Robert 'phaylon' Sedlacek
and 1 contributors




  package POE::MyComponent;

  #  use as base
  use base qw/ POE::Component::Basement /;
  #  where the initializations happen (see Class::Std)
  sub BUILD { ... }
  #  see also Class::Std and Class::Data::Inheritable also 
  #  for accessor creation etc.
  #  define states
  sub state_one   : State( :inline<_start> ) { ... }
  sub state_two   : State( :object<foo> ) { ... }
  sub state_three : State( :package<bar> ) { ... }
  #  combined
  sub state_multi : State( :inline<foobar> :package<snafoo> ) { ... }

  #  chained events
  sub first : State( :object<foo> :chained<bar> ) { ... }
  sub second : State( :object<bar> ) { ... }

  #  calling in a row
  sub first : State( :object<foo> :next<bar> ) { ... }
  sub second : State( :object<bar> ) { ... }
  #  usage
  my $comp = POE::MyComponent->new ({
      #  single alias or array reference for multiple
      aliases => [qw/ mycomp shub_niggurath /],

      ...  #  your specific init_arg's.


Provides Class::Std and base POE component functionality. This module is still kinda experimental.


Setting session_class

Determines on which class the session should be built on. To use, for instance, POE::Session::MessageBased, set the option like this:

  MyComponent->session_class( 'POE::Session::MessageBased' );

The default is POE::Session.

Option aliases

Can be a single value to be set as alias, or an array reference. If the latter, POE::Kernel's alias_set is called for each of it's elements. This must be supplied as argument to the new method. See SYNOPSIS for examples.


This module just uses the attribute State and delegates all other attribute handling to Class::Std. Parameters can multiple, separated by spaces. They look like those of Class::Std to be coherent. As an example:

  sub start_event : State( :inline<_start> ) {

This would create an inline_state for our session, named _start.

inline, package and object

Create inline_states, package_states or object_states in your session. Multiple specifications of these parameters cause multiple events to be defined. Have a look at POE for more information.


  sub first : State( :inline<_start> :chained<end> ) { 
      print "Called first.\n";
      return 23;
  sub end : State( :inline<end> ) {
      my $last_return = $_[ARG0];
      print "Called second. First returned $last_return\n";

Specifies with which event the current state should be chained. If you use chained, the given event will be triggered after the sub has completed. It's return values will be passed to the chained event.


  #  the event gets triggered
  POE::Kernel->yield( foo => 333 );

  sub first : State( :inline<foo> :next<bar> ) {
      my ( $nr ) = $_[ARG0];
  sub second : State( :inline<bar> ) {
      my ( $nr ) = $_[ARG0];

An event that was specified with next is triggered right after completion of the current subroutine. The next event gets the same parameters as the current.


  sub first : State( :inline<foo> :error<error_occured> ) {
      die "in the name of Cthulhu";

  sub second : State( :inline<error_occured> ) {
      my $error = $_[ARG0];
      print 'An Error has occured: ' . $error;

If an error handling state is defined, PCB will build an eval block around the subroutine call and emit the event specified with error. First argument is the error message.


Currently, you can overload the called methods in package and object states. Though you have to do this without specifying a new State() attribute. The new method has the same attributes as the overriden. The latter can also be called with NEXT. This basic way works like:

  #  the original
  package Original;
  sub whatever : State( :package<_start> ) { ... }
  #  the new one
  package NewOne;
  use base qw/ Original /;
  sub whatever { ... }

But for information, I'm planning the possibility to override specific events.


Methods starting with an underline (_) is thought as internal to POE::Component::Basement and should therefore not be called directly.


  ( $name, $param ) = _parse_attribute( $attribute )

Takes an attribute and tries to split it into name and parameters. Returns undef if nothing usable found.


Constructor. See SYNOPSIS for usage. This overrides the new method provided by Class::Std.


This is an internal sub that's responsible for building your state-map, as it is called on specification of an attribute. See perldoc's attributes for more information about this subject. This is an internal function, do not call directly.


  $code = _create_modified_state( \&coderef, \%params );

Does the wrapping for the more enhanced attributes. Internal, do not call.


  void register_states( $class, $coderef, { state_name => 'type' } );

Registers states corresponding to a specific code reference. Accepted state names are inline, package and object. Internal, do not call.


  @classes_in_family = _flatten_inheritance( $rootclass )

Returns an array with names of classes used in the specified $rootclass' inheritance tree. This is internal, do not call.


  \%struct = $comp->get_states()

Returns a structure containing the defined inline, package and object states ready to use for POE::Sessions constructor. Internal and restricted, do not call.


  $subname = _get_symbol_name( $class, $coderef );

Searches for a code reference in the symbol table of a class and returns the sub's name if found. Otherwise undef. Do not call.


  %parameters = _parse_parameters( $parameter_string )

This function looks for parameters formed like :name<value> and returns them in ( name => value, .. ) like pairs. Dies on malformed or unknown parameters. Internal method, do not call.


POE, Class::Std, Class::Data::Inheritable


POE, Class::Std, Carp, Scalar::Util, NEXT, Sub::Installer, Class::Data::Inheritable


Robert Sedlacek <>


You can copy and/or modify this module under the same terms as perl itself.