7 use Scalar::Util 'blessed';
8 use Carp 'carp', 'confess';
9 use Class::Load 'is_class_loaded';
11 use Moose::Deprecated;
17 die "Class::MOP version $Moose::VERSION required--this is version $Class::MOP::VERSION"
18 if $Moose::VERSION && $Class::MOP::VERSION ne $Moose::VERSION;
21 use Moose::Meta::Class;
22 use Moose::Meta::TypeConstraint;
23 use Moose::Meta::TypeCoercion;
24 use Moose::Meta::Attribute;
25 use Moose::Meta::Instance;
29 use Moose::Meta::Role;
30 use Moose::Meta::Role::Composite;
31 use Moose::Meta::Role::Application;
32 use Moose::Meta::Role::Application::RoleSummation;
33 use Moose::Meta::Role::Application::ToClass;
34 use Moose::Meta::Role::Application::ToRole;
35 use Moose::Meta::Role::Application::ToInstance;
37 use Moose::Util::TypeConstraints;
40 use Moose::Meta::Attribute::Native;
51 Moose->throw_error("Must derive at least one class") unless @_;
53 # this checks the metaclass to make sure
54 # it is correct, sometimes it can get out
55 # of sync when the classes are being built
56 $meta->superclasses(@_);
60 Moose::Util::apply_all_roles(shift, @_);
67 my %context = Moose::Util::_caller_info;
68 $context{context} = 'has declaration';
69 $context{type} = 'class';
71 my @options = ( definition_context => \%context, @_ );
72 my $attrs = ( ref($name) eq 'ARRAY' ) ? $name : [ ($name) ];
73 $meta->add_attribute( $_, @options ) for @$attrs;
77 Moose::Util::add_method_modifier(shift, 'before', \@_);
81 Moose::Util::add_method_modifier(shift, 'after', \@_);
85 Moose::Util::add_method_modifier(shift, 'around', \@_);
94 carp 'Arguments passed to super() are ignored';
97 # This check avoids a recursion loop - see
98 # t/bugs/super_recursion.t
99 return if defined $SUPER_PACKAGE && $SUPER_PACKAGE ne caller();
100 return unless $SUPER_BODY; $SUPER_BODY->(@SUPER_ARGS);
105 my ( $name, $method ) = @_;
106 $meta->add_override_method_modifier( $name => $method );
111 our ( %INNER_BODY, %INNER_ARGS );
113 if ( my $body = $INNER_BODY{$pkg} ) {
114 my @args = @{ $INNER_ARGS{$pkg} };
115 local $INNER_ARGS{$pkg};
116 local $INNER_BODY{$pkg};
117 return $body->(@args);
125 my ( $name, $method ) = @_;
126 $meta->add_augment_method_modifier( $name => $method );
129 Moose::Exporter->setup_import_methods(
131 qw( extends with has before after around override augment )
136 \&Scalar::Util::blessed,
144 my $class = $args{for_class}
145 or Moose->throw_error("Cannot call init_meta without specifying a for_class");
146 my $base_class = $args{base_class} || 'Moose::Object';
147 my $metaclass = $args{metaclass} || 'Moose::Meta::Class';
148 my $meta_name = exists $args{meta_name} ? $args{meta_name} : 'meta';
150 Moose->throw_error("The Metaclass $metaclass must be loaded. (Perhaps you forgot to 'use $metaclass'?)")
151 unless is_class_loaded($metaclass);
153 Moose->throw_error("The Metaclass $metaclass must be a subclass of Moose::Meta::Class.")
154 unless $metaclass->isa('Moose::Meta::Class');
156 # make a subtype for each Moose class
158 unless find_type_constraint($class);
162 if ( $meta = Class::MOP::get_metaclass_by_name($class) ) {
163 unless ( $meta->isa("Moose::Meta::Class") ) {
164 my $error_message = "$class already has a metaclass, but it does not inherit $metaclass ($meta).";
165 if ( $meta->isa('Moose::Meta::Role') ) {
166 Moose->throw_error($error_message . ' You cannot make the same thing a role and a class. Remove either Moose or Moose::Role.');
168 Moose->throw_error($error_message);
174 # now we check whether our ancestors have metaclass, and if so borrow that
175 my ( undef, @isa ) = @{ mro::get_linear_isa($class) };
177 foreach my $ancestor ( @isa ) {
178 my $ancestor_meta = Class::MOP::get_metaclass_by_name($ancestor) || next;
180 my $ancestor_meta_class = $ancestor_meta->_real_ref_name;
182 # if we have an ancestor metaclass that inherits $metaclass, we use
183 # that. This is like _fix_metaclass_incompatibility, but we can do it now.
