genericFunction-class        package:methods        R Documentation

Generic Function Objects

Description:

     Generic functions (objects from or extending class
     'genericFunction') are extended function objects, containing
     information used in creating and dispatching methods for this
     function.  They also identify the package associated with the
     function and its methods.

Objects from the Class:

     Generic functions are created and assigned by 'setGeneric' or
     'setGroupGeneric' and, indirectly, by 'setMethod'.

     As you might expect 'setGeneric' and 'setGroupGeneric' create
     objects of class '"genericFunction"' and '"groupGenericFunction"'
     respectively.

Slots:


     '.Data': Object of class '"function"', the function definition of
          the generic, usually created automatically as a call to
          'standardGeneric'. 

     'generic': Object of class '"character"', the name of the generic
          function. 

     'package': Object of class '"character"', the name of the package
          to which the function definition belongs (and _not_
          necessarily where the generic function is stored). If the
          package is not specified explicitly in the call to
          'setGeneric', it is usually the package on which the
          corresponding non-generic function exists. 

     'group': Object of class '"list"', the group or groups to which
          this generic function belongs.  Empty by default. 

     'valueClass': Object of class '"character"'; if not an empty
          character vector, identifies one or more classes.  It is
          asserted that all methods for this function return objects
          from these class (or from classes that extend them). 

     'signature': Object of class '"character"', the vector of formal
          argument names that can appear in the signature of methods
          for this generic function.  By default, it is all the formal
          arguments, except for ....  Order matters for efficiency: 
          the most commonly used arguments in specifying methods should
          come first. 

     'default': Object of class '"OptionalMethods"', the default method
          for this function.  Generated automatically and used to
          initialize method dispatch. 

     'skeleton': Object of class '"call"', a slot used internally in
          method dispatch.  Don't expect to use it directly.

Extends:

     Class '"function"', from data part.
      Class '"OptionalMethods"', by class '"function"'.
      Class '"PossibleMethod"', by class '"function"'.

Methods:

     Generic function objects are used in the creation and dispatch of
     formal methods; information from the object is used to create
     methods list objects and to merge or update the existing methods
     for this generic.

