getClass               package:methods               R Documentation

Get Class Definition

Description:

     Get the definition of a class.

Usage:

     getClass(Class, .Force = FALSE)
     getClassDef(Class, where=-1)

Arguments:

   Class: the character-string name of the class.

  .Force: if `TRUE', return `NULL' if the class is undefined;
          otherwise, an undefined class results in an error. 

   where: 

     { where to search for the definition; by default, anywhere on the
     current search list.}

Details:

     A call to `getClass' returns the complete definition of the class
     supplied as a string, including all slots, etc. in classes that
     this class extends. A call to `getClassDef' returns  the
     definition of the class from that database, unadorned.  It's
     usually `getClass' you want.

     The statement that `getClass' fails if the class is undefined is
     not quite true at the moment.  A few special vector types and
     informally defined classes are allowed, and `getClass' returns
     `NULL' for these. But don't count on it; eventually these holes in
     the class system should be plugged.

     In any case, if you really want to know whether a class is
     formally defined, call `isClass'.

Value:

     The object defining the class.  This is an object of class
     `"classRepEnvironment"'.  However, do not deal with the contents
     of the object directly unless you are very sure you know what
     you're doing.  Even then, it is nearly always better practice to
     use functions such as `setClass' and `setIs'. Messing up a class
     object will cause great confusion.

Author(s):

     John Chambers

References:

     The web page <URL: http://www.omegahat.org/RSMethods/index.html>
     is the primary documentation.

     The functions in this package emulate the facility for classes and
     methods described in Programming with Data, (John M. Chambers,
     Springer, 1998).  See this book for further details and examples.

See Also:

     Classes, `setClass', `isClass'.

Examples:

     getClass("numeric") ## a built in class

