ANSI Common Lisp 7 Objects 7.6 Generic Functions and Methods 7.6.6 Method Selection and Combination
18.104.22.168 Declarative Method Combination
The macro define-method-combination defines new forms of method
combination. It provides a mechanism for customizing the production
of the effective method. The default procedure for producing an
effective method is described in Section 22.214.171.124 Determining the Effective Method.
There are two forms of
define-method-combination. The short form is a simple facility while
the long form is more powerful and more verbose. The long form
resembles defmacro in that the body is an expression that
computes a Lisp form; it provides mechanisms for implementing
arbitrary control structures within method combination and for
arbitrary processing of method qualifiers.