be defined on the \term{generic function} named %\param{reader-function-name} to read the value of the given \term{slot} %and an \term{unqualified method} to be defined on the %\term{generic function} named {\tt (setf \param{reader-function-name})} to be %used with \macref{setf} to modify the value of the \term{slot}. %The \kwd{initarg} slot option declares an initialization argument %named \param{initarg-name}. \issue{COMPILE-FILE-HANDLING-OF-TOP-LEVEL-FORMS:CLARIFY} % added qualification about top-level-ness --sjl 5 Mar 92 If a \macref{defclass} \term{form} appears as a \term{top level form}, the \term{compiler} must make the \term{class} \term{name} be recognized as a valid \term{type} \term{name} in subsequent declarations (as for \macref{deftype}) and be recognized as a valid \term{class} \term{name} for \macref{defmethod} \term{parameter specializers} and for use as the \kwd{metaclass} option of a subsequent \macref{defclass}. The \term{compiler} must make %%!!! this doesn't look right. maybe "a class object"? -kmp 7-Jun-91 the \term{class} definition available to be returned by \funref{find-class} when its \param{environment} \term{argument} is a value received as the \term{environment parameter} of a \term{macro}. \endissue{COMPILE-FILE-HANDLING-OF-TOP-LEVEL-FORMS:CLARIFY} \label Examples:\None. \label Affected By:\None. \label Exceptional Situations:: If there are any duplicate slot names, an error \oftype{program-error} is signaled. If an initialization argument \term{name} appears more than once in \kwd{default-initargs} class option, an error \oftype{program-error} is signaled. If any of the following slot options appears more than once in a single slot description, an error \oftype{program-error} is signaled: \kwd{allocation}, \kwd{initform}, \kwd{type}, \kwd{documentation}. It is required that all implementations signal an error \oftype{program-error} if they observe a class option or a slot option that is not implemented locally. %%gray's annotation %>Other possible errors are an undefined metaclass or attempting to %>redefine the name of an existing type with an incompatible metaclass %>{e.g. DEFCLASS for a name previously defined by DEFSTRUCT or DEFTYPE}. \label See Also:: \funref{documentation}, \funref{initialize-instance}, \funref{make-instance}, \funref{slot-value}, {\secref\Classes}, {\secref\Inheritance}, {\secref\ClassReDef}, {\secref\DeterminingtheCPL}, {\secref\ObjectCreationAndInit} \label Notes:\None. \endcom %%% ========== DEFGENERIC \begincom{defgeneric}\ftype{Macro} \issue{DECLS-AND-DOC} \label Syntax:: \DefmacWithValuesNewline defgeneric {function-name gf-lambda-list \interleave{\down{option} | \stardown{method-description}}} {new-generic} \auxbnf{option}{\paren{\kwd{argument-precedence-order} \plusparam{parameter-name}} |\CR \paren{\misc{declare} \plusparam{gf-declaration}} |\CR \paren{\kwd{documentation} \param{gf-documentation}} |\CR \paren{\kwd{method-combination} \param{method-combination} \starparam{method-combination-argument}} |\CR \paren{\kwd{generic-function-class} \param{generic-function-class}} |\CR \paren{\kwd{method-class} \param{method-class}}} \auxbnf{method-description}{\lparen\kwd{method} \vtop{\hbox{\starparam{method-qualifier} \param{specialized-lambda-list}} \hbox{{\DeclsAndDoc} \starparam{form}\rparen}}} \label Arguments and Values:: \param{function-name}---a \term{function name}. \param{generic-function-class}---a \term{non-nil} \term{symbol} naming a \term{class}. \param{gf-declaration}---an \declref{optimize} \term{declaration specifier}; other \term{declaration specifiers} are not permitted. %% Barmar: What's the theory here? %% Are \declref{ignore} and \declref{dynamic-extent} in or out?} % \declref{special}, \declref{ftype}, \declref{function}, % \declref{inline}, \declref{notinline}, and \declref{declaration} % declarations are not permitted. \param{gf-documentation}---a \term{string}; \noeval. \param{gf-lambda-list}---a \term{generic function lambda list}. \param{method-class}---a \term{non-nil} \term{symbol} naming a \term{class}. \param{method-combination-argument}---an \term{object.} %% Barmar: Redundant with info to follow. %suitable as \term{arguments} to the \param{method-combination-name}; %the standard method combination type does not support %any \term{arguments}. %All types of method combination defined by the %short form of \macref{define-method-combination} accept %\kwd{order}, which defaults to \kwd{most-specific-first}. \param{method-combination-name}---a \term{symbol} naming a \term{method combination} \term{type}. \param{method-qualifiers}, \param{specialized-lambda-list}, \param{declarations}, \param{documentation}, \param{forms}---as per \macref{defmethod}. \param{new-generic}---the \term{generic function} \term{object}. \param{parameter-name}---a \term{symbol} that names a \term{required parameter} in the \param{lambda-list}. (If the \kwd{argument-precedence-order} option is specified, each \term{required parameter} in the \param{lambda-list} must be used exactly once as a \param{parameter-name}.) \label Description:: The macro \macref{defgeneric} is used to define a \term{generic function} or to specify options and declarations that pertain to a \term{generic function} as a whole. %!!! Rewrite in terms of "fboundp" to avoid function calls? If \param{function-name} is a \term{list} it must be of the form {\tt (setf \i{symbol})}. If \f{(fboundp \param{function-name})} is \term{false}, a new \term{generic function} is created. \issue{FUNCTION-NAME:LARGE} If \f{(fdefinition \param{function-name})} is a \term{generic function}, that \endissue{FUNCTION-NAME:LARGE} \term{generic function} is modified. If \param{function-name} names an \term{ordinary function}, a \term{macro}, or a \term{special operator}, an error is signaled. The effect of the \macref{defgeneric} macro is as if the following three steps were performed: first, \term{methods} defined by previous \macref{defgeneric} \term{forms} are removed; \reviewer{Barmar: Shouldn't this (second) be first?} second, \funref{ensure-generic-function} is called; and finally, \term{methods} specified by the current \macref{defgeneric} \term{form} are added to the \term{generic function}. Each \param{method-description} defines a \term{method} on the \term{generic function}. The \term{lambda list} of each \term{method} must be congruent with the \term{lambda list} specified by the \param{gf-lambda-list} option. If no \term{method} descriptions are specified and a \term{generic function} of the same name does not already exist, a \term{generic function} with no \term{methods} is created. The \param{gf-lambda-list} argument of \macref{defgeneric} specifies the shape of \term{lambda lists} for the \term{methods} on this \term{generic function}. All \term{methods} on the resulting \term{generic function} must have \term{lambda lists} that are congruent with this shape. If a \macref{defgeneric} form is evaluated and some \term{methods} for that \term{generic function} have \term{lambda lists} that are not congruent with that given in the \macref{defgeneric} form, an error is signaled. For further details on method congruence, \seesection\GFMethodLambdaListCongruency. The \term{generic function} passes to the \term{method} all the argument values passed to it, and only those; default values are not supported. Note that optional and keyword arguments in method definitions, however, can have default initial value forms and can use supplied-p parameters. The following options are provided. \issue{DEFGENERIC-DECLARE:ALLOW-MULTIPLE} Except as otherwise noted, \endissue{DEFGENERIC-DECLARE:ALLOW-MULTIPLE} a given option may occur only once. \beginlist \itemitem{\bull} The \kwd{argument-precedence-order} option is used to specify the order in which the required arguments in a call to the \term{generic function} are tested for specificity when selecting a particular \term{method}. Each required argument, as specified in the \param{gf-lambda-list} argument, must be included exactly once as a \param{parameter-name} so that the full and unambiguous precedence order is supplied. If this condition is not met, an error is signaled. \reviewer{Barmar: What is the default order?} \itemitem{\bull} The \misc{declare} option is used to specify declarations that pertain to the \term{generic function}. An \declref{optimize} \term{declaration specifier} is allowed. It specifies whether method selection should be optimized for speed or space, but it has no effect on \term{methods}. To control how a \term{method} is optimized, an \declref{optimize} declaration must be placed directly in the \macref{defmethod} \term{form} or method description. The optimization qualities \misc{speed} and \misc{space} are the only qualities this standard requires, but an implementation can extend the \CLOS\ to recognize other qualities. A simple implementation that has only one method selection technique and ignores \declref{optimize} \term{declaration specifiers} is valid. The \declref{special}, \declref{ftype}, \declref{function}, \declref{inline}, \declref{notinline}, and \declref{declaration} declarations are not permitted. Individual implementations can extend the \misc{declare} option to support additional declarations. \editornote{KMP: Does ``additional'' mean including special, ftype, etc.? Or only other things that are not mentioned here?