NAME

MooseX::Observer::Role::Observer - Tags a Class as being an Observer

VERSION

version 0.004

SYNOPSIS

############################################################################
package Counter;

use Moose;

has count => (
    traits  => ['Counter'],
    is      => 'rw',
    isa     => 'Int',
    default => 0,
    handles => {
        inc_counter => 'inc',
        dec_counter => 'dec',
    },
);

# apply the observable-role and
# provide methodnames, after which the observers are notified of changes
with 'MooseX::Observer::Role::Observable' => { notify_after => [qw~
    count
    inc_counter
    dec_counter
    reset_counter
~] };

sub reset_counter { shift->count(0) }

sub _utility_method { ... }

############################################################################
package Display;

use Moose;

# apply the oberserver-role, tagging the class as observer and ...
with 'MooseX::Observer::Role::Observer';

# ... require an update-method to be implemented
# this is called after the observed subject calls an observed method
sub update {
    my ( $self, $subject, $args, $eventname ) = @_;
    print $subject->count;
}

############################################################################
package main;

my $counter = Counter->new();
# add an observer of type "Display" to our observable counter
$counter->add_observer( Display->new() );

# increments the counter to 1, afterwards its observers are notified of changes
# Display is notified of a change, its update-method is called 
$counter->inc_counter;  # Display prints 1
$counter->dec_counter;  # Display prints 0

DESCRIPTION

This is a simple role, that you have to apply to your oberservers. It simply requires you to implement a method called update. This method is called everytime the observed object changes.

METHODS

update($subject, $args, $eventname)

This method has to be implemented by the class, that consumes this role. The following arguments are passed.

1. the subject

The object being observed.

2. an arrayref containg arguments

The arguments of method, that was the reason for the observed class' change.

3. an eventname

The name of the method, that was the reason for the observed class' change.

INSTALLATION

See perlmodinstall for information and options on installing Perl modules.

SEE ALSO

Please see those modules/websites for more information related to this module.

• MooseX::Observer

AUTHOR

Thomas Müller <tmueller@cpan.org>

COPYRIGHT AND LICENSE

This software is copyright (c) 2011 by Thomas Müller.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.