| |
ANSI Common Lisp  7 Objects 7.7 Dictionary of Objects
| 7.7.34 find-method |
Standard Generic Function |
- Syntax:
-
find-method
generic-function method-qualifiers specializers &optional errorp
 method
- Method Signatures:
-
find-method
(generic-function standard-generic-function)
method-qualifiers specializers &optional errorp
- Arguments and Values:
-
generic-function - a generic function.
method-qualifiers - a list.
specializers - a list.
errorp - a generalized boolean.
The default is true.
method - a method object, or nil.
- Description:
-
The generic function find-method takes a generic function
and returns the method object that agrees on qualifiers
and parameter specializers with the method-qualifiers and
specializers arguments of find-method.
Method-qualifiers contains the
method qualifiers for the method.
The order of the method qualifiers
is significant.
For a definition of agreement in this context,
see Section 7.6.3 Agreement on Parameter Specializers and Qualifiers.
The specializers argument contains the parameter
specializers for the method. It must correspond in length to
the number of required arguments of the generic function, or
an error is signaled. This means that to obtain the
default method on a given generic-function,
a list whose elements are the class t must be given.
If there is no such method and errorp is true,
find-method signals an error.
If there is no such method and errorp is false,
find-method returns nil.
- Examples:
-
(defmethod some-operation ((a integer) (b float)) (list a b))
#<STANDARD-METHOD SOME-OPERATION (INTEGER FLOAT) 26723357>
(find-method #'some-operation '() (mapcar #'find-class '(integer float)))
#<STANDARD-METHOD SOME-OPERATION (INTEGER FLOAT) 26723357>
(find-method #'some-operation '() (mapcar #'find-class '(integer integer)))
 Error: No matching method
(find-method #'some-operation '() (mapcar #'find-class '(integer integer)) nil)
NIL
- Affected By:
-
add-method,
defclass,
defgeneric,
defmethod
- Exceptional Situations:
-
If the specializers argument does not correspond in length to
the number of required arguments of the generic-function, an
an error of type error is signaled.
If there is no such method and errorp is true,
find-method signals an error of type error.
- See Also:
-
Section 7.6.3 Agreement on Parameter Specializers and Qualifiers
- Allegro CL Implementation Details:
-
None.
|
