Daisuke Maki

NAME

Event::Notify - Simple Observer/Notifier

SYNOPSIS

  use Event::Notify;

  my $notify = Event::Notify->new;
  $notify->register( $observer );
  $notify->register_event( $event, $observer );
  $notify->notify( $event, @args );

DESCRIPTION

Event::Notify implements a simple Observer pattern. It's not really intended to be subclassed, or a fancy system. It just registers observers, and broadcasts events, that's it. The simplicity is that it can be embedded in a class that doesn't necessarily want to be a subclass of a notifier.

Simply create a slot for it, and delegate methods to it:

  package MyClass;
  use Event::Notify;

  sub new {
    my $class = shift;
    my $self = shift;
    $self->{notify} = Event::Notify->new;
  }

  # This interface doesn't have to be this way. Here, we're just making
  # a simple delegation mechanism 
  sub register_event { shift->{notify}->register_event(@_) }
  sub unregister_event { shift->{notify}->unregister_event(@_) }
  sub notify { shift->{notify}->notify(@_) }

Voila, you got yourself a observable module without inheritance!

METHODS

new

Creates a new instance

register($observer)

Registers a new observer. The observer must implement a notify() method.

When called, the observer's register() method is invoked, so each observer can register itself to whatever event the observer wants to subscribe to.

So your observer's register() method could do something like this:

  package MyObserver;
  sub register {
    my ($observer, $notify) = @_;
    $notify->register_event( 'event_name1', $observer );
    $notify->register_event( 'event_name2', $observer );
    $notify->register_event( 'event_name3', $observer );
    $notify->register_event( 'event_name4', $observer );
  }

Think of it as sort of an automatic initializer.

register_event($event,$observer[,\%opts])

Registers an observer $observer as observing a particular event $event The $observer can be either an object or a subroutine reference.

In case $observer is an object, the object must implement a method named notify(), or the method name specified the method parameter in the optional third parameter %opts

Calling

  $notify->register_event($event, $observer);

is the same as saying

  $notify->register_event($event, $observer, { method => 'notify' });

If the object does not implement the named method (or notify(), if you don't specify one), then it will croak

unregister_event($event,$observer)

Unregisters an observer.

notify($event,@args)

Notifies all of the observers about a particular event. @args is passed directly to the observers' notify() event

clear_observers()

Clears all observers from this object.

AUTHOR

Copyright (c) 2007 Daisuke Maki <daisuke@endeworks.jp>

LICENSE

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

See http://www.perl.com/perl/misc/Artistic.html




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