185 # the case of having an ancestry is not very common, but arises in
187 unless ( $metaclass->isa( $ancestor_meta_class ) ) {
188 if ( $ancestor_meta_class->isa($metaclass) ) {
189 $metaclass = $ancestor_meta_class;
194 $meta = $metaclass->initialize($class);
197 if (defined $meta_name) {
198 # also check for inherited non moose 'meta' method?
199 my $existing = $meta->get_method($meta_name);
200 if ($existing && !$existing->isa('Class::MOP::Method::Meta')) {
201 Carp::cluck "Moose is overwriting an existing method named "
202 . "$meta_name in class $class with a method "
203 . "which returns the class's metaclass. If this is "
204 . "actually what you want, you should remove the "
205 . "existing method, otherwise, you should rename or "
206 . "disable this generated method using the "
207 . "'-meta_name' option to 'use Moose'.";
209 $meta->_add_meta_method($meta_name);
212 # make sure they inherit from Moose::Object
213 $meta->superclasses($base_class)
214 unless $meta->superclasses();
219 # This may be used in some older MooseX extensions.
221 goto &Moose::Exporter::_get_caller;
224 ## make 'em all immutable
227 inline_constructor => 1,
228 constructor_name => "_new",
229 # these are Class::MOP accessors, so they need inlining
230 inline_accessors => 1
231 ) for grep { $_->is_mutable }
234 Moose::Meta::Attribute
236 Moose::Meta::Instance
238 Moose::Meta::TypeCoercion
239 Moose::Meta::TypeCoercion::Union
242 Moose::Meta::Method::Constructor
243 Moose::Meta::Method::Destructor
244 Moose::Meta::Method::Overridden
245 Moose::Meta::Method::Augmented
248 Moose::Meta::Role::Attribute
249 Moose::Meta::Role::Method
250 Moose::Meta::Role::Method::Required
251 Moose::Meta::Role::Method::Conflicting
253 Moose::Meta::Role::Composite
255 Moose::Meta::Role::Application
256 Moose::Meta::Role::Application::RoleSummation
257 Moose::Meta::Role::Application::ToClass
258 Moose::Meta::Role::Application::ToRole
259 Moose::Meta::Role::Application::ToInstance
263 inline_constructor => 0,
264 constructor_name => undef,
265 # these are Class::MOP accessors, so they need inlining
266 inline_accessors => 1
267 ) for grep { $_->is_mutable }
270 Moose::Meta::Method::Accessor
271 Moose::Meta::Method::Delegation
272 Moose::Meta::Mixin::AttributeCore
277 # ABSTRACT: A postmodern object system for Perl 5
286 use Moose; # automatically turns on strict and warnings
288 has 'x' => (is => 'rw', isa => 'Int');
289 has 'y' => (is => 'rw', isa => 'Int');
302 has 'z' => (is => 'rw', isa => 'Int');
304 after 'clear' => sub {
311 Moose is an extension of the Perl 5 object system.
313 The main goal of Moose is to make Perl 5 Object Oriented programming
314 easier, more consistent, and less tedious. With Moose you can think
315 more about what you want to do and less about the mechanics of OOP.
317 Additionally, Moose is built on top of L<Class::MOP>, which is a
318 metaclass system for Perl 5. This means that Moose not only makes
319 building normal Perl 5 objects better, but it provides the power of
320 metaclass programming as well.
324 If you're new to Moose, the best place to start is the
325 L<Moose::Manual> docs, followed by the L<Moose::Cookbook>. The intro
326 will show you what Moose is, and how it makes Perl 5 OO better.
328 The cookbook recipes on Moose basics will get you up to speed with
329 many of Moose's features quickly. Once you have an idea of what Moose
330 can do, you can use the API documentation to get more detail on
331 features which interest you.
333 =head2 Moose Extensions
335 The C<MooseX::> namespace is the official place to find Moose extensions.
336 These extensions can be found on the CPAN. The easiest way to find them
337 is to search for them (L<http://search.cpan.org/search?query=MooseX::>),
338 or to examine L<Task::Moose> which aims to keep an up-to-date, easily
339 installable list of Moose extensions.
