CLHS: Accessor FIND-CLASS

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Accessor FIND-CLASS

Syntax:

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.

Description:

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.

Examples: None.

Affected By: None.

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)

Notes: None.

The following X3J13 cleanup issues, not part of the specification, apply to this section:

- SETF-FIND-CLASS:ALLOW-NIL
- MACRO-ENVIRONMENT-EXTENT:DYNAMIC

Copyright 1996-2005, LispWorks Ltd. All rights reserved.