NAME

Mixin::Event::Dispatch - mixin methods for simple event/message dispatch framework

VERSION

version 0.003

SYNOPSIS

 # Add a handler then invoke it
 my $obj = Some::Class->new;
 $obj->add_handler_for_event(some_event => sub { my $self = shift; warn "had some_event: @_"; 1; });
 $obj->invoke_event(some_event => 'message here');

 # Attach event handler for all on_XXX named parameters
 package Event::User;
 sub configure {
        my $self = shift;
        my %args = @_;
        $self->add_handler_for_event(
                map { (/^on_(.*)$/) ? ($1 => $args{$_}) : () } keys %args
        );
        return $self;
 }

DESCRIPTION

Add this in as a parent to your class, and it'll provide some methods for defining event handlers ("add_event_handler") and calling them ("invoke_event").

Note that handlers should return 0 for a one-off handler, and 1 if it should be called again on the next event.

SPECIAL EVENTS

A single event has been reserved for cases where a callback dies:

• event_error - if a handler is available, this will be called instead of dying whenever any other handler dies. If an event_error handler also fails, then this error will be re-thrown. As with the other handlers, you can have more than one event_error handler.

API HISTORY

Note that 0.002 changed to use event_handlers instead of event_stack for storing the available handlers (normally only invoke_event and add_handler_for_event are expected to be called directly).

METHODS

invoke_event

Takes an event parameter, and optional additional parameters that are passed to any callbacks.

 $self->invoke_event('new_message', from => 'fred', subject => 'test message');

Returns $self if a handler was found, undef if not.

add_handler_for_event

Adds handlers to the stack for the given events.

 $self->add_handler_for_event(
        new_message     => sub { warn @_; 1 },
        login           => sub { warn @_; 1 },
        logout          => sub { warn @_; 1 },
 );

event_handlers

Accessor for the event stack itself - should return a hashref which maps event names to arrayrefs for the currently defined handlers.

clear_event_handlers

Removes all queued event handlers.

Will also be called when defining the first handler to create the initial "event_handlers" entry, should be overridden by subclass if something other than $self->{event_handlers} should be used.

WHY NOT A ROLE?

Most role systems should be able to use this class - either directly, or through a thin wrapper which adds any required boilerplate. Try Moose or Role::Tiny / Moo::Role for that.

Alternatively, you could use this as a component via Class::C3::Componentised.

SEE ALSO

There are at least a dozen similar modules already on CPAN, eventually I'll add a list of them here.

AUTHOR

Tom Molesworth <cpan@entitymodel.com>

with thanks to various helpful people on freenode #perl who suggested making "event_handlers" into an accessor (to support non-hashref objects) and who patiently tried to explain about roles.

LICENSE

Copyright Tom Molesworth 2011. Licensed under the same terms as Perl itself.

cpanm Mixin::Event::Dispatch

perl -MCPAN -e shell
install Mixin::Event::Dispatch