343 Much of the Moose documentation has been translated into other languages.
349 Japanese docs can be found at
350 L<http://perldoc.perlassociation.org/pod/Moose-Doc-JA/index.html>. The
351 source POD files can be found in GitHub:
352 L<http://github.com/jpa/Moose-Doc-JA>
356 =head1 BUILDING CLASSES WITH MOOSE
358 Moose makes every attempt to provide as much convenience as possible during
359 class construction/definition, but still stay out of your way if you want it
360 to. Here are a few items to note when building classes with Moose.
362 When you C<use Moose>, Moose will set the class's parent class to
363 L<Moose::Object>, I<unless> the class using Moose already has a parent
364 class. In addition, specifying a parent with C<extends> will change the parent
367 Moose will also manage all attributes (including inherited ones) that are
368 defined with C<has>. And (assuming you call C<new>, which is inherited from
369 L<Moose::Object>) this includes properly initializing all instance slots,
370 setting defaults where appropriate, and performing any type constraint checking
373 =head1 PROVIDED METHODS
375 Moose provides a number of methods to all your classes, mostly through the
376 inheritance of L<Moose::Object>. There is however, one exception.
382 This is a method which provides access to the current class's metaclass.
386 =head1 EXPORTED FUNCTIONS
388 Moose will export a number of functions into the class's namespace which
389 may then be used to set up the class. These functions all work directly
390 on the current class.
394 =item B<extends (@superclasses)>
396 This function will set the superclass(es) for the current class.
398 This approach is recommended instead of C<use base>, because C<use base>
399 actually C<push>es onto the class's C<@ISA>, whereas C<extends> will
400 replace it. This is important to ensure that classes which do not have
401 superclasses still properly inherit from L<Moose::Object>.
403 Each superclass can be followed by a hash reference with options. Currently,
404 only L<-version|Class::MOP/Class Loading Options> is recognized:
406 extends 'My::Parent' => { -version => 0.01 },
407 'My::OtherParent' => { -version => 0.03 };
409 An exception will be thrown if the version requirements are not
412 =item B<with (@roles)>
414 This will apply a given set of C<@roles> to the local class.
416 Like with C<extends>, each specified role can be followed by a hash
417 reference with a L<-version|Class::MOP/Class Loading Options> option:
419 with 'My::Role' => { -version => 0.32 },
420 'My::Otherrole' => { -version => 0.23 };
422 The specified version requirements must be satisfied, otherwise an
423 exception will be thrown.
425 If your role takes options or arguments, they can be passed along in the
426 hash reference as well.
428 =item B<has $name|@$names =E<gt> %options>
430 This will install an attribute of a given C<$name> into the current class. If
431 the first parameter is an array reference, it will create an attribute for
432 every C<$name> in the list. The C<%options> will be passed to the constructor
433 for L<Moose::Meta::Attribute> (which inherits from L<Class::MOP::Attribute>),
434 so the full documentation for the valid options can be found there. These are
435 the most commonly used options:
439 =item I<is =E<gt> 'rw'|'ro'>
441 The I<is> option accepts either I<rw> (for read/write) or I<ro> (for read
442 only). These will create either a read/write accessor or a read-only
443 accessor respectively, using the same name as the C<$name> of the attribute.
445 If you need more control over how your accessors are named, you can
446 use the L<reader|Class::MOP::Attribute/reader>,
447 L<writer|Class::MOP::Attribute/writer> and
448 L<accessor|Class::MOP::Attribute/accessor> options inherited from
449 L<Class::MOP::Attribute>, however if you use those, you won't need the
452 =item I<isa =E<gt> $type_name>
454 The I<isa> option uses Moose's type constraint facilities to set up runtime
455 type checking for this attribute. Moose will perform the checks during class
456 construction, and within any accessors. The C<$type_name> argument must be a
457 string. The string may be either a class name or a type defined using
458 Moose's type definition features. (Refer to L<Moose::Util::TypeConstraints>
459 for information on how to define a new type, and how to retrieve type meta-data).
461 =item I<coerce =E<gt> (1|0)>
463 This will attempt to use coercion with the supplied type constraint to change
464 the value passed into any accessors or constructors. You B<must> supply a type
465 constraint, and that type constraint B<must> define a coercion. See
466 L<Moose::Cookbook::Basics::HTTP_SubtypesAndCoercion> for an example.
468 =item I<does =E<gt> $role_name>
470 This will accept the name of a role which the value stored in this attribute
471 is expected to have consumed.
