8 $VERSION = eval $VERSION;
9 our $AUTHORITY = 'cpan:STEVAN';
11 use Scalar::Util 'blessed';
14 use Moose::Deprecated;
19 use Moose::Meta::Class;
20 use Moose::Meta::TypeConstraint;
21 use Moose::Meta::TypeCoercion;
22 use Moose::Meta::Attribute;
23 use Moose::Meta::Instance;
27 use Moose::Meta::Role;
28 use Moose::Meta::Role::Composite;
29 use Moose::Meta::Role::Application;
30 use Moose::Meta::Role::Application::RoleSummation;
31 use Moose::Meta::Role::Application::ToClass;
32 use Moose::Meta::Role::Application::ToRole;
33 use Moose::Meta::Role::Application::ToInstance;
35 use Moose::Util::TypeConstraints;
38 use Moose::Meta::Attribute::Native;
49 Moose->throw_error("Must derive at least one class") unless @_;
51 # this checks the metaclass to make sure
52 # it is correct, sometimes it can get out
53 # of sync when the classes are being built
54 $meta->superclasses(@_);
58 Moose::Util::apply_all_roles(shift, @_);
65 Moose->throw_error('Usage: has \'name\' => ( key => value, ... )')
68 my %options = ( definition_context => Moose::Util::_caller_info(), @_ );
69 my $attrs = ( ref($name) eq 'ARRAY' ) ? $name : [ ($name) ];
70 $meta->add_attribute( $_, %options ) for @$attrs;
74 Moose::Util::add_method_modifier(shift, 'before', \@_);
78 Moose::Util::add_method_modifier(shift, 'after', \@_);
82 Moose::Util::add_method_modifier(shift, 'around', \@_);
90 # This check avoids a recursion loop - see
91 # t/100_bugs/020_super_recursion.t
92 return if defined $SUPER_PACKAGE && $SUPER_PACKAGE ne caller();
93 return unless $SUPER_BODY; $SUPER_BODY->(@SUPER_ARGS);
98 my ( $name, $method ) = @_;
99 $meta->add_override_method_modifier( $name => $method );
104 our ( %INNER_BODY, %INNER_ARGS );
106 if ( my $body = $INNER_BODY{$pkg} ) {
107 my @args = @{ $INNER_ARGS{$pkg} };
108 local $INNER_ARGS{$pkg};
109 local $INNER_BODY{$pkg};
110 return $body->(@args);
118 my ( $name, $method ) = @_;
119 $meta->add_augment_method_modifier( $name => $method );
122 Moose::Exporter->setup_import_methods(
124 qw( extends with has before after around override augment )
129 \&Scalar::Util::blessed,
134 # This used to be called as a function. This hack preserves
135 # backwards compatibility.
136 if ( $_[0] ne __PACKAGE__ ) {
137 Moose::Deprecated::deprecated(
138 feature => 'Moose::init_meta',
139 message => 'Calling Moose::init_meta as a function is deprecated',
142 return __PACKAGE__->init_meta(
152 my $class = $args{for_class}
153 or Moose->throw_error("Cannot call init_meta without specifying a for_class");
154 my $base_class = $args{base_class} || 'Moose::Object';
155 my $metaclass = $args{metaclass} || 'Moose::Meta::Class';
157 Moose->throw_error("The Metaclass $metaclass must be a subclass of Moose::Meta::Class.")
158 unless $metaclass->isa('Moose::Meta::Class');
160 # make a subtype for each Moose class
162 unless find_type_constraint($class);
166 if ( $meta = Class::MOP::get_metaclass_by_name($class) ) {
167 unless ( $meta->isa("Moose::Meta::Class") ) {
168 my $error_message = "$class already has a metaclass, but it does not inherit $metaclass ($meta).";
169 if ( $meta->isa('Moose::Meta::Role') ) {
170 Moose->throw_error($error_message . ' You cannot make the same thing a role and a class. Remove either Moose or Moose::Role.');
172 Moose->throw_error($error_message);
178 # now we check whether our ancestors have metaclass, and if so borrow that
179 my ( undef, @isa ) = @{ mro::get_linear_isa($class) };
181 foreach my $ancestor ( @isa ) {
182 my $ancestor_meta = Class::MOP::get_metaclass_by_name($ancestor) || next;
184 my $ancestor_meta_class = $ancestor_meta->_real_ref_name;
186 # if we have an ancestor metaclass that inherits $metaclass, we use
187 # that. This is like _fix_metaclass_incompatibility, but we can do it now.
