NAME¶
POE::Component::Syndicator - A POE component base class which implements the
Observer pattern
SYNOPSIS¶
package POE::Component::IRC;
use strict;
use warnings;
use POE;
use base 'POE::Component::Syndicator';
# our constructor
sub spawn {
my ($package, %args) = @_;
# process arguments...
my $self = bless \%args, $package;
# set up our plugin system and POE session
$self->_syndicator_init(
prefix => 'irc_',
reg_prefix => 'PCI_',
types => [SERVER => 'S', USER => 'U'],
object_states => [qw(
syndicator_started
shutdown
)],
);
return $self;
}
sub syndicator_started {
my ($kernel, $self) = @_[KERNEL, OBJECT];
# connect to a server, etc...
}
# plugin handler for SERVER event 'hlagh'
sub S_hlagh {
# ...
}
sub shutdown {
my ($kernel, $self) = @_[KERNEL, OBJECT];
# disconnect from a server, etc...
# shut down the syndicator
$self->_syndicator_destroy();
}
DESCRIPTION¶
POE::Component::Syndicator is a base class for POE components which need to
handle a persistent resource (e.g. a connection to an IRC server) for one or
more sessions in an extendable way.
This module (as well as Object::Pluggable, which this module inherits from) was
born out of POE::Component::IRC, the guts of which quickly spread to other POE
components. Now they can all inherit from this module instead.
The component provides an event queue, which can be managed with the methods
documented below. It handles delivery of events to the object itself, all
interested plugins, and all interested sessions.
Component lifetime¶
You start by calling "_syndicator_init", which will create a POE
session with your object as its heap, and a few event handlers installed. The
events described in "Local events" delimit the start and end of the
session's lifetime. In between those, interested plugins and sessions will
receive various events, usually starting with
"syndicator_registered". In this phase, your subclass and plugins
can call the methods and send the events documented below. When the component
has been shut down, sessions (but not plugins) will receive a
"syndicator_shutdown" event. After this, the component will become
unusable.
A note on events¶
In this document, an
event (unless explicitly referred to as a
POE
event) is defined as a message originating from
POE::Component::Syndicator, delivered to plugins (and the subclass) via plugin
methods and to registered sessions as POE events.
Interested sessions are considered consumers only, so they always receive copies
of event arguments, whereas interested plugins and subclasses receive scalar
references to them. This allows them to alter, add, or remove event arguments
before sessions (or even other plugins) receive them. For more information
about plugins, see Object::Pluggable's documentation. A subclass does not have
to register for plugin events.
Two event types are supported: SERVER and USER, though their names can be
overridden (see "_syndicator_init").
SERVER events
These represent data received from the network or some other outside resource
(usually a server, hence the default name).
SERVER events are generated by the "send_event*" methods. These events
are delivered to the subclass and plugins (method "S_foo") and
interested sessions (event "syndicator_foo").
USER events
These represent commands about to be sent to a server or some other resource.
USER events are generated by "send_user_event". In addition, all POE
events sent to this component's session (e.g. with "yield") which do
not have a handler will generate corresponding USER events. USER events are
considered more private, so they are only delivered to the subclass and
plugins, not to sessions.
PRIVATE METHODS¶
The following methods should only be called by a subclass.
"_syndicator_init"¶
You should call this in your constructor. It initializes Object::Pluggable,
creates the Syndicator's POE session, and calls the
"syndicator_started" POE events. It takes the following arguments:
'prefix', a prefix for all your event names, when sent to interested
sessions. If you don't supply this, Object::Pluggable's default (
'pluggable') will be used.
'reg_prefix', the prefix for the
"register()"/"unregister()" plugin methods If you don't
supply this, Object::Pluggable's default (
'plugin_') will be used.
'debug', a boolean, if true, will cause a warning to be printed every
time a plugin event handler raises an exception.