473 =item I<required =E<gt> (1|0)>
475 This marks the attribute as being required. This means a value must be
476 supplied during class construction, I<or> the attribute must be lazy
477 and have either a default or a builder. Note that c<required> does not
478 say anything about the attribute's value, which can be C<undef>.
480 =item I<weak_ref =E<gt> (1|0)>
482 This will tell the class to store the value of this attribute as a weakened
483 reference. If an attribute is a weakened reference, it B<cannot> also be
484 coerced. Note that when a weak ref expires, the attribute's value becomes
485 undefined, and is still considered to be set for purposes of predicate,
488 =item I<lazy =E<gt> (1|0)>
490 This will tell the class to not create this slot until absolutely necessary.
491 If an attribute is marked as lazy it B<must> have a default or builder
494 =item I<trigger =E<gt> $code>
496 The I<trigger> option is a CODE reference which will be called after
497 the value of the attribute is set. The CODE ref is passed the
498 instance itself, the updated value, and the original value if the
499 attribute was already set.
501 You B<can> have a trigger on a read-only attribute.
503 B<NOTE:> Triggers will only fire when you B<assign> to the attribute,
504 either in the constructor, or using the writer. Default and built values will
505 B<not> cause the trigger to be fired.
507 =item I<handles =E<gt> ARRAY | HASH | REGEXP | ROLE | ROLETYPE | DUCKTYPE | CODE>
509 The I<handles> option provides Moose classes with automated delegation features.
510 This is a pretty complex and powerful option. It accepts many different option
511 formats, each with its own benefits and drawbacks.
513 B<NOTE:> The class being delegated to does not need to be a Moose based class,
514 which is why this feature is especially useful when wrapping non-Moose classes.
516 All I<handles> option formats share the following traits:
518 You cannot override a locally defined method with a delegated method; an
519 exception will be thrown if you try. That is to say, if you define C<foo> in
520 your class, you cannot override it with a delegated C<foo>. This is almost never
521 something you would want to do, and if it is, you should do it by hand and not
524 You cannot override any of the methods found in Moose::Object, or the C<BUILD>
525 and C<DEMOLISH> methods. These will not throw an exception, but will silently
526 move on to the next method in the list. My reasoning for this is that you would
527 almost never want to do this, since it usually breaks your class. As with
528 overriding locally defined methods, if you do want to do this, you should do it
529 manually, not with Moose.
531 You do not I<need> to have a reader (or accessor) for the attribute in order
532 to delegate to it. Moose will create a means of accessing the value for you,
533 however this will be several times B<less> efficient then if you had given
534 the attribute a reader (or accessor) to use.
536 Below is the documentation for each option format:
542 This is the most common usage for I<handles>. You basically pass a list of
543 method names to be delegated, and Moose will install a delegation method
548 This is the second most common usage for I<handles>. Instead of a list of
549 method names, you pass a HASH ref where each key is the method name you
550 want installed locally, and its value is the name of the original method
551 in the class being delegated to.
553 This can be very useful for recursive classes like trees. Here is a
554 quick example (soon to be expanded into a Moose::Cookbook recipe):
559 has 'node' => (is => 'rw', isa => 'Any');
564 default => sub { [] }
572 parent_node => 'node',
573 siblings => 'children',
577 In this example, the Tree package gets C<parent_node> and C<siblings> methods,
578 which delegate to the C<node> and C<children> methods (respectively) of the Tree
579 instance stored in the C<parent> slot.
581 You may also use an array reference to curry arguments to the original method.
585 handles => { set_foo => [ set => 'foo' ] },
588 # $self->set_foo(...) calls $self->thing->set('foo', ...)
590 The first element of the array reference is the original method name, and the
591 rest is a list of curried arguments.
595 The regexp option works very similar to the ARRAY option, except that it builds
596 the list of methods for you. It starts by collecting all possible methods of the
597 class being delegated to, then filters that list using the regexp supplied here.
599 B<NOTE:> An I<isa> option is required when using the regexp option format. This
600 is so that we can determine (at compile time) the method list from the class.