189 # the case of having an ancestry is not very common, but arises in
191 unless ( $metaclass->isa( $ancestor_meta_class ) ) {
192 if ( $ancestor_meta_class->isa($metaclass) ) {
193 $metaclass = $ancestor_meta_class;
198 $meta = $metaclass->initialize($class);
201 unless ( $meta->has_method("meta") ) { # don't overwrite
202 # also check for inherited non moose 'meta' method?
203 # FIXME also skip this if the user requested by passing an option
206 # re-initialize so it inherits properly
207 $metaclass->initialize( ref($_[0]) || $_[0] );
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::Accessor
243 Moose::Meta::Method::Constructor
244 Moose::Meta::Method::Destructor
245 Moose::Meta::Method::Overridden
246 Moose::Meta::Method::Augmented
249 Moose::Meta::Role::Attribute
250 Moose::Meta::Role::Method
251 Moose::Meta::Role::Method::Required
252 Moose::Meta::Role::Method::Conflicting
254 Moose::Meta::Role::Composite
256 Moose::Meta::Role::Application
257 Moose::Meta::Role::Application::RoleSummation
258 Moose::Meta::Role::Application::ToClass
259 Moose::Meta::Role::Application::ToRole
260 Moose::Meta::Role::Application::ToInstance
263 Moose::Meta::Mixin::AttributeCore->meta->make_immutable(
264 inline_constructor => 0,
265 constructor_name => undef,
276 Moose - A postmodern object system for Perl 5
281 use Moose; # automatically turns on strict and warnings
283 has 'x' => (is => 'rw', isa => 'Int');
284 has 'y' => (is => 'rw', isa => 'Int');
297 has 'z' => (is => 'rw', isa => 'Int');
299 after 'clear' => sub {
306 Moose is an extension of the Perl 5 object system.
308 The main goal of Moose is to make Perl 5 Object Oriented programming
309 easier, more consistent and less tedious. With Moose you can to think
310 more about what you want to do and less about the mechanics of OOP.
312 Additionally, Moose is built on top of L<Class::MOP>, which is a
313 metaclass system for Perl 5. This means that Moose not only makes
314 building normal Perl 5 objects better, but it provides the power of
315 metaclass programming as well.
319 If you're new to Moose, the best place to start is the
320 L<Moose::Manual> docs, followed by the L<Moose::Cookbook>. The intro
321 will show you what Moose is, and how it makes Perl 5 OO better.
323 The cookbook recipes on Moose basics will get you up to speed with
324 many of Moose's features quickly. Once you have an idea of what Moose
325 can do, you can use the API documentation to get more detail on
326 features which interest you.
328 =head2 Moose Extensions
330 The C<MooseX::> namespace is the official place to find Moose extensions.
331 These extensions can be found on the CPAN. The easiest way to find them
332 is to search for them (L<http://search.cpan.org/search?query=MooseX::>),
333 or to examine L<Task::Moose> which aims to keep an up-to-date, easily
334 installable list of Moose extensions.
338 Much of the Moose documentation has been translated into other languages.
344 Japanese docs can be found at
345 L<http://perldoc.perlassociation.org/pod/Moose-Doc-JA/index.html>. The
346 source POD files can be found in GitHub:
347 L<http://github.com/jpa/Moose-Doc-JA>
351 =head1 BUILDING CLASSES WITH MOOSE
353 Moose makes every attempt to provide as much convenience as possible during
354 class construction/definition, but still stay out of your way if you want it
355 to. Here are a few items to note when building classes with Moose.
357 When you C<use Moose>, Moose will set the class's parent class to
358 L<Moose::Object>, I<unless> the class using Moose already has a parent
359 class. In addition, specifying a parent with C<extends> will change the parent
362 Moose will also manage all attributes (including inherited ones) that are
363 defined with C<has>. And (assuming you call C<new>, which is inherited from
364 L<Moose::Object>) this includes properly initializing all instance slots,
365 setting defaults where appropriate, and performing any type constraint checking
368 =head1 PROVIDED METHODS
370 Moose provides a number of methods to all your classes, mostly through the
371 inheritance of L<Moose::Object>. There is however, one exception.
377 This is a method which provides access to the current class's metaclass.
381 =head1 EXPORTED FUNCTIONS
383 Moose will export a number of functions into the class's namespace which
384 may then be used to set up the class. These functions all work directly
385 on the current class.