'types', a 2-element arrayref of the types of events that your component
will support, or a 4-element (2 pairs) arrayref where the event types are keys
and their abbrevations (used as plugin event method prefixes) are values (see
"A note on events" and Object::Pluggable for more information). The
two event types are fundamentally different, so make sure you supply them in
the right order. If you don't provide this argument, "[ SERVER => 'S',
USER => 'U' ]" will be used.
'register_signal', the name of the register signal (see
"SIGNALS"). Defaults to
'SYNDICATOR_REGISTER'.
'shutdown_signal', the name of the shutdown signal (see
"SIGNALS"). Defaults to
'SYNDICATOR_SHUTDOWN'.
'object_states' an arrayref of additional object states to add to the POE
session. Same as the 'object_states' argument to POE::Session's
"create" method. You'll want to add a handler for at least the
"syndicator_started" event.
'options', a hash of options for POE::Session's constructor.
If you call "_syndicator_init" from inside another POE session, the
component will automatically register that session as wanting all events. That
session will first receive a "syndicator_registered" event.
"_syndicator_destroy"¶
Call this method when you want Syndicator to clean up (delete all plugins, etc)
and make sure it won't keep the POE session alive after all remaining events
have been processed. A "syndicator_shutdown" event (or similar,
depending on the prefix you chose) will be generated. Any argument passed to
"_syndicator_destroy" will be passed along with that event.
Note: this method will clear all alarms for the POE session.
PUBLIC METHODS¶
"session_id"¶
Returns the component's POE session id.
"session_alias"¶
Returns the component's POE session alias.
"yield"¶
This method provides an alternative, object-based means of posting events to the
component. First argument is the event to post, following arguments are sent
as arguments to the resultant post.
"call"¶
This method provides an alternative, object-based means of calling events to the
component. First argument is the event to call, following arguments are sent
as arguments to the resultant call.
"send_event"¶
Adds a new SERVER event onto the end of the queue. The event will be processed
after other pending events, if any. First argument is an event name, the rest
are the event arguments.
$component->send_event('irc_public, 'foo!bar@baz.com', ['#mychan'], 'message');
"send_event_next"¶
Adds a new SERVER event to the start of the queue. The event will be the next
one to be processed. First argument is an event name, the rest are the event
arguments.
"send_event_now"¶
Sends a new SERVER event immediately. Execution of the current POE event will be
suspended (i.e. this call will block) until the new event has been processed
by the component class and all plugins. First argument is an event name, the
rest are the event arguments.
"send_user_event"¶
Sends a new USER event immediately. You should call this before every command
you send to your remote server/resource. Only the subclass and plugins will
see this event. Takes two arguments, an event name and an arrayref of
arguments. Returns one of the "EAT" constants listed in
Object::Pluggable::Constants. After this method returns, the arrayref's
contents may have been modified by the subclass or plugins.
$component->send_user_event('PRIVMSG', '#mychan', 'message');
"delay"¶
This method provides a way of posting delayed events to the component. The first
argument is an arrayref consisting of the delayed command to post and any
command arguments. The second argument is the time in seconds that one wishes
to delay the command being posted.
my $alarm_id = $component->delay(['mode', $channel, '+o', $dude], 60);
"delay_remove"¶
This method removes a previously scheduled delayed event from the component.
Takes one argument, the "alarm_id" that was returned by a
"delay" method call. Returns an arrayref of arguments to the event
that was originally requested to be delayed.
my $arrayref = $component->delay_remove($alarm_id);
EVENTS¶
Local events¶
The component will send the following POE events to its session.
"syndicator_started"
Called after the session has been started (like "_start" in
POE::Kernel. This is where you should do your POE-related setup work such as
adding new event handlers to the session.
"syndicator_stopped"
Called right before the session is about to die (like "_stop" in
POE::Kernel).
Other POE sessions can send the following POE events to the Syndicator's
session.
"register"
Takes any amount of arguments: a list of event names that your session wants to
listen for, minus the prefix (specified in "_syndicator_init" in
"syndicator_init").
