CL Enumerations: Standard Generic Function PREVIOUS
 

Generic function PREVIOUS

Package:

CL.EXTENSIONS.ENUMERATIONS

Syntax:

  previous enumeration &optional default
  => object
  

Arguments and Values:

enumeration---an enumeration instance

default---an object

object---an object

Description:

The generic function PREVIOUS returns the "previous" object in the enumeration enumeration if there is one, as determined by calling HAS-PREVIOUS-P. If HAS-PREVIOUS-P returns NIL and default is supplied, then default is returned. Otherwise the condition NO-SUCH-ELEMENT is signaled.

Affected By:

None.

Exceptional Situations:

PREVIOUS signals the NO-SUCH-ELEMENT condition when there are no more elements in the enumeration and no default was supplied.

See Also:

ENUMERATION class, HAS-NEXT-P, CURRENT, PREVIOUS, HAS-PREVIOUS-P, NO-SUCH-ELEMENT.

Notes:

None.