Common Lisp the Language, 2nd Edition

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## 28.1.7. Method Selection and Combination

When a generic function is called with particular arguments, it must determine the code to execute. This code is called the effective method for those arguments. The effective method is a combination of the applicable methods in the generic function. A combination of methods is a Lisp expression that contains calls to some or all of the methods. If a generic function is called and no methods apply, the generic function `no-applicable-method` is invoked.

When the effective method has been determined, it is invoked with the same arguments that were passed to the generic function. Whatever values it returns are returned as the values of the generic function.

- Determining the Effective Method
- Standard Method Combination
- Declarative Method Combination
- Built-in Method Combination Types