/ 
POE-Session-MessageBased-0.111
River stage one • 1 direct dependent • 1 total dependent
/ POE::Session::MessageBased

NAME

POE::Session::MessageBased - a message-based (not @_ based) POE::Session

SYNOPSIS

use POE::Kernel;
use POE::Session::MessageBased;

POE::Session::MessageBased->create(
	inline_states => {
		_start => sub {
			my $message = shift;
			print "Started.\n";
			$message->kernel->yield( count => 2 );
		},
		count => sub {
			my ($message, $count) = @_;
			print "Counted to $count.\n";
			if ($count < 10) {
				$message->kernel->yield( count => ++$count );
			}
		},
		_stop => sub {
			print "Stopped.\n";
		}
	},
);

POE::Kernel->run();

DESCRIPTION

POE::Session::MessageBased exists mainly to replace @_[KERNEL, etc.] with message objects that encapsulate various aspects of each event. It also exists as an example of a subclassed POE::Session, in case someone wants to create new callback or Session semantics.

People generally balk at the @_[KERNEL, etc.] calling convention that POE uses by default. The author defends the position that this calling convention is a simple combination of common Perl features. Interested people can read http://poe.perl.org/?POE_FAQ/calling_convention for a more detailed account.

Anyway, POE::Session::MessageBased subclasses POE::Session and works almost identically to it. The major change is the way event handlers (states) are called.

Inline (coderef) handlers gather their parameters like this.

my ($message, @args) = @_;

Package and object-oriented handlers receive an additional parameter representing the package or object. This is part of the common calling convention that Perl uses.

my ($package, $message, @args) = @_;  # Package states.
my ($self, $message, @args) = @_;     # Object states.

The $message parameter is an instance of POE::Session::Message, which is not documented elsewhere. POE::Session::Message encapsulates every POE parameter and provides accessors for them.

POE::Session             POE::Session::MessageBased
------------------------ -----------------------------------
$_[OBJECT]               $package, or $self
$_[SESSION]              $message->session
$_[KERNEL]               $message->kernel
$_[HEAP]                 $message->heap
$_[STATE]                $message->state
$_[SENDER]               $message->sender
$_[CALLER_FILE]          $message->caller_file
$_[CALLER_LINE]          $message->caller_line
@_[ARG0..$#_]            $message->args (in list context)

You do not need to use POE::Session::Message yourself. It is included in POE::Session::MessageBased itself.

BUGS

$message->args() always returns a list: @_[ARG0..$#_]. It would be nice to return a list reference in scalar context.

BUG TRACKER

https://rt.cpan.org/Dist/Display.html?Status=Active&Queue=POE-Session-MessageBased

REPOSITORY

http://github.com/rcaputo/poe-session-messagebased http://gitorious.org/poe-session-messagebased

OTHER RESOURCES

http://search.cpan.org/dist/POE-Session-MessageBased/

AUTHOR & LICENSE

POE::Session::MessageBased is Copyright 2002-2010 by Rocco Caputo. All rights are reserved. POE::Session::MessageBased is free software; you may redistribute it and/or modify it under the same terms as Perl itself.