389 =item B<extends (@superclasses)>
391 This function will set the superclass(es) for the current class.
393 This approach is recommended instead of C<use base>, because C<use base>
394 actually C<push>es onto the class's C<@ISA>, whereas C<extends> will
395 replace it. This is important to ensure that classes which do not have
396 superclasses still properly inherit from L<Moose::Object>.
398 Each superclass can be followed by a hash reference with options. Currently,
399 only L<-version|Class::MOP/Class Loading Options> is recognized:
401 extends 'My::Parent' => { -version => 0.01 },
402 'My::OtherParent' => { -version => 0.03 };
404 An exception will be thrown if the version requirements are not
407 =item B<with (@roles)>
409 This will apply a given set of C<@roles> to the local class.
411 Like with C<extends>, each specified role can be followed by a hash
412 reference with a L<-version|Class::MOP/Class Loading Options> option:
414 with 'My::Role' => { -version => 0.32 },
415 'My::Otherrole' => { -version => 0.23 };
417 The specified version requirements must be satisfied, otherwise an
418 exception will be thrown.
420 If your role takes options or arguments, they can be passed along in the
421 hash reference as well.
423 =item B<has $name|@$names =E<gt> %options>
425 This will install an attribute of a given C<$name> into the current class. If
426 the first parameter is an array reference, it will create an attribute for
427 every C<$name> in the list. The C<%options> are the same as those provided by
428 L<Class::MOP::Attribute>, in addition to the list below which are provided by
429 Moose (L<Moose::Meta::Attribute> to be more specific):
433 =item I<is =E<gt> 'rw'|'ro'>
435 The I<is> option accepts either I<rw> (for read/write) or I<ro> (for read
436 only). These will create either a read/write accessor or a read-only
437 accessor respectively, using the same name as the C<$name> of the attribute.
439 If you need more control over how your accessors are named, you can
440 use the L<reader|Class::MOP::Attribute/reader>,
441 L<writer|Class::MOP::Attribute/writer> and
442 L<accessor|Class::MOP::Attribute/accessor> options inherited from
443 L<Class::MOP::Attribute>, however if you use those, you won't need the
446 =item I<isa =E<gt> $type_name>
448 The I<isa> option uses Moose's type constraint facilities to set up runtime
449 type checking for this attribute. Moose will perform the checks during class
450 construction, and within any accessors. The C<$type_name> argument must be a
451 string. The string may be either a class name or a type defined using
452 Moose's type definition features. (Refer to L<Moose::Util::TypeConstraints>
453 for information on how to define a new type, and how to retrieve type meta-data).
455 =item I<coerce =E<gt> (1|0)>
457 This will attempt to use coercion with the supplied type constraint to change
458 the value passed into any accessors or constructors. You B<must> supply a type
459 constraint, and that type constraint B<must> define a coercion. See
460 L<Moose::Cookbook::Basics::Recipe5> for an example.
462 =item I<does =E<gt> $role_name>
464 This will accept the name of a role which the value stored in this attribute
465 is expected to have consumed.
467 =item I<required =E<gt> (1|0)>
469 This marks the attribute as being required. This means a value must be
470 supplied during class construction, I<or> the attribute must be lazy
471 and have either a default or a builder. Note that c<required> does not
472 say anything about the attribute's value, which can be C<undef>.
474 =item I<weak_ref =E<gt> (1|0)>
476 This will tell the class to store the value of this attribute as a weakened
477 reference. If an attribute is a weakened reference, it B<cannot> also be
480 =item I<lazy =E<gt> (1|0)>
482 This will tell the class to not create this slot until absolutely necessary.
483 If an attribute is marked as lazy it B<must> have a default supplied.
485 =item I<auto_deref =E<gt> (1|0)>
487 This tells the accessor to automatically dereference the value of this
488 attribute when called in list context. The accessor will still return a
489 reference when called in scalar context. If this behavior isn't desirable,
490 L<Moose::Meta::Attribute::Native::Trait::Array/elements> or
491 L<Moose::Meta::Attribute::Native::Trait::Hash/elements> may be a better
492 choice. The I<auto_deref> option is only legal if your I<isa> option is
493 either C<ArrayRef> or C<HashRef>.
