Callback(3) User Contributed Perl Documentation Callback(3)NAMECallback - object interface for function callbacks
SYNOPSIS
use Callback;
my $callback = new Callback (\&myfunc, @myargs);
my $callback = new Callback ($myobj, $mymethod, @myargs);
my $callback = new Callback ($old_callback, @myargs);
$callback->call(@some_more_args);
DESCRIPTIONCallback provides a standard interface to register callbacks. Those
callbacks can be either purely functional (i.e. a function call with
arguments) or object-oriented (a method call on an object).
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. Method resolution happens at
the time the Callback object is built: an error will be raised if it
cannot be found.
Callback objects built for object-oriented calls also have the property
of being serializable via Storable. Purely functional callabacks
cannot be serialized because CODE references are not supported by
Storable.
Callback objects can be created from existing Callback objects. Any
arguments will be appended onto the original list of arguments.
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, 2002 David Muir Sharnoff. All rights
reserved. This module may be licensed on the same terms as Perl
itself.
AUTHORS
David Muir Sharnoff <muir@idiom.com> and Raphael Manfredi
<Raphael_Manfredi@pobox.com>
SEE ALSOStorable(3).
perl v5.14.0 2007-03-05 Callback(3)