} If an implementation notices a \term{declaration specifier} that it does not support and that has not been proclaimed as a non-standard \term{declaration identifier} name in a \declref{declaration} \term{proclamation}, it should issue a warning. \editornote{KMP: The wording of this previous sentence, particularly the word ``and'' suggests to me that you can `proclaim declaration' of an unsupported declaration (e.g., ftype) in order to suppress the warning. That seems wrong. Perhaps it instead means to say ``does not support or is both undefined and not proclaimed declaration.''} \issue{DEFGENERIC-DECLARE:ALLOW-MULTIPLE} The \misc{declare} option may be specified more than once. The effect is the same as if the lists of \term{declaration specifiers} had been appended together into a single list and specified as a single \misc{declare} option. \endissue{DEFGENERIC-DECLARE:ALLOW-MULTIPLE} \itemitem{\bull} The \kwd{documentation} argument is a \term{documentation string} to be attached to the \term{generic function} \term{object}, and to be attached with kind \misc{function} to the \param{function-name}. \itemitem{\bull} The \kwd{generic-function-class} option may be used to specify that the \term{generic function} is to have a different \term{class} than the default provided by the system (\theclass{standard-generic-function}). The \param{class-name} argument is the name of a \term{class} that can be the \term{class} of a \term{generic function}. If \param{function-name} specifies an existing \term{generic function} that has a different value for the \kwd{generic-function-class} argument and the new generic function \term{class} is compatible with the old, \funref{change-class} is called to change the \term{class} of the \term{generic function}; otherwise an error is signaled. \itemitem{\bull} The \kwd{method-class} option is used to specify that all \term{methods} on this \term{generic function} are to have a different \term{class} from the default provided by the system (\theclass{standard-method}). The \param{class-name} argument is the name of a \term{class} that is capable of being the \term{class} of a \term{method}. \reviewer{Barmar: Is \funref{change-class} called on existing methods?} \itemitem{\bull} The \kwd{method-combination} option is followed by a symbol that names a type of method combination. The arguments (if any) that follow that symbol depend on the type of method combination. Note that the standard method combination type does not support any arguments. However, all types of method combination defined by the short form of \macref{define-method-combination} accept an optional argument named \param{order}, defaulting to \kwd{most-specific-first}, where a value of \kwd{most-specific-last} reverses the order of the primary \term{methods} without affecting the order of the auxiliary \term{methods}. \endlist The \param{method-description} arguments define \term{methods} that will be associated with the \term{generic function}. The \param{method-qualifier} and \param{specialized-lambda-list} arguments in a method description are the same as for \macref{defmethod}. The \param{form} arguments specify the method body. The body of the \term{method} is enclosed in an \term{implicit block}. If \param{function-name} is a \term{symbol}, this block bears the same name as the \term{generic function}. If \param{function-name} is a \term{list} of the form {\tt (setf \param{symbol})}, the name of the block is \param{symbol}. Implementations can extend \macref{defgeneric} to include other options. It is required that an implementation signal an error if it observes an option that is not implemented locally. \issue{COMPILE-FILE-HANDLING-OF-TOP-LEVEL-FORMS:CLARIFY} \macref{defgeneric} is not required to perform any compile-time side effects. In particular, the \term{methods} are not installed for invocation during compilation. An \term{implementation} may choose to store information about the \term{generic function} for the purposes of compile-time error-checking (such as checking the number of arguments on calls, or noting that a definition for the function name has been seen). \endissue{COMPILE-FILE-HANDLING-OF-TOP-LEVEL-FORMS:CLARIFY} \label Examples:: \label Affected By:\None. \label Exceptional Situations:: If \param{function-name} names an \term{ordinary function}, a \term{macro}, or a \term{special operator}, an error \oftype{program-error} is signaled. Each required argument, as specified in the \param{gf-lambda-list} argument, must be included exactly once as a \param{parameter-name}, or an error \oftype{program-error} is signaled. The \term{lambda list} of each \term{method} specified by a \param{method-description} must be congruent with the \term{lambda list} specified by the \param{gf-lambda-list} option, or an error \oftype{error} is signaled. If a \macref{defgeneric} form is evaluated and some \term{methods} for that \term{generic function} have \term{lambda lists} that are not congruent with that given in the \macref{defgeneric} form, an error \oftype{error} is signaled. A given \param{option} may occur only once, or an error \oftype{program-error} is signaled. \reviewer{Barmar: This says that an error is signaled if you specify the same generic function class as it already has!} If \param{function-name} specifies an existing \term{generic function} that has a different value for the \kwd{generic-function-class} argument and the new generic function \term{class} is compatible with the old, \funref{change-class} is called to change the \term{class} of the \term{generic function}; otherwise an error \oftype{error} is signaled. Implementations can extend \macref{defgeneric} to include other options. It is required that an implementation signal an error \oftype{program-error} if it observes an option that is not implemented locally. \label See Also:: \macref{defmethod}, \funref{documentation}, \funref{ensure-generic-function}, \issue{GENERIC-FUNCTION-POORLY-DESIGNED:DELETE} %\macref{generic-function}, \typeref{generic-function}, \endissue{GENERIC-FUNCTION-POORLY-DESIGNED:DELETE} {\secref\GFMethodLambdaListCongruency} \label Notes:\None. \endissue{DECLS-AND-DOC} \endcom %%% ========== DEFMETHOD \begincom{defmethod}\ftype{Macro} \issue{DECLS-AND-DOC} \label Syntax:: %!!! Barmar: \macref{defun} and \macref{defmacro} don't bother to show this detail % for the specialized lambda list, so why does \macref{defmethod}? \DefmacWithValuesNewline {defmethod} {\vtop{\hbox{\i{function-name} \star{\curly{\i{method-qualifier}}} \i{specialized-lambda-list}} \hbox{{\DeclsAndDoc} \starparam{form}}}} {new-method} \Vskip1pc!\null \i{function-name}::$=$ \curly{\term{symbol} $\vert$ {\tt (setf \term{symbol})}} \Vskip1pc!\null \i{method-qualifier}::$=$ \term{non-list} \Vskip1pc!\null \settabs\+\hskip\leftskip&\cr \+&\i{specialized-lambda-list}::$=$ (&\star{\curly{\param{var} $\vert$ {\rm (}{\param{var} \i{parameter-specializer-name}}{\rm )}}} \cr \+&&\ttbrac{{\opt} \star{\curly{\param{var} $\vert$ {\rm (}var \ttbrac{\param{initform} {\brac{\param{supplied-p-parameter}}} }{\rm )}}}} \cr \+&&\ttbrac{{\tt\&rest} \param{var}} \cr \+&&{\tt \lbracket}{\key{}}&\star{\curly{\param{var} $\vert$ {\rm (}\curly{\param{var} $\vert$ {\rm (}\term{keyword}\param{var}{\rm )}} \ttbrac{\param{initform} \brac{\param{supplied-p-parameter}} }{\rm )}}}\cr \+&&&\brac{\keyref{allow-other-keys}} {\tt \rbracket} \cr \+&&\ttbrac{{\tt\&aux} \star{\curly{\param{var} $\vert$ {\rm (}\param{var} \brac{\param{initform}} {\rm )}}}} {\rm )} \cr \Vskip1pc!\null \+&\i{parameter-specializer-name}::$=$ \term{symbol} $\vert$ {\rm (}{\tt eql} \param{eql-specializer-form}{\rm )}\cr \Vskip 1pc! \label Arguments and Values:: \param{declaration}---a \misc{declare} \term{expression}; \noeval. \param{documentation}---a \term{string}; \noeval. \param{var}---a \term{variable} \term{name}. \param{eql-specializer-form}---a \term{form}. \param{Form}---a \term{form}. \param{Initform}---a \term{form}. \param{Supplied-p-parameter}---variable name. \param{new-method}---the new \term{method} \term{object}. \label Description:: The macro \macref{defmethod} defines a \term{method} on a \term{generic function}. %!!! Rewrite to use "fbound" ? If {\tt (fboundp \i{function-name})} is \nil, a \term{generic function} is created with default values for the argument precedence order (each argument is more specific than the arguments to its right in the argument list), for the generic function class (\theclass{standard-generic-function}), for the method class (\theclass{standard-method}), and for the method combination type (the standard method combination type). The \term{lambda list} of the \term{generic function} is congruent with the \term{lambda list} of the \term{method} being defined; if the \macref{defmethod} form mentions keyword arguments, the \term{lambda list} of the \term{generic function} will mention {\tt &key} (but no keyword arguments). If \i{function-name} names an \term{ordinary function}, a \term{macro}, or a \term{special operator}, an error is signaled. If a \term{generic function} is currently named by {\it function-name}, the \term{lambda list} of the \term{method} must be congruent with the \term{lambda list} of the \term{generic function}. If this condition does not hold, an error is signaled. For a definition of congruence in this context, \seesection\GFMethodLambdaListCongruency. %% gray says redundant with syntax spec. %If \i{function-name} is a \term{list}, %it must be of the form {\tt (setf \i{symbol})}. %\i{Function-name} names the \term{generic function} %on which the \term{method} is defined. Each \i{method-qualifier} argument is an \term{object} that is used by method combination to identify the given \term{method}. The method combination type might further restrict what a method \term{qualifier} can be. The standard method combination type allows for \term{unqualified methods} and \term{methods} whose sole \term{qualifier} is one of the keywords \kwd{before}, \kwd{after}, or \kwd{around}. The \i{specialized-lambda-list} argument is like an ordinary \term{lambda list} except that the \term{names} of required parameters can be replaced by specialized parameters. A specialized parameter is a list of the form \f{(\param{var} \i{parameter-specializer-name})}. Only required parameters can be specialized. If \i{parameter-specializer-name} is a \term{symbol} it names a \term{class}; if it is a \term{list}, it is of the form \f{(eql \param{eql-specializer-form})}. The parameter specializer name \f{(eql \param{eql-specializer-form})} indicates that the corresponding argument must be \funref{eql} to the \term{object} that is the value of \param{eql-specializer-form} for the \term{method} to be applicable. %%gray/moon addition The \param{eql-specializer-form} is evaluated at the time that the expansion of the \macref{defmethod} macro is evaluated. %% If no \term{parameter specializer name} is specified for a given required parameter, the \term{parameter specializer} defaults to \theclass{t}. For further discussion, \seesection\IntroToMethods. The \param{form} arguments specify the method body. The body of the \term{method} is enclosed in an \term{implicit block}. If \i{function-name} is a \term{symbol}, this block bears the same \term{name} as the \term{generic function}. If \i{function-name} is a \term{list} of the form {\tt (setf \i{symbol})}, the \term{name} of the block is \i{symbol}. The \term{class} of the \term{method} \term{object} that is created is that given by the method class option of the \term{generic function} on which the \term{method} is defined. If the \term{generic function} already has a \term{method} that agrees with the \term{method} being defined on \term{parameter specializers} and \term{qualifiers}, \macref{defmethod} replaces the existing \term{method} with the one now being defined. For a definition of agreement in this context. \seesection\SpecializerQualifierAgreement. The \term{parameter specializers} are derived from the \term{parameter specializer names} as described in \secref\IntroToMethods. The expansion of the \macref{defmethod} macro ``refers to'' each specialized parameter (see the description of \declref{ignore} within the description of \misc{declare}). This includes parameters that have an explicit \term{parameter specializer name} of \t. This means that a compiler warning does not occur if the body of the \term{method} does not refer to a specialized parameter, while a warning might occur if the body of the \term{method} does not refer to an unspecialized parameter. For this reason, a parameter that specializes on \t\ is not quite synonymous with an unspecialized parameter in this context. \issue{DEFMETHOD-DECLARATION-SCOPE:CORRESPONDS-TO-BINDINGS} Declarations at the head of the method body that apply to the method's \term{lambda variables} are treated as \term{bound declarations} whose \term{scope} is the same as the corresponding \term{bindings}. Declarations at the head of the method body that apply to the functional bindings of \funref{call-next-method} or \funref{next-method-p} apply to references to those functions within the method body \param{forms}. Any outer \term{bindings} of the \term{function names} \funref{call-next-method} and \funref{next-method-p}, and declarations associated with such \term{bindings} are \term{shadowed}\meaning{2} within the method body \param{forms}. The \term{scope} of \term{free declarations} at the head of the method body is the entire method body, which includes any implicit local function definitions but excludes \term{initialization forms} for the \term{lambda variables}. \endissue{DEFMETHOD-DECLARATION-SCOPE:CORRESPONDS-TO-BINDINGS} \issue{COMPILE-FILE-HANDLING-OF-TOP-LEVEL-FORMS:CLARIFY} \macref{defmethod} is not required to perform any compile-time side effects. In particular, the \term{methods} are not installed for invocation during compilation. An \term{implementation} may choose to store information about the \term{generic function} for the purposes of compile-time error-checking (such as checking the number of arguments on calls, or noting that a definition for the function name has been seen). \endissue{COMPILE-FILE-HANDLING-OF-TOP-LEVEL-FORMS:CLARIFY} \issue{DOCUMENTATION-FUNCTION-BUGS:FIX} \param{Documentation} is attached as a \term{documentation string} to the \term{method} \term{object}. \endissue{DOCUMENTATION-FUNCTION-BUGS:FIX} \label Examples:\None. \label Affected By:: The definition of the referenced \term{generic function}. \label Exceptional Situations:: If \i{function-name} names an \term{ordinary function}, a \term{macro}, or a \term{special operator}, an error \oftype{error} is signaled. If a \term{generic function} is currently named by {\it function-name}, the \term{lambda list} of the \term{method} must be congruent with the \term{lambda list} of the \term{generic function}, or an error \oftype{error} is signaled. %% gray addition %Also get an error for an undefined specializer class. \label See Also:: \macref{defgeneric}, \funref{documentation}, {\secref\IntroToMethods}, {\secref\GFMethodLambdaListCongruency}, {\secref\SpecializerQualifierAgreement}, {\secref\DocVsDecls} \label Notes:\None. \endissue{DECLS-AND-DOC} \endcom %%% ========== FIND-CLASS \begincom{find-class}\ftype{Accessor} \label Syntax:: \DefunWithValues find-class {symbol {\opt} errorp environment} {class} \Defsetf find-class {symbol {\opt} errorp environment} {new-class} \label Arguments and Values:: \param{symbol}---a \term{symbol}. \param{errorp}---a \term{generalized boolean}. \Default{\term{true}} \param{environment} -- same as the \keyref{environment} argument to macro expansion functions and is used to distinguish between compile-time and run-time environments. \issue{MACRO-ENVIRONMENT-EXTENT:DYNAMIC} The \keyref{environment} argument has \term{dynamic extent}; the consequences are undefined if the \keyref{environment} argument is referred to outside the \term{dynamic extent} of the macro expansion function. \endissue{MACRO-ENVIRONMENT-EXTENT:DYNAMIC} %!!! Default? \param{class}---a \term{class} \term{object}, or \nil. \label Description:: Returns the \term{class} \term{object} named by the \param{symbol} in the \param{environment}. If there is no such \term{class}, \nil\ is returned if \param{errorp} is \term{false}; otherwise, if \param{errorp} is \term{true}, an error is signaled. The \term{class} associated with a particular \term{symbol} can be changed by using \macref{setf} with \funref{find-class}; \issue{SETF-FIND-CLASS:ALLOW-NIL} or, if the new \term{class} given to \macref{setf} is \nil, the \term{class} association is removed (but the \term{class} \term{object} itself is not affected). \endissue{SETF-FIND-CLASS:ALLOW-NIL} The results are undefined if the user attempts to change \issue{SETF-FIND-CLASS:ALLOW-NIL} or remove \endissue{SETF-FIND-CLASS:ALLOW-NIL} the \term{class} associated with a \term{symbol} that is defined as a \term{type specifier} in this standard. \Seesection\IntegratingTypesAndClasses. When using \SETFof{find-class}, any \term{errorp} argument is \term{evaluated} for effect, but any \term{values} it returns are ignored; the \param{errorp} \term{parameter} is permitted primarily so that the \param{environment} \term{parameter} can be used. The \param{environment} might be used to distinguish between a compile-time and a run-time environment. \label Examples:\None. \label Affected By:\None. \label Exceptional Situations:: If there is no such \term{class} and \param{errorp} is \term{true}, \funref{find-class} signals an error \oftype{error}. \label See Also:: \macref{defmacro}, {\secref\IntegratingTypesAndClasses} \label Notes:\None. \endcom %%% ========== NEXT-METHOD-P \begincom{next-method-p}\ftype{Local Function} \label Syntax:: \DefunWithValues next-method-p {\noargs} {generalized-boolean} \label Arguments and Values:: \param{generalized-boolean}---a \term{generalized boolean}. \label Description:: The locally defined function \funref{next-method-p} can be used \issue{METHOD-INITFORM:FORBID-CALL-NEXT-METHOD} within the body \term{forms} (but not the \term{lambda list}) \endissue{METHOD-INITFORM:FORBID-CALL-NEXT-METHOD} defined by a \term{method-defining form} to determine whether a next \term{method} exists. \Thefunction{next-method-p} has \term{lexical scope} and \term{indefinite extent}. \issue{LEXICAL-CONSTRUCT-GLOBAL-DEFINITION:UNDEFINED} Whether or not \funref{next-method-p} is \term{fbound} in the \term{global environment} is \term{implementation-dependent}; however, the restrictions on redefinition and \term{shadowing} of \funref{next-method-p} are the same as for \term{symbols} in \thepackage{common-lisp} which are \term{fbound} in the \term{global environment}. The consequences of attempting to use \funref{next-method-p} outside of a \term{method-defining form} are undefined. \endissue{LEXICAL-CONSTRUCT-GLOBAL-DEFINITION:UNDEFINED} \label Examples:\None. \label Affected By:\None. \label Exceptional Situations:\None. \label See Also:: \funref{call-next-method}, \macref{defmethod}, \macref{call-method} \label Notes:\None. \endcom %%% ========== CALL-METHOD %%% ========== MAKE-METHOD %!!! ACW wonders if one of these is a Local Function. \begincom{call-method, make-method}\ftype{Local Macro} \label Syntax:: \DefmacWithValues call-method {method {\optional} next-method-list} {\starparam{result}} \DefmacWithValues make-method {form} {method-object} \label Arguments and Values:: % Moon notes that arguments are not evaluated. \param{method}---a \term{method} \term{object}, or a \term{list} (see below); \noeval. \param{method-object}---a \term{method} \term{object}. \param{next-method-list}---a \term{list} of \param{method} \term{objects}; \noeval. \param{results}---the \term{values} returned by the \term{method} invocation. \label Description:: The macro \macref{call-method} is used in method combination. It hides the \term{implementation-dependent} details of how \term{methods} are called. The macro \macref{call-method} has \term{lexical scope} and can only be used within an \term{effective method} \term{form}. \editornote{KMP: This next paragraph still needs some work.