X-Git-Url: http://repo.macrolet.net/gitweb/?a=blobdiff_plain;f=doc%2Fmanual%2Fbeyond-ansi.texinfo;h=2bb0ec6a04abb6913d934a2611ea1eaf81a5b371;hb=5fdb9edd71a21b3697ba6f407aca270060ef173c;hp=9cc2a9e45b5a06dfe85ec9650f00ae0be341599c;hpb=feea06ce0acba516d739867b23341509e9c36d50;p=sbcl.git diff --git a/doc/manual/beyond-ansi.texinfo b/doc/manual/beyond-ansi.texinfo index 9cc2a9e..2bb0ec6 100644 --- a/doc/manual/beyond-ansi.texinfo +++ b/doc/manual/beyond-ansi.texinfo @@ -47,18 +47,28 @@ are: @item @findex compute-effective-method @findex sb-mop:compute-effective-method -@code{compute-effective-method} only returns one value, not two; - -@item -@findex compute-slots -@findex sb-mop:compute-slots -@tindex funcallable-standard-class -@tindex sb-mop:funcallable-standard-class -the system-supplied @code{:around} method for @code{compute-slots} -specialized on @code{funcallable-standard-class} does not respect the -requested order from a user-supplied primary method. +@code{compute-effective-method} only returns one value, not two. + +There is no record of what the second return value was meant to +indicate, and apparently no clients for it. @item +@tindex generic-function +@tindex standard-generic-function +@tindex funcallable-standard-object +@tindex sb-mop:funcallable-standard-object +@tindex standard-object +@tindex function +The direct superclasses of @code{sb-mop:funcallable-standard-object} are +@code{(function standard-object)}, not @code{(standard-object function)}. + +This is to ensure that the @code{standard-object} class is the last of +the standardized classes before @code{t} appearing in the class +precedence list of @code{generic-function} and +@code{standard-generic-function}, as required by section 1.4.4.5 of the +ANSI specification. + +@item @findex ensure-generic-function @findex generic-function-declarations @findex sb-mop:generic-function-declarations @@ -67,6 +77,10 @@ the arguments @code{:declare} and @code{:declarations} to argument defining the declarations to be stored and returned by @code{generic-function-declarations}. +Where AMOP specifies @code{:declarations} as the keyword argument to +@code{ensure-generic-function}, the Common Lisp standard specifies +@code{:declare}. Portable code should use @code{:declare}. + @item @findex validate-superclass @findex finalize-inheritance @@ -75,12 +89,159 @@ argument defining the declarations to be stored and returned by @tindex standard-class @tindex funcallable-standard-class @tindex sb-mop:funcallable-standard-class -although we obey the requirement in AMOP for @code{validate-superclass} -for @code{standard-class} and @code{funcallable-standard-class} to be -compatible metaclasses, we impose an additional requirement at class -finalization time: a class of metaclass -@code{funcallable-standard-class} must have @code{function} in its -superclasses, and a class of metaclass @code{standard-class} must not. +@tindex function +@findex sb-mop:class-prototype +@findex class-prototype +although SBCL obeys the requirement in AMOP that +@code{validate-superclass} should treat @code{standard-class} and +@code{funcallable-standard-class} as compatible metaclasses, we +impose an additional requirement at class finalization time: a class +of metaclass @code{funcallable-standard-class} must have +@code{function} in its superclasses, and a class of metaclass +@code{standard-class} must not. + +@findex typep +@findex class-of +@findex subtypep +After a class has been finalized, it is associated with a class +prototype which is accessible by a standard mop function +@code{sb-mop:class-prototype}. The user can then ask whether this +object is a @code{function} or not in several different ways: whether it +is a function according to @code{typep}; whether its @code{class-of} is +@code{subtypep} @code{function}, or whether @code{function} appears in +the superclasses of the class. The additional consistency requirement +comes from the desire to make all of these answers the same. + +The following class definitions are bad, and will lead to errors +either immediately or if an instance is created: +@lisp +(defclass bad-object (funcallable-standard-object) + () + (:metaclass standard-class)) +@end lisp +@lisp +(defclass bad-funcallable-object (standard-object) + () + (:metaclass funcallable-standard-class)) +@end lisp +The following definition is acceptable: +@lisp +(defclass mixin () + ((slot :initarg slot))) +(defclass funcallable-object (funcallable-standard-object mixin) + () + (:metaclass funcallable-standard-class)) +@end lisp +and leads to a class whose instances are funcallable and have one slot. + +@tindex funcallable-standard-object +@tindex sb-mop:funcallable-standard-object +Note that this requirement also applies to the class +@code{sb-mop:funcallable-standard-object}, which has metaclass +@code{sb-mop:funcallable-standard-class} rather than +@code{standard-class} as AMOP specifies. + +@item +the requirement that ``No portable class @math{C_p} may inherit, by +virtue of being a direct or indirect subclass of a specified class, any +slot for which the name is a symbol accessible