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Local Macro CALL-METHOD, MAKE-METHOD

Syntax:

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.

Description:

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.

Examples:

Affected By: None.

Exceptional Situations: None.

See Also:

call-next-method, define-method-combination, next-method-p

Notes: None.

The following X3J13 cleanup issue, not part of the specification, applies to this section:

- LEXICAL-CONSTRUCT-GLOBAL-DEFINITION:UNDEFINED

Copyright 1996-2005, LispWorks Ltd. All rights reserved.