Common Lisp the Language, 2nd Edition


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28.1.7.4. Built-in Method Combination Types

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The Common Lisp Object System provides a set of built-in method combination types. To specify that a generic function is to use one of these method combination types, the name of the method combination type is given as the argument to the :method-combination option to defgeneric or to the :method-combination option to any of the other forms that specify generic function options.

The names of the built-in method combination types are +, and, append, list, max, min, nconc, or, progn, and standard.

The semantics of the standard built-in method combination type were described in section 28.1.7.2. The other built-in method combination types are called simple built-in method combination types.

The simple built-in method combination types act as though they were defined by the short form of define-method-combination. They recognize two roles for methods:

The semantics of the simple built-in method combination types are as follows:

The simple built-in method combination types require exactly one qualifier per method. An error is signaled if there are applicable methods with no qualifiers or with qualifiers that are not supported by the method combination type. An error is signaled if there are applicable :around methods and no applicable primary methods.
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