ToC DocOverview CGDoc RelNotes Index PermutedIndex
Allegro CL
Home Previous Up Next Table of Contents Index
  ANSI Common Lisp   7 Objects   7.7 Dictionary of Objects

7.7.28 find-class Accessor

find-class symbol &optional errorp environment    class

(setf (find-class symbol &optional errorp environment) new-class)

Arguments and Values:
symbol - a symbol.

errorp - a generalized boolean. The default is true.

environment -- same as the &environment argument to macro expansion functions and is used to distinguish between compile-time and run-time environments. The &environment argument has dynamic extent; the consequences are undefined if the &environment argument is referred to outside the dynamic extent of the macro expansion function.

class - a class object, or nil.

Returns the class object named by the symbol in the environment. If there is no such class, nil is returned if errorp is false; otherwise, if errorp is true, an error is signaled.

The class associated with a particular symbol can be changed by using setf with find-class; or, if the new class given to setf is nil, the class association is removed (but the class object itself is not affected). The results are undefined if the user attempts to change or remove the class associated with a symbol that is defined as a type specifier in this standard. See Section 4.3.7 Integrating Types and Classes.

When using setf of find-class, any errorp argument is evaluated for effect, but any values it returns are ignored; the errorp parameter is permitted primarily so that the environment parameter can be used.

The environment might be used to distinguish between a compile-time and a run-time environment.

Exceptional Situations:
If there is no such class and errorp is true, find-class signals an error of type error.

See Also:
defmacro, Section 4.3.7 Integrating Types and Classes

Allegro CL Implementation Details:

Home Previous Up Next Table of Contents Index
© Franz Inc. All Rights Reserved - File last updated 2022-07-25