POE::Component(3) User Contributed Perl Documentation POE::Component(3)NAMEPOE::Component - event driven objects or subsystems
SYNOPSIS
See specific components.
DESCRIPTION
POE "components" are event-driven modules that generally encapsulate
mid- to high-level program features. For example,
POE::Component::Client::DNS performs message-based asynchronous
resolver lookups. POE::Component::Server::TCP is a basic asynchronous
network server.
The POE::Component namespace was started as place for contributors to
publish their POE-based modules without requiring coordination with the
main POE distribution. The namespace predates the -X convention,
otherwise you'd be reading about POEx instead.
As with many things in Perl, there is more than one way to implement
component interfaces. Newer components sport OO interfaces, and some
even use Moose, but older ones are solely message driven.
OBJECT ORIENTED COMPONENTS
One way to create object-oriented components is to embed a POE::Session
instance within an object. This is done by creating the session during
the object's constructor, and setting the session's alias to a
stringified version of the object reference.
package Asynchrotron;
sub new {
my $class = shift;
my $self = bless { }, $class;
POE::Session->create(
object_states => [
$self => {
_start => "_poe_start",
do_something => "_poe_do_something",
},
],
);
return $self;
}
sub _poe_start {
$_[KERNEL]->alias_set("$_[OBJECT]");
}
The alias allows object methods to pass events into the session without
having to store something about the session. The POE::Kernel call()
transfers execution from the caller session's context into the
component's session.
sub do_something {
my $self = shift;
print "Inside the caller's session right now: @_\n";
$poe_kernel->call("$self", "do_something", @_);
}
sub _poe_do_something {
my @args = @_[ARG0..$#_];
print "Inside the component's session now: @args\n";
$_[OBJECT]{count}++;
}
Both $_[HEAP] and $_[OBJECT] are visible within the component's
session. $_[HEAP] can be used for ultra-private encapsulation, while
$_[OBJECT] may be used for data visible by accessors.
sub get_count {
my $self = shift;
return $self->{count}; # $_[OBJECT]{count} above
}
Too many sessions may bog down object creation and destruction, so
avoid creating them for every object.
SEE ALSO
The SEE ALSO section in POE contains a table of contents covering the
entire POE distribution.
POE::Stage is a nascent project to formalize POE components, make
POE::Kernel more object-oriented, and provide syntactic and semantic
sugar for many common aspects of POE::Component development. It's also
easier to type. Please investigate the project. Ideas and tuits are
badly needed to help get the project off the ground.
TO DO
Document the customary (but not mandatory!) process of creating and
publishing a component.
AUTHORS & COPYRIGHTS
Each component is written and copyrighted separately.
Please see POE for more information about authors and contributors.
perl v5.14.2 2011-12-15 POE::Component(3)
