NAME

       Mojo::EventEmitter - Event emitter base class

SYNOPSIS

         package Cat;
         use Mojo::Base 'Mojo::EventEmitter';

         # Emit events
         sub poke {
           my $self = shift;
           $self->emit(roar => 3);
         }

         package main;

         # Subscribe to events
         my $tiger = Cat->new;
         $tiger->on(roar => sub {
           my ($tiger, $times) = @_;
           say 'RAWR!' for 1 .. $times;
         });
         $tiger->poke;

DESCRIPTION

       Mojo::EventEmitter is a simple base class for event emitting objects.

EVENTS

       Mojo::EventEmitter can emit the following events.

   error
         $e->on(error => sub {
           my ($e, $err) = @_;
           ...
         });

       This is a special event for errors, it will not be emitted directly by this class but is
       fatal if unhandled.

         $e->on(error => sub {
           my ($e, $err) = @_;
           say "This looks bad: $err";
         });

METHODS

       Mojo::EventEmitter inherits all methods from Mojo::Base and implements the following new
       ones.

   catch
         $e = $e->catch(sub {...});

       Subscribe to "error" event.

         # Longer version
         $e->on(error => sub {...});

   emit
         $e = $e->emit('foo');
         $e = $e->emit('foo', 123);

       Emit event.

   has_subscribers
         my $bool = $e->has_subscribers('foo');

       Check if event has subscribers.

   on
         my $cb = $e->on(foo => sub {...});

       Subscribe to event.

         $e->on(foo => sub {
           my ($e, @args) = @_;
           ...
         });

   once
         my $cb = $e->once(foo => sub {...});

       Subscribe to event and unsubscribe again after it has been emitted once.

         $e->once(foo => sub {
           my ($e, @args) = @_;
           ...
         });

   subscribers
         my $subscribers = $e->subscribers('foo');

       All subscribers for event.

         # Unsubscribe last subscriber
         $e->unsubscribe(foo => $e->subscribers('foo')->[-1]);

         # Change order of subscribers
         @{$e->subscribers('foo')} = reverse @{$e->subscribers('foo')};

   unsubscribe
         $e = $e->unsubscribe('foo');
         $e = $e->unsubscribe(foo => $cb);

       Unsubscribe from event.

DEBUGGING

       You can set the "MOJO_EVENTEMITTER_DEBUG" environment variable to get some advanced
       diagnostics information printed to "STDERR".

         MOJO_EVENTEMITTER_DEBUG=1

SEE ALSO

       Mojolicious, Mojolicious::Guides, <http://mojolicio.us>.