495 =item I<trigger =E<gt> $code>
497 The I<trigger> option is a CODE reference which will be called after
498 the value of the attribute is set. The CODE ref is passed the
499 instance itself, the updated value, and the original value if the
500 attribute was already set.
502 You B<can> have a trigger on a read-only attribute.
504 B<NOTE:> Triggers will only fire when you B<assign> to the attribute,
505 either in the constructor, or using the writer. Default and built values will
506 B<not> cause the trigger to be fired.
508 =item I<handles =E<gt> ARRAY | HASH | REGEXP | ROLE | ROLETYPE | DUCKTYPE | CODE>
510 The I<handles> option provides Moose classes with automated delegation features.
511 This is a pretty complex and powerful option. It accepts many different option
512 formats, each with its own benefits and drawbacks.
514 B<NOTE:> The class being delegated to does not need to be a Moose based class,
515 which is why this feature is especially useful when wrapping non-Moose classes.
517 All I<handles> option formats share the following traits:
519 You cannot override a locally defined method with a delegated method; an
520 exception will be thrown if you try. That is to say, if you define C<foo> in
521 your class, you cannot override it with a delegated C<foo>. This is almost never
522 something you would want to do, and if it is, you should do it by hand and not
525 You cannot override any of the methods found in Moose::Object, or the C<BUILD>
526 and C<DEMOLISH> methods. These will not throw an exception, but will silently
527 move on to the next method in the list. My reasoning for this is that you would
528 almost never want to do this, since it usually breaks your class. As with
529 overriding locally defined methods, if you do want to do this, you should do it
530 manually, not with Moose.
532 You do not I<need> to have a reader (or accessor) for the attribute in order
533 to delegate to it. Moose will create a means of accessing the value for you,
534 however this will be several times B<less> efficient then if you had given
535 the attribute a reader (or accessor) to use.
537 Below is the documentation for each option format:
543 This is the most common usage for I<handles>. You basically pass a list of
544 method names to be delegated, and Moose will install a delegation method
549 This is the second most common usage for I<handles>. Instead of a list of
550 method names, you pass a HASH ref where each key is the method name you
551 want installed locally, and its value is the name of the original method
552 in the class being delegated to.
554 This can be very useful for recursive classes like trees. Here is a
555 quick example (soon to be expanded into a Moose::Cookbook recipe):
560 has 'node' => (is => 'rw', isa => 'Any');
565 default => sub { [] }
573 parent_node => 'node',
574 siblings => 'children',
578 In this example, the Tree package gets C<parent_node> and C<siblings> methods,
579 which delegate to the C<node> and C<children> methods (respectively) of the Tree
580 instance stored in the C<parent> slot.
582 You may also use an array reference to curry arguments to the original method.
586 handles => { set_foo => [ set => 'foo' ] },
589 # $self->set_foo(...) calls $self->thing->set('foo', ...)
591 The first element of the array reference is the original method name, and the
592 rest is a list of curried arguments.
596 The regexp option works very similar to the ARRAY option, except that it builds
597 the list of methods for you. It starts by collecting all possible methods of the
598 class being delegated to, then filters that list using the regexp supplied here.
600 B<NOTE:> An I<isa> option is required when using the regexp option format. This
601 is so that we can determine (at compile time) the method list from the class.
602 Without an I<isa> this is just not possible.
604 =item C<ROLE> or C<ROLETYPE>
606 With the role option, you specify the name of a role or a
607 L<role type|Moose::Meta::TypeConstraint::Role> whose "interface" then becomes
608 the list of methods to handle. The "interface" can be defined as; the methods
609 of the role and any required methods of the role. It should be noted that this
610 does B<not> include any method modifiers or generated attribute methods (which
611 is consistent with role composition).
615 With the duck type option, you pass a duck type object whose "interface" then
616 becomes the list of methods to handle. The "interface" can be defined as; the
617 list of methods passed to C<duck_type> to create a duck type object. For more
618 information on C<duck_type> please check
619 L<Moose::Util::TypeConstraints>.
623 This is the option to use when you really want to do something funky. You should
624 only use it if you really know what you are doing, as it involves manual
627 This takes a code reference, which should expect two arguments. The first is the
628 attribute meta-object this I<handles> is attached to. The second is the
629 metaclass of the class being delegated to. It expects you to return a hash (not
630 a HASH ref) of the methods you want mapped.