}%!!! \issue{LEXICAL-CONSTRUCT-GLOBAL-DEFINITION:UNDEFINED} Whether or not \macref{call-method} is \term{fbound} in the \term{global environment} is \term{implementation-dependent}; however, the restrictions on redefinition and \term{shadowing} of \macref{call-method} are the same as for \term{symbols} in \thepackage{common-lisp} which are \term{fbound} in the \term{global environment}. The consequences of attempting to use \macref{call-method} outside of an \term{effective method} \term{form} are undefined. \endissue{LEXICAL-CONSTRUCT-GLOBAL-DEFINITION:UNDEFINED} % Description of arguments in this paragraph changed by Moon: % Description of next-methods in this paragraph shortened by Moon: The macro \macref{call-method} invokes the specified \term{method}, supplying it with arguments and with definitions for \funref{call-next-method} and for \funref{next-method-p}. If the invocation of \macref{call-method} is lexically inside of a \funref{make-method}, the arguments are those that were supplied to that method. Otherwise the arguments are those that were supplied to the generic function. The definitions of \funref{call-next-method} and \funref{next-method-p} rely on the specified \param{next-method-list}. If \param{method} is a \term{list}, the first element of the \term{list} must be the symbol \funref{make-method} and the second element must be a \term{form}. Such a \term{list} specifies a \term{method} \term{object} whose \term{method} function has a body that is the given \term{form}. \param{Next-method-list} can contain \term{method} \term{objects} or \term{lists}, the first element of which must be the symbol \funref{make-method} and the second element of which must be a \term{form}. % Added by Moon: Those are the only two places where \funref{make-method} can be used. The \term{form} used with \funref{make-method} is evaluated in the \term{null lexical environment} augmented with a local macro definition for \macref{call-method} and with bindings named by symbols not \term{accessible} from \thepackage{common-lisp-user}. The \funref{call-next-method} function available to \param{method} will call the first \term{method} in \param{next-method-list}. The \funref{call-next-method} function available in that \term{method}, in turn, will call the second \term{method} in \param{next-method-list}, and so on, until the list of next \term{methods} is exhausted. %%--Changed in drafting committee by Moon If \param{next-method-list} is not supplied, the \funref{call-next-method} function available to \param{method} signals an error \oftype{control-error} and the \funref{next-method-p} function available to \param{method} returns {\nil}. \label Examples:: %!!! Barmar: This desperately needs examples. % I have a hard time understanding the use of MAKE-METHOD. \label Affected By:\None. \label Exceptional Situations:\None. \label See Also:: \funref{call-next-method}, \macref{define-method-combination}, \funref{next-method-p} \label Notes:\None. \endcom %%% ========== CALL-NEXT-METHOD \begincom{call-next-method}\ftype{Local Function} \label Syntax:: \DefunWithValues call-next-method {{\rest} args} {\starparam{result}} \label Arguments and Values:: \param{arg}---an \term{object}. % These are objects that are appropriate as args to the methods. \param{results}---the \term{values} returned by the \term{method} it calls. \label Description:: \Thefunction{call-next-method} can be used \issue{METHOD-INITFORM:FORBID-CALL-NEXT-METHOD} within the body \term{forms} (but not the \term{lambda list}) \endissue{METHOD-INITFORM:FORBID-CALL-NEXT-METHOD} of a \term{method} defined by a \term{method-defining form} to call the \term{next method}. If there is no next \term{method}, the generic function \funref{no-next-method} is called. The type of method combination used determines which \term{methods} can invoke \funref{call-next-method}. The standard \term{method combination} type allows \funref{call-next-method} to be used within primary \term{methods} and \term{around methods}. %%Barmar thinks this is not needed because it is said elsewhere (ch4.1). -kmp 22-Dec-90 % The standard % \term{method combination} % type defines the next \term{method} as follows: % % \beginlist % \itemitem{\bull} % If \funref{call-next-method} is used in an \term{around method}, % the next \term{method} is the next most specific \term{around method}, if one is % applicable. % % \itemitem{\bull} % If there are no \term{around methods} at all or if % \funref{call-next-method} is called by the least specific \term{around method}, % other \term{methods} are called as follows: % \beginlist % \itemitem{--} All the \term{before methods} are called, in % most-specific-first order. \Thefunction{call-next-method} % cannot be used in \term{before methods}. % % \itemitem{--} % The most specific primary \term{method} is called. Inside the body of a % primary \term{method}, \funref{call-next-method} can be used to pass control to % the next most specific primary \term{method}. The generic function % \funref{no-next-method} is called if \funref{call-next-method} is used and there % are no more primary \term{methods}. % % \itemitem{--} All the \term{after methods} are called in % most-specific-last order. \Thefunction{call-next-method} % cannot be used in \term{after methods}. % % \endlist % \endlist % For generic functions using a type of method combination defined by the short form of \macref{define-method-combination}, \funref{call-next-method} can be used in \term{around methods} only. When \funref{call-next-method} is called with no arguments, it passes the current \term{method}'s original arguments to the next \term{method}. Neither argument defaulting, nor using \specref{setq}, nor rebinding variables with the same \term{names} as parameters of the \term{method} affects the values \funref{call-next-method} passes to the \term{method} it calls. % A sentence was removed here by Moon since it was duplicated below, and another % sentence was moved to be next to the duplicate: When \funref{call-next-method} is called with arguments, the \term{next method} is called with those arguments. If \funref{call-next-method} is called with arguments but omits optional arguments, the \term{next method} called defaults those arguments. % Further computation is possible after \funref{call-next-method} returns. \Thefunction{call-next-method} returns any \term{values} that are returned by the \term{next method}. \Thefunction{call-next-method} has \term{lexical scope} and \term{indefinite extent} and can only be used within the body of a \term{method} defined by a \term{method-defining form}. \issue{LEXICAL-CONSTRUCT-GLOBAL-DEFINITION:UNDEFINED} Whether or not \funref{call-next-method} is \term{fbound} in the \term{global environment} is \term{implementation-dependent}; however, the restrictions on redefinition and \term{shadowing} of \funref{call-next-method} are the same as for \term{symbols} in \thepackage{common-lisp} which are \term{fbound} in the \term{global environment}. The consequences of attempting to use \funref{call-next-method} outside of a \term{method-defining form} are undefined. \endissue{LEXICAL-CONSTRUCT-GLOBAL-DEFINITION:UNDEFINED} \label Examples:\None. \label Affected By:: \macref{defmethod}, \macref{call-method}, \funref{define-method-combination}. \label Exceptional Situations:: % Grammar improved by Moon: %% Removed per X3J13. -kmp 05-Oct-93 % If \funref{call-next-method} is used in a \term{method} whose % \term{method combination} does not support it, % an error \oftype{control-error} is \term{signaled}. When providing arguments to \funref{call-next-method}, the following rule must be satisfied or an error \oftype{error} %% "is" => "should be" per X3J13. -kmp 05-Oct-93 %is should be signaled: the ordered set of \term{applicable methods} for a changed set of arguments for \funref{call-next-method} must be the same as the ordered set of \term{applicable methods} for the original arguments to the \term{generic function}. Optimizations of the error checking are possible, but they must not change the semantics of \funref{call-next-method}. \label See