601 Without an I<isa> this is just not possible.
603 =item C<ROLE> or C<ROLETYPE>
605 With the role option, you specify the name of a role or a
606 L<role type|Moose::Meta::TypeConstraint::Role> whose "interface" then becomes
607 the list of methods to handle. The "interface" can be defined as; the methods
608 of the role and any required methods of the role. It should be noted that this
609 does B<not> include any method modifiers or generated attribute methods (which
610 is consistent with role composition).
614 With the duck type option, you pass a duck type object whose "interface" then
615 becomes the list of methods to handle. The "interface" can be defined as the
616 list of methods passed to C<duck_type> to create a duck type object. For more
617 information on C<duck_type> please check
618 L<Moose::Util::TypeConstraints>.
622 This is the option to use when you really want to do something funky. You should
623 only use it if you really know what you are doing, as it involves manual
626 This takes a code reference, which should expect two arguments. The first is the
627 attribute meta-object this I<handles> is attached to. The second is the
628 metaclass of the class being delegated to. It expects you to return a hash (not
629 a HASH ref) of the methods you want mapped.
633 =item I<traits =E<gt> [ @role_names ]>
635 This tells Moose to take the list of C<@role_names> and apply them to the
636 attribute meta-object. Custom attribute metaclass traits are useful for
637 extending the capabilities of the I<has> keyword: they are the simplest way to
638 extend the MOP, but they are still a fairly advanced topic and too much to
641 See L<Metaclass and Trait Name Resolution> for details on how a trait name is
642 resolved to a role name.
644 Also see L<Moose::Cookbook::Meta::Labeled_AttributeTrait> for a metaclass
647 =item I<builder> => Str
649 The value of this key is the name of the method that will be called to obtain
650 the value used to initialize the attribute. See the L<builder option docs in
651 Class::MOP::Attribute|Class::MOP::Attribute/builder> and/or
652 L<Moose::Cookbook::Basics::BinaryTree_BuilderAndLazyBuild> for more
655 =item I<default> => SCALAR | CODE
657 The value of this key is the default value which will initialize the attribute.
659 NOTE: If the value is a simple scalar (string or number), then it can
660 be just passed as is. However, if you wish to initialize it with a
661 HASH or ARRAY ref, then you need to wrap that inside a CODE reference.
662 See the L<default option docs in
663 Class::MOP::Attribute|Class::MOP::Attribute/default> for more
666 =item I<clearer> => Str
668 Creates a method allowing you to clear the value. See the L<clearer option
669 docs in Class::MOP::Attribute|Class::MOP::Attribute/clearer> for more
672 =item I<predicate> => Str
674 Creates a method to perform a basic test to see if a value has been set in the
675 attribute. See the L<predicate option docs in
676 Class::MOP::Attribute|Class::MOP::Attribute/predicate> for more information.
678 Note that the predicate will return true even for a C<weak_ref> attribute
679 whose value has expired.
681 =item I<documentation> => $string
683 An arbitrary string that can be retrieved later by calling C<<
684 $attr->documentation >>.
690 =item B<has +$name =E<gt> %options>
692 This is variation on the normal attribute creator C<has> which allows you to
693 clone and extend an attribute from a superclass or from a role. Here is an
694 example of the superclass usage:
702 default => 'Hello, I am a Foo'
710 has '+message' => (default => 'Hello I am My::Foo');
712 What is happening here is that B<My::Foo> is cloning the C<message> attribute
713 from its parent class B<Foo>, retaining the C<is =E<gt> 'rw'> and C<isa =E<gt>
714 'Str'> characteristics, but changing the value in C<default>.
716 Here is another example, but within the context of a role:
724 default => 'Hello, I am a Foo'
732 has '+message' => (default => 'Hello I am My::Foo');
734 In this case, we are basically taking the attribute which the role supplied
735 and altering it within the bounds of this feature.