634 =item I<metaclass =E<gt> $metaclass_name>
636 This tells the class to use a custom attribute metaclass for this particular
637 attribute. Custom attribute metaclasses are useful for extending the
638 capabilities of the I<has> keyword: they are the simplest way to extend the MOP,
639 but they are still a fairly advanced topic and too much to cover here, see
640 L<Moose::Cookbook::Meta::Recipe1> for more information.
642 See L<Metaclass and Trait Name Resolution> for details on how a metaclass name
643 is resolved to a class name.
645 =item I<traits =E<gt> [ @role_names ]>
647 This tells Moose to take the list of C<@role_names> and apply them to the
648 attribute meta-object. This is very similar to the I<metaclass> option, but
649 allows you to use more than one extension at a time.
651 See L<Metaclass and Trait Name Resolution> for details on how a trait name is
652 resolved to a role name.
654 Also see L<Moose::Cookbook::Meta::Recipe3> for a metaclass trait
657 =item I<builder> => Str
659 The value of this key is the name of the method that will be called to
660 obtain the value used to initialize the attribute. See the L<builder
661 option docs in Class::MOP::Attribute|Class::MOP::Attribute/builder>
662 and/or L<Moose::Cookbook::Basics::Recipe8> for more information.
664 =item I<default> => SCALAR | CODE
666 The value of this key is the default value which will initialize the attribute.
668 NOTE: If the value is a simple scalar (string or number), then it can
669 be just passed as is. However, if you wish to initialize it with a
670 HASH or ARRAY ref, then you need to wrap that inside a CODE reference.
671 See the L<default option docs in
672 Class::MOP::Attribute|Class::MOP::Attribute/default> for more
675 =item I<clearer> => Str
677 Creates a method allowing you to clear the value, see the L<clearer option
678 docs in Class::MOP::Attribute|Class::MOP::Attribute/clearer> for more
681 =item I<predicate> => Str
683 Creates a method to perform a basic test to see if a value has been set in the
684 attribute, see the L<predicate option docs in
685 Class::MOP::Attribute|Class::MOP::Attribute/predicate> for more information.
687 =item I<lazy_build> => (0|1)
689 Automatically define lazy => 1 as well as builder => "_build_$attr", clearer =>
690 "clear_$attr', predicate => 'has_$attr' unless they are already defined.
692 =item I<initializer> => Str
694 This may be a method name (referring to a method on the class with
695 this attribute) or a CODE ref. The initializer is used to set the
696 attribute value on an instance when the attribute is set during
697 instance initialization (but not when the value is being assigned
698 to). See the L<initializer option docs in
699 Class::MOP::Attribute|Class::MOP::Attribute/initializer> for more
702 =item I<documentation> => $string
704 An arbitrary string that can be retrieved later by calling C<<
705 $attr->documentation >>.
711 =item B<has +$name =E<gt> %options>
713 This is variation on the normal attribute creator C<has> which allows you to
714 clone and extend an attribute from a superclass or from a role. Here is an
715 example of the superclass usage:
723 default => 'Hello, I am a Foo'
731 has '+message' => (default => 'Hello I am My::Foo');
733 What is happening here is that B<My::Foo> is cloning the C<message> attribute
734 from its parent class B<Foo>, retaining the C<is =E<gt> 'rw'> and C<isa =E<gt>
735 'Str'> characteristics, but changing the value in C<default>.
737 Here is another example, but within the context of a role:
745 default => 'Hello, I am a Foo'
753 has '+message' => (default => 'Hello I am My::Foo');
755 In this case, we are basically taking the attribute which the role supplied
756 and altering it within the bounds of this feature.
758 Note that you can only extend an attribute from either a superclass or a role,
759 you cannot extend an attribute in a role that composes over an attribute from
762 Aside from where the attributes come from (one from superclass, the other
763 from a role), this feature works exactly the same. This feature is restricted
764 somewhat, so as to try and force at least I<some> sanity into it. You are only
765 allowed to change the following attributes:
771 Change the default value of an attribute.
775 Change whether the attribute attempts to coerce a value passed to it.
779 Change if the attribute is required to have a value.
781 =item I<documentation>
783 Change the documentation string associated with the attribute.
787 Change if the attribute lazily initializes the slot.
791 You I<are> allowed to change the type without restriction.
793 It is recommended that you use this freedom with caution. We used to
794 only allow for extension only if the type was a subtype of the parent's
795 type, but we felt that was too restrictive and is better left as a
800 You are allowed to B<add> a new C<handles> definition, but you are B<not>
801 allowed to I<change> one.
