NAME
    Callback - object interface for function callbacks

SYNOPSIS
            use Callback;

            my $callback = new Callback (\&myfunc, @myargs);
            my $callback = new Callback ($myobj, $mymethod, @myargs);

            $callback->call(@some_more_args);

DESCRIPTION
    Callback provides a simple interface for function callbacks. It would be
    possible to provide nearly all of the functionality using inline code
    references. Callback was written before inline code references were
    added to perl.

    What callback does provide is a simple interface for common situation:
    passing around a function.

    When a callback is constructed, a base set of arguments can be provided.
    These function arguments will preceed any arguments added at the time
    the call is made.

    There are two forms for the callback constructor, depending on whether
    the call is a pure functional call or a method call. The rule is that if
    the first argument is an object, then the second argument is a method
    name to be called on that object.

TRACING
            use Callback qw(@callbackTrace);

    If you're writing a debugging routine that provides a stack-dump (for
    example, Carp::confess) it is useful to know where a callback was
    registered.

            my $ct = 0;
            while (($package, $file, $line, $subname, $hasargs, $wantarray) = caller($i++)) {
                ...

                if ($subname eq 'Callback::call') {
                    print "callback registered $Callback::callbackTrace[$ct]\n";
                    $ct++;
                }
            }

    Without such code, it becomes very hard to know what's going on.

COPYRIGHT
    Copyright (C) 1994, 2000, David Muir Sharnoff. All rights reserved.
    License hearby granted for anyone to use this module at their own risk.
    Please feed useful changes back to muir@idiom.com.