737 Note that you can only extend an attribute from either a superclass or a role,
738 you cannot extend an attribute in a role that composes over an attribute from
741 Aside from where the attributes come from (one from superclass, the other
742 from a role), this feature works exactly the same. This feature is restricted
743 somewhat, so as to try and force at least I<some> sanity into it. Most options work the same, but there are some exceptions:
757 These options can be added, but cannot override a superclass definition.
761 You are allowed to B<add> additional traits to the C<traits> definition.
762 These traits will be composed into the attribute, but preexisting traits
763 B<are not> overridden, or removed.
767 =item B<before $name|@names|\@names|qr/.../ =E<gt> sub { ... }>
769 =item B<after $name|@names|\@names|qr/.../ =E<gt> sub { ... }>
771 =item B<around $name|@names|\@names|qr/.../ =E<gt> sub { ... }>
773 These three items are syntactic sugar for the before, after, and around method
774 modifier features that L<Class::MOP> provides. More information on these may be
775 found in L<Moose::Manual::MethodModifiers> and the
776 L<Class::MOP::Class documentation|Class::MOP::Class/"Method Modifiers">.
778 =item B<override ($name, &sub)>
780 An C<override> method is a way of explicitly saying "I am overriding this
781 method from my superclass". You can call C<super> within this method, and
782 it will work as expected. The same thing I<can> be accomplished with a normal
783 method call and the C<SUPER::> pseudo-package; it is really your choice.
787 The keyword C<super> is a no-op when called outside of an C<override> method. In
788 the context of an C<override> method, it will call the next most appropriate
789 superclass method with the same arguments as the original method.
791 =item B<augment ($name, &sub)>
793 An C<augment> method, is a way of explicitly saying "I am augmenting this
794 method from my superclass". Once again, the details of how C<inner> and
795 C<augment> work is best described in the
796 L<Moose::Cookbook::Basics::Document_AugmentAndInner>.
800 The keyword C<inner>, much like C<super>, is a no-op outside of the context of
801 an C<augment> method. You can think of C<inner> as being the inverse of
802 C<super>; the details of how C<inner> and C<augment> work is best described in
803 the L<Moose::Cookbook::Basics::Document_AugmentAndInner>.
807 This is the C<Scalar::Util::blessed> function. It is highly recommended that
808 this is used instead of C<ref> anywhere you need to test for an object's class
813 This is the C<Carp::confess> function, and exported here for historical
820 When you use Moose, you can specify traits which will be applied to your
823 use Moose -traits => 'My::Trait';
825 This is very similar to the attribute traits feature. When you do
826 this, your class's C<meta> object will have the specified traits
827 applied to it. See L<Metaclass and Trait Name Resolution> for more
830 =head2 Metaclass and Trait Name Resolution
832 By default, when given a trait name, Moose simply tries to load a
833 class of the same name. If such a class does not exist, it then looks
834 for for a class matching
835 B<Moose::Meta::$type::Custom::Trait::$trait_name>. The C<$type>
836 variable here will be one of B<Attribute> or B<Class>, depending on
837 what the trait is being applied to.
839 If a class with this long name exists, Moose checks to see if it has
840 the method C<register_implementation>. This method is expected to
841 return the I<real> class name of the trait. If there is no
842 C<register_implementation> method, it will fall back to using
843 B<Moose::Meta::$type::Custom::Trait::$trait> as the trait name.
845 The lookup method for metaclasses is the same, except that it looks
846 for a class matching B<Moose::Meta::$type::Custom::$metaclass_name>.
848 If all this is confusing, take a look at
849 L<Moose::Cookbook::Meta::Labeled_AttributeTrait>, which demonstrates how to
850 create an attribute trait.
852 =head1 UNIMPORTING FUNCTIONS
856 Moose offers a way to remove the keywords it exports, through the C<unimport>
857 method. You simply have to say C<no Moose> at the bottom of your code for this
858 to work. Here is an example:
863 has 'first_name' => (is => 'rw', isa => 'Str');
864 has 'last_name' => (is => 'rw', isa => 'Str');
868 $self->first_name . ' ' . $self->last_name
871 no Moose; # keywords are removed from the Person package
873 =head1 EXTENDING AND EMBEDDING MOOSE
875 To learn more about extending Moose, we recommend checking out the
876 "Extending" recipes in the L<Moose::Cookbook>, starting with
877 L<Moose::Cookbook::Extending::ExtensionOverview>, which provides an overview of
878 all the different ways you might extend Moose. L<Moose::Exporter> and
879 L<Moose::Util::MetaRole> are the modules which provide the majority of the
880 extension functionality, so reading their documentation should also be helpful.