805 You are allowed to B<add> a new C<builder> definition, but you are B<not>
806 allowed to I<change> one.
810 You are allowed to B<add> a new C<metaclass> definition, but you are
811 B<not> allowed to I<change> one.
815 You are allowed to B<add> additional traits to the C<traits> definition.
816 These traits will be composed into the attribute, but preexisting traits
817 B<are not> overridden, or removed.
821 =item B<before $name|@names|\@names|qr/.../ =E<gt> sub { ... }>
823 =item B<after $name|@names|\@names|qr/.../ =E<gt> sub { ... }>
825 =item B<around $name|@names|\@names|qr/.../ =E<gt> sub { ... }>
827 These three items are syntactic sugar for the before, after, and around method
828 modifier features that L<Class::MOP> provides. More information on these may be
829 found in L<Moose::Manual::MethodModifiers> and the
830 L<Class::MOP::Class documentation|Class::MOP::Class/"Method Modifiers">.
834 The keyword C<super> is a no-op when called outside of an C<override> method. In
835 the context of an C<override> method, it will call the next most appropriate
836 superclass method with the same arguments as the original method.
838 =item B<override ($name, &sub)>
840 An C<override> method is a way of explicitly saying "I am overriding this
841 method from my superclass". You can call C<super> within this method, and
842 it will work as expected. The same thing I<can> be accomplished with a normal
843 method call and the C<SUPER::> pseudo-package; it is really your choice.
847 The keyword C<inner>, much like C<super>, is a no-op outside of the context of
848 an C<augment> method. You can think of C<inner> as being the inverse of
849 C<super>; the details of how C<inner> and C<augment> work is best described in
850 the L<Moose::Cookbook::Basics::Recipe6>.
852 =item B<augment ($name, &sub)>
854 An C<augment> method, is a way of explicitly saying "I am augmenting this
855 method from my superclass". Once again, the details of how C<inner> and
856 C<augment> work is best described in the L<Moose::Cookbook::Basics::Recipe6>.
860 This is the C<Carp::confess> function, and exported here because I use it
865 This is the C<Scalar::Util::blessed> function, it is exported here because I
866 use it all the time. It is highly recommended that this is used instead of
867 C<ref> anywhere you need to test for an object's class name.
873 When you use Moose, you can specify which metaclass to use:
875 use Moose -metaclass => 'My::Meta::Class';
877 You can also specify traits which will be applied to your metaclass:
879 use Moose -traits => 'My::Trait';
881 This is very similar to the attribute traits feature. When you do
882 this, your class's C<meta> object will have the specified traits
883 applied to it. See L<Metaclass and Trait Name Resolution> for more
886 =head2 Metaclass and Trait Name Resolution
888 By default, when given a trait name, Moose simply tries to load a
889 class of the same name. If such a class does not exist, it then looks
890 for for a class matching
891 B<Moose::Meta::$type::Custom::Trait::$trait_name>. The C<$type>
892 variable here will be one of B<Attribute> or B<Class>, depending on
893 what the trait is being applied to.
895 If a class with this long name exists, Moose checks to see if it has
896 the method C<register_implementation>. This method is expected to
897 return the I<real> class name of the trait. If there is no
898 C<register_implementation> method, it will fall back to using
899 B<Moose::Meta::$type::Custom::Trait::$trait> as the trait name.
901 The lookup method for metaclasses is the same, except that it looks
902 for a class matching B<Moose::Meta::$type::Custom::$metaclass_name>.
904 If all this is confusing, take a look at
905 L<Moose::Cookbook::Meta::Recipe3>, which demonstrates how to create an
908 =head1 UNIMPORTING FUNCTIONS
912 Moose offers a way to remove the keywords it exports, through the C<unimport>
913 method. You simply have to say C<no Moose> at the bottom of your code for this
914 to work. Here is an example:
919 has 'first_name' => (is => 'rw', isa => 'Str');
920 has 'last_name' => (is => 'rw', isa => 'Str');
924 $self->first_name . ' ' . $self->last_name
927 no Moose; # keywords are removed from the Person package
929 =head1 EXTENDING AND EMBEDDING MOOSE
931 To learn more about extending Moose, we recommend checking out the
932 "Extending" recipes in the L<Moose::Cookbook>, starting with
933 L<Moose::Cookbook::Extending::Recipe1>, which provides an overview of
934 all the different ways you might extend Moose.
