MooseX::Role::ParameteUserdContributed Perl DocuMooseX::Role::Parameterized(3)NAME
MooseX::Role::Parameterized - roles with composition parameters
SYNOPSIS
package Counter;
use MooseX::Role::Parameterized;
parameter name => (
isa => 'Str',
required => 1,
);
role {
my $p = shift;
my $name = $p->name;
has $name => (
is => 'rw',
isa => 'Int',
default => 0,
);
method "increment_$name" => sub {
my $self = shift;
$self->$name($self->$name + 1);
};
method "reset_$name" => sub {
my $self = shift;
$self->$name(0);
};
};
package MyGame::Weapon;
use Moose;
with Counter => { name => 'enchantment' };
package MyGame::Wand;
use Moose;
with Counter => { name => 'zapped' };
MooseX::Role::Parameterized::Tutorial
Stop! If you're new here, please read
MooseX::Role::Parameterized::Tutorial for a much gentler introduction.
DESCRIPTION
Your parameterized role consists of two new things: parameter
declarations and a "role" block.
Parameters are declared using the "parameter" keyword which very much
resembles "has" in Moose. You can use any option that "has" in Moose
accepts. The default value for the "is" option is "ro" as that's a very
common case. Use "is => 'bare'" if you want no accessor. These
parameters will get their values when the consuming class (or role)
uses "with" in Moose. A parameter object will be constructed with these
values, and passed to the "role" block.
The "role" block then uses the usual Moose::Role keywords to build up a
role. You can shift off the parameter object to inspect what the
consuming class provided as parameters. You use the parameters to
customize your role however you wish.
There are many possible implementations for parameterized roles
(hopefully with a consistent enough API); I believe this to be the
easiest and most flexible design. Coincidentally, Pugs originally had
an eerily similar design.
See MooseX::Role::Parameterized::Extending for some tips on how to
extend this module.
Why a parameters object?
I've been asked several times "Why use a parameter object and not just
a parameter hashref? That would eliminate the need to explicitly
declare your parameters."
The benefits of using an object are similar to the benefits of using
Moose. You get an easy way to specify lazy defaults, type constraint,
delegation, and so on. You get to use MooseX modules.
You also get the usual introspective and intercessory abilities that
come standard with the metaobject protocol. Ambitious users should be
able to add traits to the parameters metaclass to further customize
behavior. Please let me know if you're doing anything viciously
complicated with this extension. :)
CAVEATS
You must use this syntax to declare methods in the role block: "method
NAME => sub { ... };". This is due to a limitation in Perl. In return
though you can use parameters in your methods!
AUTHOR
Shawn M Moore, "sartak@gmail.com"
SEE ALSO
http://sartak.org/2009/01/parametric-roles-in-perl-5.html
<http://sartak.org/2009/01/parametric-roles-in-perl-5.html>
http://sartak.org/2009/05/the-design-of-parameterized-roles.html
<http://sartak.org/2009/05/the-design-of-parameterized-roles.html>
http://stevan-little.blogspot.com/2009/07/thoughts-on-parameterized-roles.html
<http://stevan-little.blogspot.com/2009/07/thoughts-on-parameterized-
roles.html>
<http://perldition.org/articles/Parameterized%20Roles%20with%20MooseX::Declare.pod>
http://www.modernperlbooks.com/mt/2011/01/the-parametric-role-of-my-mvc-plugin-system.html
<http://www.modernperlbooks.com/mt/2011/01/the-parametric-role-of-my-
mvc-plugin-system.html>
http://jjnapiorkowski.typepad.com/modern-perl/2010/08/parameterized-roles-and-method-traits-redo.html
<http://jjnapiorkowski.typepad.com/modern-perl/2010/08/parameterized-
roles-and-method-traits-redo.html>
http://sartak.org/talks/yapc-asia-2009/(parameterized)-roles/
<http://sartak.org/talks/yapc-asia-2009/(parameterized)-roles/>
https://github.com/SamuraiJack/JooseX-Role-Parameterized
<https://github.com/SamuraiJack/JooseX-Role-Parameterized> - this
extension ported to JavaScript's Joose
COPYRIGHT AND LICENSE
Copyright 2007-2010 Infinity Interactive
This program is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.
perl v5.16.2 2012-01-12 MooseX::Role::Parameterized(3)