882 =head2 The MooseX:: namespace
884 Generally if you're writing an extension I<for> Moose itself you'll want
885 to put your extension in the C<MooseX::> namespace. This namespace is
886 specifically for extensions that make Moose better or different in some
887 fundamental way. It is traditionally B<not> for a package that just happens
888 to use Moose. This namespace follows from the examples of the C<LWPx::>
889 and C<DBIx::> namespaces that perform the same function for C<LWP> and C<DBI>
892 =head1 METACLASS COMPATIBILITY AND MOOSE
894 Metaclass compatibility is a thorny subject. You should start by
895 reading the "About Metaclass compatibility" section in the
898 Moose will attempt to resolve a few cases of metaclass incompatibility
899 when you set the superclasses for a class, in addition to the cases that
900 C<Class::MOP> handles.
902 Moose tries to determine if the metaclasses only "differ by roles". This
903 means that the parent and child's metaclass share a common ancestor in
904 their respective hierarchies, and that the subclasses under the common
905 ancestor are only different because of role applications. This case is
906 actually fairly common when you mix and match various C<MooseX::*>
907 modules, many of which apply roles to the metaclass.
909 If the parent and child do differ by roles, Moose replaces the
910 metaclass in the child with a newly created metaclass. This metaclass
911 is a subclass of the parent's metaclass which does all of the roles that
912 the child's metaclass did before being replaced. Effectively, this
913 means the new metaclass does all of the roles done by both the
914 parent's and child's original metaclasses.
916 Ultimately, this is all transparent to you except in the case of an
917 unresolvable conflict.
925 It should be noted that C<super> and C<inner> B<cannot> be used in the same
926 method. However, they may be combined within the same class hierarchy; see
927 F<t/basics/override_augment_inner_super.t> for an example.
929 The reason for this is that C<super> is only valid within a method
930 with the C<override> modifier, and C<inner> will never be valid within an
931 C<override> method. In fact, C<augment> will skip over any C<override> methods
932 when searching for its appropriate C<inner>.
934 This might seem like a restriction, but I am of the opinion that keeping these
935 two features separate (yet interoperable) actually makes them easy to use, since
936 their behavior is then easier to predict. Time will tell whether I am right or
937 not (UPDATE: so far so good).
943 We offer both a mailing list and a very active IRC channel.
945 The mailing list is L<mailto:moose@perl.org>. You must be subscribed to send
946 a message. To subscribe, send an empty message to
947 L<mailto:moose-subscribe@perl.org>
949 You can also visit us at C<#moose> on L<irc://irc.perl.org/#moose>
950 This channel is quite active, and questions at all levels (on Moose-related
951 topics ;) are welcome.
953 =head1 WHAT DOES MOOSE STAND FOR?
955 Moose doesn't stand for one thing in particular, however, if you want, here
956 are a few of our favorites, feel free to contribute more.
960 =item * Make Other Object Systems Envious
962 =item * Makes Object Orientation So Easy
964 =item * Makes Object Orientation Spiffy- Er (sorry ingy)
966 =item * Most Other Object Systems Emasculate
968 =item * Moose Often Ovulate Sorta Early
970 =item * Moose Offers Often Super Extensions
972 =item * Meta Object Obligates Salivary Excitation
974 =item * Meta Object Orientation Syntax Extensions
978 =head1 ACKNOWLEDGEMENTS
982 =item I blame Sam Vilain for introducing me to the insanity that is meta-models.
984 =item I blame Audrey Tang for then encouraging my meta-model habit in #perl6.
986 =item Without Yuval "nothingmuch" Kogman this module would not be possible,
987 and it certainly wouldn't have this name ;P
989 =item The basis of the TypeContraints module was Rob Kinyon's idea
990 originally, I just ran with it.
992 =item Thanks to mst & chansen and the whole #moose posse for all the
993 early ideas/feature-requests/encouragement/bug-finding.
995 =item Thanks to David "Theory" Wheeler for meta-discussions and spelling fixes.
1003 =item L<http://www.iinteractive.com/moose>
1005 This is the official web home of Moose. It contains links to our public git
1006 repository, as well as links to a number of talks and articles on Moose and
1007 Moose related technologies.
1009 =item the L<Moose manual|Moose::Manual>
1011 This is an introduction to Moose which covers most of the basics.
1013 =item Modern Perl, by chromatic
1015 This is an introduction to modern Perl programming, which includes a section on
1016 Moose. It is available in print and as a free download from
1017 L<http://onyxneon.com/books/modern_perl/>.
1019 =item The Moose is flying, a tutorial by Randal Schwartz
1021 Part 1 - L<http://www.stonehenge.com/merlyn/LinuxMag/col94.html>
1023 Part 2 - L<http://www.stonehenge.com/merlyn/LinuxMag/col95.html>
1025 =item Several Moose extension modules in the C<MooseX::> namespace.