936 =head2 B<< Moose->init_meta(for_class => $class, base_class => $baseclass, metaclass => $metaclass) >>
938 The C<init_meta> method sets up the metaclass object for the class
939 specified by C<for_class>. This method injects a a C<meta> accessor
940 into the class so you can get at this object. It also sets the class's
941 superclass to C<base_class>, with L<Moose::Object> as the default.
943 C<init_meta> returns the metaclass object for C<$class>.
945 You can specify an alternate metaclass with the C<metaclass> option.
947 For more detail on this topic, see L<Moose::Cookbook::Extending::Recipe2>.
949 This method used to be documented as a function which accepted
950 positional parameters. This calling style will still work for
951 backwards compatibility, but is deprecated.
955 Moose's C<import> method supports the L<Sub::Exporter> form of C<{into =E<gt> $pkg}>
956 and C<{into_level =E<gt> 1}>.
958 B<NOTE>: Doing this is more or less deprecated. Use L<Moose::Exporter>
959 instead, which lets you stack multiple C<Moose.pm>-alike modules
960 sanely. It handles getting the exported functions into the right place
963 =head2 B<throw_error>
965 An alias for C<confess>, used by internally by Moose.
967 =head2 The MooseX:: namespace
969 Generally if you're writing an extension I<for> Moose itself you'll want
970 to put your extension in the C<MooseX::> namespace. This namespace is
971 specifically for extensions that make Moose better or different in some
972 fundamental way. It is traditionally B<not> for a package that just happens
973 to use Moose. This namespace follows from the examples of the C<LWPx::>
974 and C<DBIx::> namespaces that perform the same function for C<LWP> and C<DBI>
977 =head1 METACLASS COMPATIBILITY AND MOOSE
979 Metaclass compatibility is a thorny subject. You should start by
980 reading the "About Metaclass compatibility" section in the
983 Moose will attempt to resolve a few cases of metaclass incompatibility
984 when you set the superclasses for a class, in addition to the cases that
985 C<Class::MOP> handles.
987 Moose tries to determine if the metaclasses only "differ by roles". This
988 means that the parent and child's metaclass share a common ancestor in
989 their respective hierarchies, and that the subclasses under the common
990 ancestor are only different because of role applications. This case is
991 actually fairly common when you mix and match various C<MooseX::*>
992 modules, many of which apply roles to the metaclass.
994 If the parent and child do differ by roles, Moose replaces the
995 metaclass in the child with a newly created metaclass. This metaclass
996 is a subclass of the parent's metaclass, does all of the roles that
997 the child's metaclass did before being replaced. Effectively, this
998 means the new metaclass does all of the roles done by both the
999 parent's and child's original metaclasses.
1001 Ultimately, this is all transparent to you except in the case of an
1002 unresolvable conflict.
1010 It should be noted that C<super> and C<inner> B<cannot> be used in the same
1011 method. However, they may be combined within the same class hierarchy; see
1012 F<t/014_override_augment_inner_super.t> for an example.
1014 The reason for this is that C<super> is only valid within a method
1015 with the C<override> modifier, and C<inner> will never be valid within an
1016 C<override> method. In fact, C<augment> will skip over any C<override> methods
1017 when searching for its appropriate C<inner>.
1019 This might seem like a restriction, but I am of the opinion that keeping these
1020 two features separate (yet interoperable) actually makes them easy to use, since
1021 their behavior is then easier to predict. Time will tell whether I am right or
1022 not (UPDATE: so far so good).
1028 We offer both a mailing list and a very active IRC channel.
1030 The mailing list is L<moose@perl.org>. You must be subscribed to send
1031 a message. To subscribe, send an empty message to
1032 L<moose-subscribe@perl.org>
1034 You can also visit us at C<#moose> on L<irc://irc.perl.org/#moose>
1035 This channel is quite active, and questions at all levels (on Moose-related
1036 topics ;) are welcome.
1038 =head1 ACKNOWLEDGEMENTS
1042 =item I blame Sam Vilain for introducing me to the insanity that is meta-models.
1044 =item I blame Audrey Tang for then encouraging my meta-model habit in #perl6.
1046 =item Without Yuval "nothingmuch" Kogman this module would not be possible,
1047 and it certainly wouldn't have this name ;P
1049 =item The basis of the TypeContraints module was Rob Kinyon's idea
1050 originally, I just ran with it.
