oracular (3) Moose::Manual::Classes.3pm.gz

NAME

       Moose::Manual::Classes - Making your classes use Moose (and subclassing)

VERSION

       version 2.2207

USING MOOSE

       Using Moose is very simple, you just "use Moose":

         package Person;

         use Moose;

       That's it, you've made a class with Moose!

       There's actually a lot going on here under the hood, so let's step through it.

       When you load Moose, a bunch of sugar functions are exported into your class, such as "extends", "has",
       "with", and more. These functions are what you use to define your class. For example, you might define an
       attribute ...

         package Person;

         use Moose;

         has 'ssn' => ( is => 'rw' );

       Attributes are described in the Moose::Manual::Attributes documentation.

       Loading Moose also enables the "strict" and "warnings" pragmas in your class.

       When you load Moose, your class will become a subclass of Moose::Object. The Moose::Object class provides
       a default constructor and destructor, as well as object construction helper methods. You can read more
       about this in the Moose::Manual::Construction document.

       As a convenience, Moose creates a new class type for your class. See the Moose::Manual::Types document to
       learn more about types.

       It also creates a Moose::Meta::Class object for your class. This metaclass object is now available by
       calling a "meta" method on your class, for example "Person->meta".

       The metaclass object provides an introspection API for your class. It is also used by Moose itself under
       the hood to add attributes, define parent classes, and so on. In fact, all of Moose's sugar does the real
       work by calling methods on this metaclass object (and other meta API objects).

SUBCLASSING

       Moose provides a simple sugar function for declaring your parent classes, "extends":

         package User;

         use Moose;

         extends 'Person';

         has 'username' => ( is => 'rw' );

       Note that each call to "extends" will reset your parents. For multiple inheritance you must provide all
       the parents at once, "extends 'Foo', 'Bar'".

       When you call "extends" Moose will try to load any classes you pass.

       You can use Moose to extend a non-Moose parent. However, when you do this, you will inherit the parent
       class's constructor (assuming it is also called "new"). In that case, you will have to take care of
       initializing attributes manually, either in the parent's constructor, or in your subclass, and you will
       lose a lot of Moose magic.

       See the MooseX::NonMoose module on CPAN if you're interested in extending non-Moose parent classes with
       Moose child classes.

CLEANING UP MOOSE DROPPINGS

       Moose exports a number of functions into your class. It's a good idea to remove these sugar functions
       from your class's namespace, so that "Person->can('has')" will no longer return true.

       There are several ways to do this. We recommend using namespace::autoclean, a CPAN module. Not only will
       it remove Moose exports, it will also remove any other exports.

         package Person;

         use namespace::autoclean;

         use Moose;

       If you absolutely can't use a CPAN module (but can use Moose?), you can write "no Moose" at the end of
       your class. This will remove any Moose exports in your class.

         package Person;

         use Moose;

         has 'ssn' => ( is => 'rw' );

         no Moose;

MAKING IT FASTER

       Moose has a feature called "immutabilization" that you can use to greatly speed up your classes at
       runtime. However, using it incurs a cost when your class is first being loaded. When you make your class
       immutable you tell Moose that you will not be changing it in the future. You will not be adding any more
       attributes, methods, roles, etc.

       This allows Moose to generate code specific to your class. In particular, it creates an "inline"
       constructor, making object construction much faster.

       To make your class immutable you simply call "make_immutable" on your class's metaclass object.

         __PACKAGE__->meta->make_immutable;

   Immutabilization and new()
       If you override new() in your class, then the immutabilization code will not be able to provide an
       optimized constructor for your class. Instead, you should use a BUILD() method, which will be called from
       the inlined constructor.

       Alternately, if you really need to provide a different new(), you can also provide your own
       immutabilization method. Doing so requires extending the Moose metaclasses, and is well beyond the scope
       of this manual.

INSTANTIATING CLASSES

       When you're ready to use Moose classes in an application, reference them in your code in the regular Perl
       OO way by including a "use" directive at the top of the file where the objects should be created.

         use Person;

         my $person = Person->new(
           # attribute values at instantiation
           # go here
           ssn => '123456789',
         );

AUTHORS

       •   Stevan Little <stevan@cpan.org>

       •   Dave Rolsky <autarch@urth.org>

       •   Jesse Luehrs <doy@cpan.org>

       •   Shawn M Moore <sartak@cpan.org>

       •   יובל קוג'מן (Yuval Kogman) <nothingmuch@woobling.org>

       •   Karen Etheridge <ether@cpan.org>

       •   Florian Ragwitz <rafl@debian.org>

       •   Hans Dieter Pearcey <hdp@cpan.org>

       •   Chris Prather <chris@prather.org>

       •   Matt S Trout <mstrout@cpan.org>

COPYRIGHT AND LICENSE

       This software is copyright (c) 2006 by Infinity Interactive, Inc.

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