NAME

POE::API::Hooks - Implement lightweight hooks into POE

SYNOPSIS

  use POE;
  use POE::API::Hooks;

  POE::API::Hooks->add(
      before_event_dispatch  => \&do_something,
      after_event_dispatch   => \&do_something,
      before_session_create  => \&do_something,
      after_session_create   => \&do_something,
      before_event_enqueue   => \&do_something,
      after_event_enqueue    => \&do_something,
  );

  # ... carry on with life as normal ...

DISCUSSION

This module adds lightweight hooks into the inner workings of POE. Currently, one can add hooks into POE that get called before/after an event is dispatched, before/after a Session is created, and/or before/after an event is enqueued. These callbacks receive the exact same argument list as their Kernel/Session counterpart. For event dispatch related callbacks, see "_dispatch_event" and "_data_ev_enqueue" in POE::Kernel. For session related callbacks, see "create" in POE::Session.

WARNING

This interface is designed for advanced users. Wrapping any of the available POE internals is a potentially dangerous operation. Please read the POE documentation and source code carefully before attempting an override of this nature.

METHODS

add

  POE::API::Hooks->add(
      before_event_dispatch  => \&do_something,
      after_event_dispatch   => \&do_something,

      before_session_create  => \&do_something,
      after_session_create   => \&do_something,

      before_event_enqueue   => \&do_something,
      after_event_enqueue    => \&do_something,
  );

"add" is the only public method of this class. The method installs the requested hooks. The list of options above contains all possible hooks. No hook is required so the user may set only one hook if they desire.

The callback provided for each hook will be called, obviously, when that state occurs. "before_event_dispatch" will be called just before event dispatch, for instance. These callbacks are passed whatever arguments are provided to the wrapped subroutine. For instance, if a "before_session_create" callback is registered and a user calls "POE::Session->create('POE')", the registered callback will receive "('POE::Session', 'POE')" in @_.

BUGS

When "$_[KERNEL]->call($_[SESSION], "event")" is used, _event_dispatch is bypassed. This is an optimization, not a bug, but it will cause the event_dispatch hook to be bypassed under this condition. Someone relying on the event_dispatch hook may call this a bug.

AUTHOR

Matt Cashner (sungo@pobox.com)

LICENSE

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
Neither the name of Matt Cashner nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.