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  ANSI Common Lisp   7 Objects   7.7 Dictionary of Objects

7.7.30 call-method, make-method Local Macro

call-method method &optional next-method-list    {result}*

make-method form    method-object

Arguments and Values:
method - a method object, or a list (see below); not evaluated.

method-object - a method object.

next-method-list - a list of method objects; not evaluated.

results - the values returned by the method invocation.

The macro call-method is used in method combination. It hides the implementation-dependent details of how methods are called. The macro call-method has lexical scope and can only be used within an effective method form.

Whether or not call-method is fbound in the global environment is implementation-dependent; however, the restrictions on redefinition and shadowing of call-method are the same as for symbols in the common-lisp package which are fbound in the global environment. The consequences of attempting to use call-method outside of an effective method form are undefined.

The macro call-method invokes the specified method, supplying it with arguments and with definitions for call-next-method and for next-method-p. If the invocation of call-method is lexically inside of a 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 call-next-method and next-method-p rely on the specified next-method-list.

If method is a list, the first element of the list must be the symbol make-method and the second element must be a form. Such a list specifies a method object whose method function has a body that is the given form.

Next-method-list can contain method objects or lists, the first element of which must be the symbol make-method and the second element of which must be a form.

Those are the only two places where make-method can be used. The form used with make-method is evaluated in the null lexical environment augmented with a local macro definition for call-method and with bindings named by symbols not accessible from the common-lisp-user package.

The call-next-method function available to method will call the first method in next-method-list. The call-next-method function available in that method, in turn, will call the second method in next-method-list, and so on, until the list of next methods is exhausted.

If next-method-list is not supplied, the call-next-method function available to method signals an error of type control-error and the next-method-p function available to method returns nil.


See Also:
call-next-method, define-method-combination, next-method-p

Allegro CL Implementation Details:

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