1027 See L<http://search.cpan.org/search?query=MooseX::> for extensions.
1035 =item The Art of the MetaObject Protocol
1037 I mention this in the L<Class::MOP> docs too, as this book was critical in
1038 the development of both modules and is highly recommended.
1046 =item L<http://www.cs.utah.edu/plt/publications/oopsla04-gff.pdf>
1048 This paper (suggested by lbr on #moose) was what lead to the implementation
1049 of the C<super>/C<override> and C<inner>/C<augment> features. If you really
1050 want to understand them, I suggest you read this.
1056 All complex software has bugs lurking in it, and this module is no
1059 Please report any bugs to C<bug-moose@rt.cpan.org>, or through the web
1060 interface at L<http://rt.cpan.org>.
1062 You can also discuss feature requests or possible bugs on the Moose mailing
1063 list (moose@perl.org) or on IRC at L<irc://irc.perl.org/#moose>.
1065 =head1 FEATURE REQUESTS
1067 We are very strict about what features we add to the Moose core, especially
1068 the user-visible features. Instead we have made sure that the underlying
1069 meta-system of Moose is as extensible as possible so that you can add your
1070 own features easily.
1072 That said, occasionally there is a feature needed in the meta-system
1073 to support your planned extension, in which case you should either
1074 email the mailing list (moose@perl.org) or join us on IRC at
1075 L<irc://irc.perl.org/#moose> to discuss. The
1076 L<Moose::Manual::Contributing> has more detail about how and when you
1081 There are only a few people with the rights to release a new version
1082 of Moose. The Moose Cabal are the people to go to with questions regarding
1083 the wider purview of Moose. They help maintain not just the code
1084 but the community as well.
1086 Stevan (stevan) Little E<lt>stevan@iinteractive.comE<gt>
1088 Jesse (doy) Luehrs E<lt>doy at tozt dot netE<gt>
1090 Yuval (nothingmuch) Kogman
1092 Shawn (sartak) Moore E<lt>sartak@bestpractical.comE<gt>
1094 Hans Dieter (confound) Pearcey E<lt>hdp@pobox.comE<gt>
1096 Chris (perigrin) Prather
1098 Florian Ragwitz E<lt>rafl@debian.orgE<gt>
1100 Dave (autarch) Rolsky E<lt>autarch@urth.orgE<gt>
1104 Moose is a community project, and as such, involves the work of many, many
1105 members of the community beyond just the members in the cabal. In particular:
1107 Dave (autarch) Rolsky wrote most of the documentation in L<Moose::Manual>.
1109 John (jgoulah) Goulah wrote L<Moose::Cookbook::Snack::Keywords>.
1111 Jess (castaway) Robinson wrote L<Moose::Cookbook::Snack::Types>.
1113 Aran (bluefeet) Clary Deltac wrote
1114 L<Moose::Cookbook::Basics::Genome_OverloadingSubtypesAndCoercion>.
1116 Anders (Debolaz) Nor Berle contributed L<Test::Moose> and L<Moose::Util>.
1118 Also, the code in L<Moose::Meta::Attribute::Native> is based on code from the
1119 L<MooseX::AttributeHelpers> distribution, which had contributions from:
1121 Chris (perigrin) Prather
1127 Florian (rafl) Ragwitz
1135 Paul (frodwith) Driver
1141 Robert (phaylon) Sedlacek
1143 Shawn (Sartak) Moore
1151 Finally, these people also contributed various tests, bug fixes,
1152 documentation, and features to the Moose codebase:
1156 Adam (Alias) Kennedy
1158 Christian (chansen) Hansen
1162 Dylan Hardison (doc fixes)
1164 Eric (ewilhelm) Wilhelm
1168 Guillermo (groditi) Roditi
1174 Jonathan (jrockway) Rockway
1178 Nathan (kolibrie) Gray
1180 Paul (frodwith) Driver
1182 Piotr (dexter) Roszatycki
1186 Robert (phaylon) Sedlacek
1190 Sam (mugwump) Vilain
1192 Scott (konobi) McWhirter
1194 Shlomi (rindolf) Fish
1198 Wallace (wreis) Reis
1200 ... and many other #moose folks