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With the defgeneric/defmethod constructs, new generic functions may be written

directly in CLIPS. Generic functions are similar to deffunctions because

they can be used to define new procedural code directly in CLIPS, and they can

be called like any other function. However, generic functions are much more

powerful because they can do different things depending on the types

(or classes) and number of their arguments. For example, a '+' operator could

be defined which performs concatenation for strings but still performs

arithmetic addition for numbers. Generic functions are comprised of

multiple components called methods, where each method handles different

cases of arguments for the generic function. A generic function which has

more than one method is said to be overloaded.

A generic function is comprised of a header (similar to a forward declaration)

and zero or more methods. A generic function header can either be explicitly

declared by the user or implicitly declared by the definition of at least one

method. The defgeneric construct is used to specify the generic function header,

and the defmethod construct is used for each of the generic function's methods.

The syntax of the defgeneric/defmethod constructs is:

(defgeneric <name> [<comment>])

(defmethod <name> [<index>] [<comment>]
    (<parameter-restriction>* [<wildcard-parameter>])

<parameter-restriction> ::= <single-field-variable> |
                            (<single-field-variable> <type>* [<query>])

<wildcard-parameter>    ::= <multifield-variable>

<type>                  ::= <class-name>

<query>                 ::= <global-variable> | <function-call>
clips/clip5foj.txt · Last modified: 2010/01/04 20:46 (external edit)
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