NAME

Class::Trigger - Mixin to add / call inheritable triggers

SYNOPSIS

package Foo;
use Class::Trigger;

sub foo {
    my $self = shift;
    $self->call_trigger('before_foo');
    $self->do_foo;
    $self->call_trigger('after_foo');
}

package main;
Foo->add_trigger(before_foo => \&sub1);
Foo->add_trigger(after_foo => \&sub2);

my $foo = Foo->new;
$foo->foo;			# then sub1, sub2 called

# triggers are inheritable
package Bar;
use base qw(Foo);

Bar->add_trigger(before_foo => \&sub);

# triggers can be object based
$foo->add_hook(after_foo => \&sub3);
$foo->foo;			# sub3 would appply only to this object

DESCRIPTION

Class::Trigger is a mixin class to add / call triggers (or hooks) that get called at some points you specify.

METHODS

By using this module, your class is capable of following two methods.

add_trigger

Foo->add_trigger($triggerpoint => $sub);
$foo->add_trigger($triggerpoint => $sub);

Adds triggers for trigger point. You can have any number of triggers for each point. Each coderef will be passed a copy of the object, and return values will be ignored.

If add_trigger is called as object method, whole trigger table will be copied onto the object. Then the object should be implemented as hash.

my $foo = Foo->new;

# this trigger ($sub_foo) would apply only to $foo object
$foo->add_trigger($triggerpoint => $sub_foo);
$foo->foo;

# And not to another $bar object
my $bar = Foo->new;
$bar->foo;

call_trigger

$foo->call_trigger($triggerpoint);

Calls triggers for trigger point, which were added via add_trigger method. Each triggers will be passed a copy of the object.

TRIGGER POINTS

By default you can make any number of trigger points, but if you want to declare names of trigger points explicitly, you can do it via import.

package Foo;
use Class::Trigger qw(foo bar baz);

package main;
Foo->add_trigger(foo  => \&sub1); # okay
Foo->add_trigger(hoge => \&sub2); # exception

AUTHOR

Original idea by Tony Bowden <tony@kasei.com> in Class::DBI.

Code by Tatsuhiko Miyagawa <miyagawa@bulknews.net>.

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

SEE ALSO

Class::Data::Inheritable