Also:: \macref{define-method-combination}, \macref{defmethod}, \funref{next-method-p}, \funref{no-next-method}, \macref{call-method}, {\secref\MethodSelectionAndCombination}, {\secref\StdMethComb}, {\secref\BuiltInMethCombTypes} \label Notes:\None. \endcom %%% ========== COMPUTE-APPLICABLE-METHODS \begincom{compute-applicable-methods}\ftype{Standard Generic Function} \issue{COMPUTE-APPLICABLE-METHODS:GENERIC} \label Syntax:: \DefgenWithValues compute-applicable-methods {generic-function function-arguments} {methods} \label Method Signatures:: \Defmeth compute-applicable-methods {\specparam{generic-function}{standard-generic-function}} \endissue{COMPUTE-APPLICABLE-METHODS:GENERIC} \label Arguments and Values:: \param{generic-function}---a \term{generic function}. \param{function-arguments}---a \term{list} of arguments for the \param{generic-function}. \param{methods}---a \term{list} of \term{method} \term{objects}. \label Description:: Given a \param{generic-function} and a set of \param{function-arguments}, the function \funref{compute-applicable-methods} returns the set of \term{methods} that are applicable for those arguments sorted according to precedence order. \Seesection\MethodSelectionAndCombination. \label Affected By:: \macref{defmethod} \label Exceptional Situations:\None. \label See Also:: {\secref\MethodSelectionAndCombination} \label Notes:\None. \endcom %%% ========== DEFINE-METHOD-COMBINATION \begincom{define-method-combination}\ftype{Macro} \issue{DECLS-AND-DOC} \label Syntax:: % 88-002R p.2-34 said "new method combination object" was returned, but it's wrong, % method-combination objects are created by the defgeneric :method-combination option. % See 88-002R p.1-28. --Moon % The "name" is returned. % Barrett didn't believe this at first, but now does. % Consensus comes slowly. \DefmacWithValuesNewline define-method-combination {name \interleave{\down{short-form-option}}} {name} \DefmacWithValuesNewline define-method-combination {\vtop{\hbox{name lambda-list} \hbox{\paren{\starparam{method-group-specifier}}} \hbox{\brac{\paren{\kwd{arguments} . args-lambda-list}}} \hbox{\brac{\paren{\kwd{generic-function} generic-function-symbol}}} \hbox{\DeclsAndDoc} \hbox{\starparam{form}}}} {name} \auxbnf{short-form-option}{\kwd{documentation} \param{documentation} | \CR \kwd{identity-with-one-argument} \param{identity-with-one-argument} |\CR \kwd{operator} \param{operator}} \auxbnf{method-group-specifier}{\paren{name \curly{\plusparam{qualifier-pattern} $\vert$ predicate} \interleave{\down{long-form-option}}}} \auxbnf{long-form-option}{\kwd{description} \param{description} |\CR \kwd{order} \param{order} |\CR \kwd{required} \param{required-p}} \label Arguments and Values:: \param{args-lambda-list}---% %Moon thought :arguments for DEFINE-METHOD-COMBINATION took an ordinary lambda list, %but Barrett (comment #3, first public review) observes that &whole is permissible. %Time to make a new kind of list. a \term{define-method-combination arguments lambda list}. \param{declaration}---a \misc{declare} \term{expression}; \noeval. \param{description}---a \term{format control}. \param{documentation}---a \term{string}; \noeval. \param{forms}---an \term{implicit progn} that must compute and return the \term{form} that specifies how the \term{methods} are combined, that is, the \term{effective method}. \param{generic-function-symbol}---a \term{symbol}. \param{identity-with-one-argument}---a \term{generalized boolean}. \param{lambda-list}---\term{ordinary lambda list}. \param{name}---a \term{symbol}. Non-\term{keyword}, \term{non-nil} \term{symbols} are usually used. \param{operator}---an \term{operator}. \param{Name} and \param{operator} are often the \term{same} \term{symbol}. This is the default, but it is not required. \param{order}---\kwd{most-specific-first} or \kwd{most-specific-last}; \eval. %Not a function designator? \param{predicate}---a \term{symbol} that names a \term{function} of one argument that returns a \term{generalized boolean}. \param{qualifier-pattern}---a \term{list}, or the \term{symbol} \misc{*}. \param{required-p}---a \term{generalized boolean}. \label Description:: The macro \macref{define-method-combination} is used to define new types of method combination. There are two forms of \macref{define-method-combination}. The short form is a simple facility for the cases that are expected to be most commonly needed. The long form is more powerful but more verbose. It resembles \macref{defmacro} in that the body is an expression, usually using backquote, that computes a \term{form}. Thus arbitrary control structures can be implemented. The long form also allows arbitrary processing of method \term{qualifiers}. %In both the short and long forms, \param{name} is a symbol. By convention, %non-keyword, \term{non-nil} symbols are usually used. \beginlist \itemitem{{\bf Short Form}} The short form syntax of \macref{define-method-combination} is recognized when the second \term{subform} is a \term{non-nil} symbol or is not present. When the short form is used, \param{name} is defined as a type of method combination that produces a Lisp form \f{({\param{operator} \param{method-call} \param{method-call} $\ldots$})}. The \param{operator} is a \term{symbol} that can be the \term{name} of a \term{function}, \term{macro}, or \term{special operator}. The \param{operator} can be supplied by a keyword option; it defaults to \param{name}. Keyword options for the short form are the following: \beginlist \itemitem{\bull} The \kwd{documentation} option is used to document the method-combination type; see description of long form below. \itemitem{\bull} The \kwd{identity-with-one-argument} option enables an optimization when its value is \term{true} (the default is \term{false}). If there is exactly one applicable method and it is a primary method, that method serves as the effective method and \param{operator} is not called. This optimization avoids the need to create a new effective method and avoids the overhead of a \term{function} call. This option is designed to be used with operators such as \specref{progn}, \macref{and}, \funref{$+$}, and \funref{max}. \itemitem{\bull} The \kwd{operator} option specifies the \term{name} of the operator. The \param{operator} argument is a \term{symbol} that can be the \term{name} of a \term{function}, \term{macro}, or \term{special form}. %By convention, \param{name} and %\param{operator} are often the same symbol. This is the default, %but it is not required. \endlist %None of the \term{subforms} is evaluated. These types of method combination require exactly one \term{qualifier} per method. An error is signaled if there are applicable methods with no \term{qualifiers} or with \term{qualifiers} that are not supported by the method combination type. A method combination procedure defined in this way recognizes two roles for methods. A method whose one \term{qualifier} is the symbol naming this type of method combination is defined to be a primary method. At least one primary method must be applicable or an error is signaled. A method with \kwd{around} as its one \term{qualifier} is an auxiliary method that behaves the same as an \term{around method} in standard method combination. \Thefunction{call-next-method} can only be used in \term{around methods}; it cannot be used in primary methods defined by the short form of the \macref{define-method-combination} macro. A method combination procedure defined in this way accepts an optional argument named \param{order}, which defaults to \kwd{most-specific-first}. A value of \kwd{most-specific-last} reverses the order of the primary methods without affecting the order of the auxiliary methods. The short form automatically includes error checking and support for \term{around methods}. For a discussion of built-in method combination types, \seesection\BuiltInMethCombTypes. \itemitem{{\bf Long Form}} The long form syntax of \macref{define-method-combination} is recognized when the second \term{subform} is a list. The \param{lambda-list} receives any arguments provided after the \term{name} of the method combination type in the \kwd{method-combination} option to \macref{defgeneric}. A list of method group specifiers follows. Each specifier selects a subset of the applicable methods to play a particular role, either by matching their \term{qualifiers} against some patterns or by testing their \term{qualifiers} with a \param{predicate}. These method group specifiers define all method \term{qualifiers} that can be used with this type of method combination. % Removed by Moon as the same information is repeated below %If an applicable %method does not fall into any method group, the system signals the error %that the method is invalid for the kind of method combination in use. %%Rewritten per Barmar. -kmp 28-Dec-90 %Each method group specifier names a variable. The \term{car} of each \param{method-group-specifier} is a \term{symbol} which \term{names} a \term{variable}. During the execution of the \term{forms} in the body of \macref{define-method-combination}, this \term{variable} is bound to a list of the \term{methods} in the method group. The \term{methods} in this list occur in the order specified by the \kwd{order} option. If \param{qualifier-pattern} is a \term{symbol} it must be \misc{*}. A method matches a \param{qualifier-pattern} if the method's list of \term{qualifiers} is \funref{equal} to the \param{qualifier-pattern} (except that the symbol \misc{*} in a \param{qualifier-pattern} matches