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Function ENSURE-GENERIC-FUNCTION

Syntax

  • ensure-generic-function function-name &key argument-precedence-order declare documentation environment generic-function-class lambda-list method-class method-combinationgeneric-function

Arguments and Values

  • function-name - a function name.
    • The keyword arguments correspond to the option arguments of defgeneric, except that the :method-class and :generic-function-class arguments can be class objects as well as names.
    • :method-combination - method combination object.
    • :environment - the same as the &environment argument to macro expansion functions and is used to distinguish between compile-time and run-time environments.
  • generic-function - a generic function object.

Description

The function ensure-generic-function is used to define a globally named generic function with no methods or to specify or modify options and declarations that pertain to a globally named generic function as a whole.

If function-name is not fbound in the global environment, a new generic function is created.

If (fdefinition function-name) is an ordinary function, a macro, or a special operator, an error is signaled.

If function-name is a list, it must be of the form (setf symbol). If function-name specifies a generic function that has a different value for any of the following arguments, the generic function is modified to have the new value: :argument-precedence-order, :declare, :documentation, :method-combination.

If function-name specifies a generic function that has a different value for the :lambda-list argument, and the new value is congruent with the lambda lists of all existing methods or there are no methods, the value is changed; otherwise an error is signaled.

If function-name specifies a generic function that has a different value for the :generic-function-class argument and if the new generic function class is compatible with the old, change-class is called to change the class of the generic function; otherwise an error is signaled.

If function-name specifies a generic function that has a different value for the :method-class argument, the value is changed, but any existing methods are not changed.

Examples

None.

Affected By

Existing function binding of function-name.

Exceptional Situations

If (fdefinition function-name) is an ordinary function, a macro, or a special operator, an error of type error is signaled.

If function-name specifies a generic function that has a different value for the :lambda-list argument, and the new value is not congruent with the lambda list of any existing method, an error of type error is signaled.

If function-name specifies a generic function that has a different value for the :generic-function-class argument and if the new generic function class not is compatible with the old, an error of type error is signaled.

See Also

Notes

None.

\issue{FUNCTION-NAME:LARGE} \issue{FUNCTION-NAME:LARGE}