1052 =item Thanks to mst & chansen and the whole #moose posse for all the
1053 early ideas/feature-requests/encouragement/bug-finding.
1055 =item Thanks to David "Theory" Wheeler for meta-discussions and spelling fixes.
1063 =item L<http://www.iinteractive.com/moose>
1065 This is the official web home of Moose, it contains links to our public git repository
1066 as well as links to a number of talks and articles on Moose and Moose related
1069 =item The Moose is flying, a tutorial by Randal Schwartz
1071 Part 1 - L<http://www.stonehenge.com/merlyn/LinuxMag/col94.html>
1073 Part 2 - L<http://www.stonehenge.com/merlyn/LinuxMag/col95.html>
1075 =item Several Moose extension modules in the C<MooseX::> namespace.
1077 See L<http://search.cpan.org/search?query=MooseX::> for extensions.
1079 =item Moose stats on ohloh.net - L<http://www.ohloh.net/projects/moose>
1087 =item The Art of the MetaObject Protocol
1089 I mention this in the L<Class::MOP> docs too, this book was critical in
1090 the development of both modules and is highly recommended.
1098 =item L<http://www.cs.utah.edu/plt/publications/oopsla04-gff.pdf>
1100 This paper (suggested by lbr on #moose) was what lead to the implementation
1101 of the C<super>/C<override> and C<inner>/C<augment> features. If you really
1102 want to understand them, I suggest you read this.
1108 All complex software has bugs lurking in it, and this module is no
1111 Please report any bugs to C<bug-moose@rt.cpan.org>, or through the web
1112 interface at L<http://rt.cpan.org>.
1114 You can also discuss feature requests or possible bugs on the Moose mailing
1115 list (moose@perl.org) or on IRC at L<irc://irc.perl.org/#moose>.
1117 =head1 FEATURE REQUESTS
1119 We are very strict about what features we add to the Moose core, especially
1120 the user-visible features. Instead we have made sure that the underlying
1121 meta-system of Moose is as extensible as possible so that you can add your
1122 own features easily.
1124 That said, occasionally there is a feature needed in the meta-system
1125 to support your planned extension, in which case you should either
1126 email the mailing list (moose@perl.org) or join us on IRC at
1127 L<irc://irc.perl.org/#moose> to discuss. The
1128 L<Moose::Manual::Contributing> has more detail about how and when you
1133 Moose is an open project, there are at this point dozens of people who have
1134 contributed, and can contribute. If you have added anything to the Moose
1135 project you have a commit bit on this file and can add your name to the list.
1139 However there are only a few people with the rights to release a new version
1140 of Moose. The Moose Cabal are the people to go to with questions regarding
1141 the wider purview of Moose, and help out maintaining not just the code
1142 but the community as well.
1144 Stevan (stevan) Little E<lt>stevan@iinteractive.comE<gt>
1146 Jesse (doy) Luehrs E<lt>doy at tozt dot netE<gt>
1148 Yuval (nothingmuch) Kogman
1150 Shawn (sartak) Moore E<lt>sartak@bestpractical.comE<gt>
1152 Hans Dieter (confound) Pearcey E<lt>hdp@pobox.comE<gt>
1154 Chris (perigrin) Prather
1156 Florian Ragwitz E<lt>rafl@debian.orgE<gt>
1158 Dave (autarch) Rolsky E<lt>autarch@urth.orgE<gt>
1160 =head2 OTHER CONTRIBUTORS
1164 Adam (Alias) Kennedy
1166 Anders (Debolaz) Nor Berle
1168 Nathan (kolibrie) Gray
1170 Christian (chansen) Hansen
1172 Eric (ewilhelm) Wilhelm
1174 Guillermo (groditi) Roditi
1176 Jess (castaway) Robinson
1180 Robert (phaylon) Sedlacek
1184 Scott (konobi) McWhirter
1186 Shlomi (rindolf) Fish
1188 Wallace (wreis) Reis
1190 Jonathan (jrockway) Rockway
1192 Piotr (dexter) Roszatycki
1194 Sam (mugwump) Vilain
1198 Dylan Hardison (doc fixes)
1200 ... and many other #moose folks
1202 =head1 COPYRIGHT AND LICENSE
1204 Copyright 2006-2010 by Infinity Interactive, Inc.
1206 L<http://www.iinteractive.com>
1208 This library is free software; you can redistribute it and/or modify
1209 it under the same terms as Perl itself.