anything). Thus a \param{qualifier-pattern} can be one of the following: the \term{empty list}, which matches \term{unqualified methods}; the symbol \misc{*}, which matches all methods; a true list, which matches methods with the same number of \term{qualifiers} as the length of the list when each \term{qualifier} matches the corresponding list element; or a dotted list that ends in the symbol \misc{*} (the \misc{*} matches any number of additional \term{qualifiers}). Each applicable method is tested against the \param{qualifier-patterns} and \param{predicates} in left-to-right order. As soon as a \param{qualifier-pattern} matches or a \param{predicate} returns true, the method becomes a member of the corresponding method group and no further tests are made. Thus if a method could be a member of more than one method group, it joins only the first such group. If a method group has more than one \param{qualifier-pattern}, a method need only satisfy one of the \param{qualifier-patterns} to be a member of the group. The \term{name} of a \param{predicate} function can appear instead of \param{qualifier-patterns} in a method group specifier. The \param{predicate} is called for each method that has not been assigned to an earlier method group; it is called with one argument, the method's \term{qualifier} \term{list}. The \param{predicate} should return true if the method is to be a member of the method group. A \param{predicate} can be distinguished from a \param{qualifier-pattern} because it is a \term{symbol} other than \nil\ or \misc{*}. % Wording improved --Moon If there is an applicable method that does not fall into any method group, \thefunction{invalid-method-error} is called. Method group specifiers can have keyword options following the \term{qualifier} patterns or predicate. Keyword options can be distinguished from additional \term{qualifier} patterns because they are neither lists nor the symbol \misc{*}. The keyword options are as follows: \beginlist \itemitem{\bull} The \kwd{description} option is used to provide a description of the role of methods in the method group. Programming environment tools use {\tt (apply \#'format stream \param{format-control} (method-qualifiers \param{method}))} to print this description, which is expected to be concise. This keyword option allows the description of a method \term{qualifier} to be defined in the same module that defines the meaning of the method \term{qualifier}. In most cases, \param{format-control} will not contain any \funref{format} directives, but they are available for generality. If \kwd{description} is not supplied, a default description is generated based on the variable name and the \term{qualifier} patterns and on whether this method group includes the \term{unqualified methods}. \itemitem{\bull} The \kwd{order} option specifies the order of methods. The \param{order} argument is a \term{form} that evaluates to \kwd{most-specific-first} or \kwd{most-specific-last}. If it evaluates to any other value, an error is signaled. %This keyword option is a %convenience and does not add any expressive power. If \kwd{order} is not supplied, it defaults to \kwd{most-specific-first}. \itemitem{\bull} The \kwd{required} option specifies whether at least one method in this method group is required. If its value is \term{true} and the method group is empty (that is, no applicable methods match the \term{qualifier} patterns or satisfy the predicate), an error is signaled. %This keyword option is a convenience and does not %add any expressive power. If \kwd{required} is not supplied, it defaults to \nil. \endlist The use of method group specifiers provides a convenient syntax to select methods, to divide them among the possible roles, and to perform the necessary error checking. It is possible to perform further filtering of methods in the body \term{forms} by using normal list-processing operations and the functions \funref{method-qualifiers} and \funref{invalid-method-error}. It is permissible to use \specref{setq} on the variables named in the method group specifiers and to bind additional variables. It is also possible to bypass the method group specifier mechanism and do everything in the body \term{forms}. This is accomplished by writing a single method group with \misc{*} as its only \param{qualifier-pattern}; the variable is then bound to a \term{list} of all of the \term{applicable methods}, in most-specific-first order. % Modified by Moon to clarify lexical environment: The body \param{forms} compute and return the \term{form} that specifies how the methods are combined, that is, the effective method. The effective method is evaluated in the \term{null lexical environment} augmented with a local macro definition for \funref{call-method} and with bindings named by symbols not \term{accessible} from \thepackage{common-lisp-user}. Given a method object in one of the \term{lists} produced by the method group specifiers and a \term{list} of next methods, \funref{call-method} will invoke the method such that \funref{call-next-method} has available the next methods. When an effective method has no effect other than to call a single method, some implementations employ an optimization that uses the single method directly as the effective method, thus avoiding the need to create a new effective method. This optimization is active when the effective method form consists entirely of an invocation of the \funref{call-method} macro whose first \term{subform} is a method object and whose second \term{subform} is \nil\ or unsupplied. Each \macref{define-method-combination} body is responsible for stripping off redundant invocations of \specref{progn}, \macref{and}, \macref{multiple-value-prog1}, and the like, if this optimization is desired. % One sentence was removed and replaced by Moon, since the specification % about congruence was excessively vague. Also discuss the consequences % of modifying arguments: The list {\tt (:arguments . \param{lambda-list})} can appear before any declarations or \term{documentation string}. This form is useful when the method combination type performs some specific behavior as part of the combined method and that behavior needs access to the arguments to the \term{generic function}. Each parameter variable defined by \param{lambda-list} is bound to a \term{form} that can be inserted into the effective method. When this \term{form} is evaluated during execution of the effective method, its value is the corresponding argument to the \term{generic function}; the consequences of using such a \term{form} as the \param{place} in a \macref{setf} \term{form} are undefined. \issue{METHOD-COMBINATION-ARGUMENTS:CLARIFY} %If \param{lambda-list} is not congruent to the %generic function's \term{lambda list}, additional ignored parameters are %automatically inserted until it is congruent. % If the arguments supplied to the \term{generic function} do not % match \param{lambda-list}, extra arguments are ignored and missing % arguments are defaulted to \nil\. % Thus it is permissible % for \param{lambda-list} to receive fewer arguments than the number of % required arguments for the \term{generic function}. Argument correspondence is computed by dividing the \kwd{arguments} \param{lambda-list} and the \term{generic function} \param{lambda-list} into three sections: the \term{required parameters}, the \term{optional parameters}, and the \term{keyword} and \term{rest parameters}. The \term{arguments} supplied to the \term{generic function} for a particular \term{call} are also divided into three sections; the required \term{arguments} section contains as many \term{arguments} as the \term{generic function} has \term{required parameters}, the optional \term{arguments} section contains as many arguments as the \term{generic function} has \term{optional parameters}, and the keyword/rest \term{arguments} section contains the remaining arguments. Each \term{parameter} in the required and optional sections of the \kwd{arguments} \param{lambda-list} accesses the argument at the same position in the corresponding section of the \term{arguments}. If the section of the \kwd{arguments} \param{lambda-list} is shorter, extra \term{arguments} are ignored. If the section of the \kwd{arguments} \param{lambda-list} is longer, excess \term{required parameters} are bound to forms that evaluate to \nil\ and excess \term{optional parameters} are \term{bound} to their initforms. The \term{keyword parameters} and \term{rest parameters} in the \kwd{arguments} \param{lambda-list} access the keyword/rest section of the \term{arguments}. If the \kwd{arguments} \param{lambda-list} contains \keyref{key}, it behaves as if it also contained \keyref{allow-other-keys}. In addition, \keyref{whole} \param{var} can be placed first in the \kwd{arguments} \param{lambda-list}. It causes \param{var} to be \term{bound} to a \term{form} that \term{evaluates} to a \term{list} of all of the \term{arguments} supplied to the \term{generic function}. This is different from \keyref{rest} because it accesses all of the arguments, not just the keyword/rest \term{arguments}. \endissue{METHOD-COMBINATION-ARGUMENTS:CLARIFY} Erroneous conditions detected by the body should be reported with \funref{method-combination-error} or \funref{invalid-method-error}; these \term{functions} add any necessary contextual information to the error message and will signal the appropriate error. The body \param{forms} are evaluated inside of the \term{bindings} created by the \term{lambda list} and method group specifiers. \reviewer{Barmar: Are they inside or outside the :ARGUMENTS bindings?