$kernel->post('my syndicator', 'register', qw(join part quit kick));
Registering for the special event
'all' will cause it to send all events
to your session. Calling it with no event names is equivalent to calling it
with
'all' as an argumente.
Registering will generate a "syndicator_registered" event that your
session can trap.
Registering with multiple component sessions can be tricky, especially if one
wants to marry up sessions/objects, etc. Check the SIGNALS section for an
alternative method of registering with multiple components.
"unregister"
Takes any amount of arguments: a list of event names which you
don't want
to receive. If you've previously done a "register" for a particular
event which you no longer care about, this event will tell the component to
stop sending them to you. (If you haven't, it just ignores you. No big deal.)
Calling it with no event names is equivalent to calling it with
'all'
as an argument.
If you have registered for the special event
'all', attempting to
unregister individual events will not work. This is a 'feature'.
"shutdown"
By default, POE::Component::Syndicator sessions never go away. You can send its
session a "shutdown" event manually to make it delete itself.
Terminating multiple Syndicators can be tricky. Check the "SIGNALS"
section for a method of doing that.
"_default"
Any POE events sent to the Syndicator's session which do not have a handler will
go to the Syndicator's "_default" handler, will generate "USER
events" of the same name. If you install your own "_default"
handler, make sure you do the same thing before you handle an event:
use Object::Pluggable::Constants 'PLUGIN_EAT_ALL';
$poe_kernel->state('_default', $self, '__default');
sub __default {
my ($self, $event, $args) = @_[OBJECT, ARG0, ARG1];
# do nothing if a plugin eats the event
return if $self->send_user_event($event, [@$args]) == PLUGIN_EAT_ALL;
# handle the event
# ...
}
Note that the handler for the "_default" event must be named something
other than '_default', because that name is reserved for the plugin-type
default handler (see the Object::Pluggable docs).
Output events¶
The Syndicator will send the following events at various times. The
'syndicator_' prefix in these event names can be customized with a
'prefix' argument to "_syndicator_init" in
"_syndicator_init".
"syndicator_registered"
Sent once to the requesting session on registration (see "register").
"ARG0" is a reference to the component's object.
"syndicator_shutdown"
Sent to all interested sessions when the component has been shut down. See
"_syndicator_destroy".
"syndicator_delay_set"
Sent to the subclass, plugins, and all interested sessions on a successful
addition of a delayed event using the "delay" method.
"ARG0" will be the alarm_id which can be used later with
"delay_remove". Subsequent parameters are the arguments that were
passed to "delay".
"syndicator_delay_removed"
Sent to the subclass, plugins, and all interested sessions when a delayed event
is successfully removed. "ARG0" will be the alarm_id that was
removed. Subsequent parameters are the arguments that were passed to
"delay".
All other events
All other events sent by the Syndicator are USER events (generated with
"send_user_event") and SERVER events (generated with
"send_event*") which will be delivered normally. Your subclass and
plugins are responsible for generating them.
SIGNALS¶
The component will handle a number of custom signals that you may send using
POE::Kernel's "signal" method. They allow any session to communicate
with every instance of the component in certain ways without having references
to their objects or knowing about their sessions. The names of these signals
can be customized with "_syndicator_init".
"SYNDICATOR_REGISTER"¶
Registers for an event with the component. See "register".
"SYNDICATOR_SHUTDOWN"¶
Causes a 'shutdown' event to be sent to your session. Any arguments to the
signal will be passed along to the event. That's where you should clean up and
call "_syndicator_destroy".
AUTHOR¶
Hinrik Oern Sigurd`sson, hinrik.sig@gmail.com, Chris "BinGOs" Williams
chris@bingosnet.co.uk, Apocalypse apocal@cpan.org, and probably others.
LICENSE AND COPYRIGHT¶
Copyright 2011 Hinrik Oern Sigurd`sson
This program is free software, you can redistribute it and/or modify it under
the same terms as Perl itself.