Mojo::EventEmitter(3)

NAME
Mojo::EventEmitter - Event emitter base class

SYNOPSIS
  package Cat;
  use Mojo::Base 'Mojo::EventEmitter', -signatures;

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

  package main;

  # Subscribe to events
  my $tiger = Cat->new;
  $tiger->on(roar => sub ($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
  $e->on(error => sub ($e, $err) {...});

This is a special event for errors, it will not be emitted directly by this class, but is fatal if unhandled. Subclasses may choose to emit it, but are not required to do so.

  $e->on(error => sub ($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.

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

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

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

  $e->once(foo => sub ($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, <https://mojolicious.org>.