} Declarations at the head of the body are positioned directly inside of \term{bindings} created by the \term{lambda list} and outside of the \term{bindings} of the method group variables. Thus method group variables cannot be declared in this way. \specref{locally} may be used around the body, however. Within the body \param{forms}, \param{generic-function-symbol} is bound to the \term{generic function} \term{object}. \issue{DOCUMENTATION-FUNCTION-BUGS:FIX} \param{Documentation} is attached as a \term{documentation string} to \param{name} (as kind \specref{method-combination}) and to the \term{method combination} \term{object}. \endissue{DOCUMENTATION-FUNCTION-BUGS:FIX} % Removed by Moon, appears to be redundant with what was stated earlier: %The functions \funref{method-combination-error} and %\funref{invalid-method-error} can be called from the body \param{forms} or %from \term{functions} called by the body \param{forms}. The actions of these %two \term{functions} can depend on \term{implementation-dependent} dynamic variables %automatically bound before the generic function %\funref{compute-effective-method} is called. Note that two methods with identical specializers, but with different \term{qualifiers}, are not ordered by the algorithm described in Step 2 of the method selection and combination process described in \secref\MethodSelectionAndCombination. Normally the two methods play different roles in the effective method because they have different \term{qualifiers}, and no matter how they are ordered in the result of Step 2, the effective method is the same. If the two methods play the same role and their order matters, \reviewer{Barmar: How does the system know when the order matters?} an error is signaled. This happens as part of the \term{qualifier} pattern matching in \macref{define-method-combination}. \endlist \issue{DEFINE-METHOD-COMBINATION:CLARIFY} If a \macref{define-method-combination} \term{form} appears as a \term{top level form}, the \term{compiler} must make the \term{method combination} \term{name} be recognized as a valid \term{method combination} \term{name} in subsequent \macref{defgeneric} \term{forms}. However, the \term{method combination} is executed no earlier than when the \macref{define-method-combination} \term{form} is executed, and possibly as late as the time that \term{generic functions} that use the \term{method combination} are executed. \endissue{DEFINE-METHOD-COMBINATION:CLARIFY} \label Examples:: %% Examples changed by Moon to reflect that the second argument of %% call-method is unsupplied when call-next-method is not allowed Most examples of the long form of \macref{define-method-combination} also illustrate the use of the related \term{functions} that are provided as part of the declarative method combination facility. \code ;;; Examples of the short form of define-method-combination (define-method-combination and :identity-with-one-argument t) (defmethod func and ((x class1) y) ...) ;;; The equivalent of this example in the long form is: (define-method-combination and (&optional (order :most-specific-first)) ((around (:around)) (primary (and) :order order :required t)) (let ((form (if (rest primary) `(and ,@(mapcar #'(lambda (method) `(call-method ,method)) primary)) `(call-method ,(first primary))))) (if around `(call-method ,(first around) (,@(rest around) (make-method ,form))) form))) ;;; Examples of the long form of define-method-combination ;The default method-combination technique (define-method-combination standard () ((around (:around)) (before (:before)) (primary () :required t) (after (:after))) (flet ((call-methods (methods) (mapcar #'(lambda (method) `(call-method ,method)) methods))) (let ((form (if (or before after (rest primary)) `(multiple-value-prog1 (progn ,@(call-methods before) (call-method ,(first primary) ,(rest primary))) ,@(call-methods (reverse after))) `(call-method ,(first primary))))) (if around `(call-method ,(first around) (,@(rest around) (make-method ,form))) form)))) ;A simple way to try several methods until one returns non-nil (define-method-combination or () ((methods (or))) `(or ,@(mapcar #'(lambda (method) `(call-method ,method)) methods))) ;A more complete version of the preceding (define-method-combination or (&optional (order ':most-specific-first)) ((around (:around)) (primary (or))) ;; Process the order argument (case order (:most-specific-first) (:most-specific-last (setq primary (reverse primary))) (otherwise (method-combination-error "~S is an invalid order.~@ :most-specific-first and :most-specific-last are the possible values." order))) ;; Must have a primary method (unless primary (method-combination-error "A primary method is required.")) ;; Construct the form that calls the primary methods (let ((form (if (rest primary) `(or ,@(mapcar #'(lambda (method) `(call-method ,method)) primary)) `(call-method ,(first primary))))) ;; Wrap the around methods around that form (if around `(call-method ,(first around) (,@(rest around) (make-method ,form))) form))) ;The same thing, using the :order and :required keyword options (define-method-combination or (&optional (order ':most-specific-first)) ((around (:around)) (primary (or) :order order :required t)) (let ((form (if (rest primary) `(or ,@(mapcar #'(lambda (method) `(call-method ,method)) primary)) `(call-method ,(first primary))))) (if around `(call-method ,(first around) (,@(rest around) (make-method ,form))) form))) ;This short-form call is behaviorally identical to the preceding (define-method-combination or :identity-with-one-argument t) ;Order methods by positive integer qualifiers ;:around methods are disallowed to keep the example small (define-method-combination example-method-combination () ((methods positive-integer-qualifier-p)) `(progn ,@(mapcar #'(lambda (method) `(call-method ,method)) (stable-sort methods #'< :key #'(lambda (method) (first (method-qualifiers method))))))) (defun positive-integer-qualifier-p (method-qualifiers) (and (= (length method-qualifiers) 1) (typep (first method-qualifiers) '(integer 0 *)))) ;;; Example of the use of :arguments (define-method-combination progn-with-lock () ((methods ())) (:arguments object) `(unwind-protect (progn (lock (object-lock ,object)) ,@(mapcar #'(lambda (method) `(call-method ,method)) methods)) (unlock (object-lock ,object)))) \endcode \label Affected By:\None. \label Side Effects:: \issue{COMPILE-FILE-HANDLING-OF-TOP-LEVEL-FORMS:CLARIFY} The \term{compiler} is not required to perform any compile-time side-effects. \endissue{COMPILE-FILE-HANDLING-OF-TOP-LEVEL-FORMS:CLARIFY} \label Exceptional Situations:: Method combination types defined with the short form require exactly one \term{qualifier} per method. An error \oftype{error} is signaled if there are applicable methods with no \term{qualifiers} or with \term{qualifiers} that are not supported by the method combination type. At least one primary method must be applicable or an error \oftype{error} is signaled. If an applicable method does not fall into any method group, the system signals an error \oftype{error} indicating that the method is invalid for the kind of method combination in use. If the value of the \kwd{required} option is \term{true} and the method group is empty (that is, no applicable methods match the \term{qualifier} patterns or satisfy the predicate), an error \oftype{error} is signaled. If the \kwd{order} option evaluates to a value other than \kwd{most-specific-first} or \kwd{most-specific-last}, an error \oftype{error} is signaled. \label See Also:: \funref{call-method}, \funref{call-next-method}, \funref{documentation}, \funref{method-qualifiers}, \funref{method-combination-error}, \funref{invalid-method-error}, \macref{defgeneric}, {\secref\MethodSelectionAndCombination}, {\secref\BuiltInMethCombTypes}, {\secref\DocVsDecls} \label Notes:: % Added phrase to the end of this paragraph --Moon: The \kwd{method-combination} option of \macref{defgeneric} is used to specify that a \term{generic function} should use a particular method combination type. The first argument to the \kwd{method-combination} option is the \term{name} of a method combination type and the remaining arguments are options for that type. \endissue{DECLS-AND-DOC} \endcom %%% ========== FIND-METHOD \begincom{find-method}\ftype{Standard Generic Function} \label Syntax:: \DefgenWithValuesNewline find-method {generic-function method-qualifiers specializers {\opt} errorp} {method} \label Method Signatures:: \Defmeth find-method {\vtop{\hbox{\specparam{generic-function}{standard-generic-function}} \hbox{method-qualifiers specializers {\opt} errorp}}} \label Arguments and Values:: \param{generic-function}---a \term{generic function}. \param{method-qualifiers}---a \term{list}. \param{specializers}---a \term{list}. \param{errorp}---a \term{generalized boolean}. \Default{\term{true}} \param{method}---a \term{method} \term{object}, or \nil. \label Description:: The \term{generic function} \funref{find-method} takes a \term{generic function} and returns the \term{method} \term{object} that agrees on \term{qualifiers} and \term{parameter specializers} with the \param{method-qualifiers} and \param{specializers} arguments of \funref{find-method}. \param{Method-qualifiers} contains