in the +@code{common-lisp-user} package or exported by any package defined in +the ANSI Common Lisp standard.'' is interpreted to mean that the +standardized classes themselves should not have slots named by external +symbols of public packages. + +The rationale behind the restriction is likely to be similar to the ANSI +Common Lisp restriction on defining functions, variables and types named +by symbols in the Common Lisp package: preventing two independent pieces +of software from colliding with each other. + +@item +@findex slot-value-using-class +@findex sb-mop:slot-value-using-class +@findex (setf slot-value-using-class) +@findex (setf sb-mop:slot-value-using-class) +@findex slot-boundp-using-class +@findex sb-mop:slot-boundp-using-class +specializations of the @code{new-value} argument to @code{(setf +sb-mop:slot-value-using-class)} are not allowed: all user-defined +methods must have a specializer of the class @code{t}. + +This prohibition is motivated by a separation of layers: the +@code{slot-value-using-class} family of functions is intended for use in +implementing different and new slot allocation strategies, rather than +in performing application-level dispatching. Additionally, with this +requirement, there is a one-to-one mapping between metaclass, class and +slot-definition-class tuples and effective methods of @code{(setf +slot-value-using-class)}, which permits optimization of @code{(setf +slot-value-using-class)}'s discriminating function in the same manner as +for @code{slot-value-using-class} and @code{slot-boundp-using-class}. + +Note that application code may specialize on the @code{new-value} +argument of slot accessors. + +@item +@findex defclass +@findex ensure-class +@findex ensure-class-using-class +@findex sb-mop:ensure-class +@findex sb-mop:ensure-class-using-class +@findex find-class +@findex class-name +the class named by the @code{name} argument to @code{ensure-class}, if +any, is only redefined if it is the proper name of that class; +otherwise, a new class is created. + +This is consistent with the description of @code{ensure-class} in AMOP +as the functional version of @code{defclass}, which has this behaviour; +however, it is not consistent with the weaker requirement in AMOP, which +states that any class found by @code{find-class}, no matter what its +@code{class-name}, is redefined. + +@end itemize + +In addition, SBCL supports extensions to the Metaobject protocol from +AMOP; at present, they are: + +@itemize + +@item +@findex defmethod +@findex find-class +@findex intern-eql-specializer +@findex sb-mop:intern-eql-specializer +@findex make-method-specializers-form +@findex sb-pcl:make-method-specializers-form +@findex make-method-lambda +@findex sb-mop:make-method-lambda +compile-time support for generating specializer metaobjects from +specializer names in @code{defmethod} forms is provided by the +@code{make-method-specializers-form} function, which returns a form +which, when evaluated in the lexical environment of the +@code{defmethod}, returns a list of specializer metaobjects. This +operator suffers from similar restrictions to those affecting +@code{make-method-lambda}, namely that the generic function must be +defined when the @code{defmethod} form is expanded, so that the +correct method of @code{make-method-specializers-form} is invoked. +The system-provided method on @code{make-method-specializers-form} +generates a call to @code{find-class} for each symbol specializer +name, and a call to @code{intern-eql-specializer} for each @code{(eql +@var{x})} specializer name. + +@item +@findex find-method +@findex parse-specializer-using-class +@findex unparse-specializer-using-class +@findex sb-pcl:parse-specializer-using-class +@findex sb-pcl:unparse-specializer-using-class +run-time support for converting between specializer names and +specializer metaobjects, mostly for the purposes of +@code{find-method}, is provided by +@code{parse-specializer-using-class} and +@code{unparse-specializer-using-class}, which dispatch on their first +argument, the generic function associated with a method with the given +specializer. The system-provided methods on those methods convert +between classes and proper names and between lists of the form +@code{(eql @var{x})} and interned eql specializer objects. @end itemize @@ -94,6 +255,31 @@ the @code{sb-ext:posix-getenv} function. @include fun-sb-ext-posix-getenv.texinfo +External programs can be run with @code{sb-ext:run-program}. + +@include fun-sb-ext-run-program.texinfo + +@include fun-sb-ext-process-p.texinfo + +@include fun-sb-ext-process-input.texinfo + +@include fun-sb-ext-process-output.texinfo + +@include fun-sb-ext-process-error.texinfo + +@include fun-sb-ext-process-alive-p.texinfo + +@include fun-sb-ext-process-status.texinfo + +@include fun-sb-ext-process-wait.texinfo + +@include fun-sb-ext-process-exit-code.texinfo + +@include fun-sb-ext-process-core-dumped.texinfo + +@include fun-sb-ext-process-close.texinfo + +@include fun-sb-ext-process-kill.texinfo @node Customization Hooks for Users @comment node-name, next, previous, up