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 exam-
       ple of a subclassed POE::Session, in case someone wants to
       create new callback or Session semantics.

       People generally balk at the @_[KERNEL, etc.] calling con-
       vention that POE uses by default.  The author defends the
       position that this calling convention is a simple combina-
       tion 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 con-
       text.

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

       The author may be contacted by e-mail via
       rcaputo@cpan.org.

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