the method \term{qualifiers} for the \term{method}. The order of the method \term{qualifiers} is significant. For a definition of agreement in this context, \seesection\SpecializerQualifierAgreement. The \param{specializers} argument contains the parameter specializers for the \term{method}. It must correspond in length to the number of required arguments of the \term{generic function}, or an error is signaled. This means that to obtain the default \term{method} on a given \param{generic-function}, a \term{list} whose elements are \theclass{t} must be given. If there is no such \term{method} and \param{errorp} is \term{true}, \funref{find-method} signals an error. If there is no such \term{method} and \param{errorp} is \term{false}, \funref{find-method} returns \nil. \label Examples:: \code (defmethod some-operation ((a integer) (b float)) (list a b)) \EV # (find-method #'some-operation '() (mapcar #'find-class '(integer float))) \EV # (find-method #'some-operation '() (mapcar #'find-class '(integer integer))) \OUT Error: No matching method (find-method #'some-operation '() (mapcar #'find-class '(integer integer)) nil) \EV NIL \endcode \label Affected By:: \funref{add-method}, \macref{defclass}, \macref{defgeneric}, \macref{defmethod} \label Exceptional Situations:: If the \param{specializers} argument does not correspond in length to the number of required arguments of the \param{generic-function}, an an error \oftype{error} is signaled. If there is no such \term{method} and \param{errorp} is \term{true}, \funref{find-method} signals an error \oftype{error}. \label See Also:: {\secref\SpecializerQualifierAgreement} \label Notes:\None. \endcom %%% ========== ADD-METHOD \begincom{add-method}\ftype{Standard Generic Function} \label Syntax:: \DefgenWithValues add-method {generic-function method} {generic-function} \label Method Signatures:: \Defmeth add-method {\vtop{\hbox{\specparam{generic-function}{standard-generic-function}} \hbox{\specparam{method}{method}}}} \label Arguments and Values:: \param{generic-function}---a \term{generic function} \term{object}. \param{method}---a \term{method} \term{object}. \label Description:: The generic function \funref{add-method} adds a \term{method} to a \term{generic function}. If \param{method} agrees with an existing \term{method} of \param{generic-function} on \term{parameter specializers} and \term{qualifiers}, the existing \term{method} is replaced. %% Per X3J13. -kmp 05-Oct-93 \label Examples:\None. %!!! \label Affected By:\None. \label Exceptional Situations:: The \term{lambda list} of the method function of \param{method} must be congruent with the \term{lambda list} of \param{generic-function}, or an error \oftype{error} is signaled. If \param{method} is a \term{method} \term{object} of another \term{generic function}, an error \oftype{error} is signaled. \label See Also:: \macref{defmethod}, \macref{defgeneric}, \funref{find-method}, \funref{remove-method}, {\secref\SpecializerQualifierAgreement} \label Notes:\None. \endcom %%% ========== INITIALIZE-INSTANCE \begincom{initialize-instance}\ftype{Standard Generic Function} \label Syntax:: \issue{INITIALIZATION-FUNCTION-KEYWORD-CHECKING} \DefgenWithValues initialize-instance {instance {\rest} initargs {\key} {\allowotherkeys}} {instance} \endissue{INITIALIZATION-FUNCTION-KEYWORD-CHECKING} \label Method Signatures:: \Defmeth initialize-instance {\specparam{instance}{standard-object} {\rest} initargs} \label Arguments and Values:: \param{instance}---an \term{object}. \param{initargs}---a \term{defaulted initialization argument list}. \label Description:: Called by \funref{make-instance} to initialize a newly created \term{instance}. The generic function is called with the new \param{instance} and the \term{defaulted initialization argument list}. The system-supplied primary \term{method} on \funref{initialize-instance} initializes the \term{slots} of the \param{instance} with values according to the \param{initargs} and the \kwd{initform} forms of the \term{slots}. It does this by calling the generic function \funref{shared-initialize} with the following arguments: the \param{instance}, \t\ (this indicates that all \term{slots} for which no initialization arguments are provided should be initialized according to their \kwd{initform} forms), and the \param{initargs}. Programmers can define \term{methods} for \funref{initialize-instance} to specify actions to be taken when an instance is initialized. If only \term{after methods} are defined, they will be run after the system-supplied primary \term{method} for initialization and therefore will not interfere with the default behavior of \funref{initialize-instance}. \label Examples:\None. \label Affected By:\None. \label Exceptional Situations:\None. \label See Also:: \funref{shared-initialize}, \funref{make-instance}, \funref{slot-boundp}, \funref{slot-makunbound}, {\secref\ObjectCreationAndInit}, {\secref\InitargRules}, {\secref\DeclaringInitargValidity} \label Notes:\None. \endcom %%% ========== CLASS-NAME \begincom{class-name}\ftype{Standard Generic Function} \label Syntax:: \DefgenWithValues class-name {class} {name} \label Method Signatures:: \Defmeth class-name {\specparam{class}{class}} \label Arguments and Values:: \param{class}---a \term{class} \term{object}. \param{name}---a \term{symbol}. \label Description:: Returns the \term{name} of the given \param{class}. \label Examples:\None. \label Affected By:\None. \label Exceptional Situations:\None. \label See Also:: \funref{find-class}, {\secref\Classes} \label Notes:: If $S$ is a \term{symbol} such that $S =${\tt (class-name $C$)} and $C =${\tt (find-class $S$)}, then $S$ is the proper name of $C$. For further discussion, \seesection\Classes. The name of an anonymous \term{class} is \nil. \endcom %%% ========== (SETF CLASS-NAME) \begincom{(setf class-name)}\ftype{Standard Generic Function} \label Syntax:: \DefgenWithValues {(setf class-name)} {new-value class} {new-value} \label Method Signatures:: \Defmeth {(setf class-name)} {new-value \specparam{class}{class}} \label Arguments and Values:: \param{new-value}---a \term{symbol}. \param{class}---a \term{class}. \label Description:: The generic function \f{(setf class-name)} sets the name of a \param{class} object. %The name of \param{class} is set to \param{new-value}. \label Examples:\None. \label Affected By:\None. \label Exceptional Situations:\None. \label See Also:: \funref{find-class}, \term{proper name}, {\secref\Classes} %% Per X3J13. -kmp 05-Oct-93 \label Notes:\None. %This info is in the glossary and elsewhere. I added a cross reference above. -kmp 14-May-91 % If \i{S} is a symbol such that % \f{\i{S} = (class-name \i{C})} % and \f{\i{C} = (find-class \i{S})}, % then \i{S} is the \term{proper name} of \i{C}. %For further discussion, \seesection\Classes. \endcom %%% ========== CLASS-OF \begincom{class-of}\ftype{Function} \label Syntax:: \DefunWithValues class-of {object} {class} \label Arguments and Values:: \param{object}---an \term{object}. \param{class}---a \term{class} \term{object}. \label Description:: Returns the \term{class} of which the \param{object} is %"an instance" -> "a direct instance" -kmp 15-Jan-91 a \term{direct instance}. \label Examples:: \code (class-of 'fred) \EV # (class-of 2/3) \EV # (defclass book () ()) \EV # (class-of (make-instance 'book)) \EV # (defclass novel (book) ()) \EV # (class-of (make-instance 'novel)) \EV # (defstruct kons kar kdr) \EV KONS (class-of (make-kons :kar 3 :kdr 4)) \EV # \endcode \label Affected By:\None! \label Exceptional Situations:\None! \label See Also:: \funref{make-instance}, \funref{type-of} \label Notes:\None. \endcom %--------------------Object Errors-------------------- \begincom{unbound-slot}\ftype{Condition Type} \issue{UNDEFINED-VARIABLES-AND-FUNCTIONS:COMPROMISE} \label Class Precedence List:: \typeref{unbound-slot}, \typeref{cell-error}, \typeref{error}, \typeref{serious-condition}, \typeref{condition}, \typeref{t} \label Description:: The \term{object} having the unbound slot is initialized by \theinitkeyarg{instance} to \funref{make-condition}, and is \term{accessed} by \thefunction{unbound-slot-instance}. % \Thetype{unbound-slot} has an instance slot that can be % initialized using the \kwd{instance} keyword to \funref{make-condition}. \endissue{UNDEFINED-VARIABLES-AND-FUNCTIONS:COMPROMISE} The name of the cell (see \typeref{cell-error}) is the name of the slot. \label See Also:: \funref{cell-error-name}, \funref{unbound-slot-object}, {\secref\ConditionSystemConcepts} \endcom%{unbound-slot}\ftype{Condition Type} %%% ========== UNBOUND-SLOT-INSTANCE \begincom{unbound-slot-instance}\ftype{Function} \issue{UNDEFINED-VARIABLES-AND-FUNCTIONS:COMPROMISE} \label Syntax:: \DefunWithValues unbound-slot-instance {condition} {instance} \label Arguments and Values:: \param{condition}---a \term{condition} \oftype{unbound-slot}. \param{instance}---an \term{object}. \label Description:: Returns the instance which had the unbound slot in the \term{situation} represented by the \param{condition}. \label Examples:\None. \label Affected By:\None. \label Exceptional Situations:\None. \label See Also:: \funref{cell-error-name}, \typeref{unbound-slot}, {\secref\ConditionSystemConcepts} \label Notes:\None. %Shouldn't be needed. %It is an error to use \macref{setf} with \funref{unbound-slot-instance}. \endissue{UNDEFINED-VARIABLES-AND-FUNCTIONS:COMPROMISE} \endcom