8 $VERSION = eval $VERSION;
9 our $AUTHORITY = 'cpan:STEVAN';
11 use Scalar::Util 'blessed';
18 use Moose::Meta::Class;
19 use Moose::Meta::TypeConstraint;
20 use Moose::Meta::TypeCoercion;
21 use Moose::Meta::Attribute;
22 use Moose::Meta::Instance;
26 use Moose::Meta::Role;
27 use Moose::Meta::Role::Composite;
28 use Moose::Meta::Role::Application;
29 use Moose::Meta::Role::Application::RoleSummation;
30 use Moose::Meta::Role::Application::ToClass;
31 use Moose::Meta::Role::Application::ToRole;
32 use Moose::Meta::Role::Application::ToInstance;
34 use Moose::Util::TypeConstraints;
37 use Moose::Meta::Attribute::Native;
48 Moose->throw_error("Must derive at least one class") unless @_;
50 # this checks the metaclass to make sure
51 # it is correct, sometimes it can get out
52 # of sync when the classes are being built
53 $meta->superclasses(@_);
57 Moose::Util::apply_all_roles(shift, @_);
64 Moose->throw_error('Usage: has \'name\' => ( key => value, ... )')
67 my %options = ( definition_context => Moose::Util::_caller_info(), @_ );
68 my $attrs = ( ref($name) eq 'ARRAY' ) ? $name : [ ($name) ];
69 $meta->add_attribute( $_, %options ) for @$attrs;
73 Moose::Util::add_method_modifier(shift, 'before', \@_);
77 Moose::Util::add_method_modifier(shift, 'after', \@_);
81 Moose::Util::add_method_modifier(shift, 'around', \@_);
89 # This check avoids a recursion loop - see
90 # t/100_bugs/020_super_recursion.t
91 return if defined $SUPER_PACKAGE && $SUPER_PACKAGE ne caller();
92 return unless $SUPER_BODY; $SUPER_BODY->(@SUPER_ARGS);
97 my ( $name, $method ) = @_;
98 $meta->add_override_method_modifier( $name => $method );
103 our ( %INNER_BODY, %INNER_ARGS );
105 if ( my $body = $INNER_BODY{$pkg} ) {
106 my @args = @{ $INNER_ARGS{$pkg} };
107 local $INNER_ARGS{$pkg};
108 local $INNER_BODY{$pkg};
109 return $body->(@args);
117 my ( $name, $method ) = @_;
118 $meta->add_augment_method_modifier( $name => $method );
121 Moose::Exporter->setup_import_methods(
123 qw( extends with has before after around override augment )
128 \&Scalar::Util::blessed,
133 # This used to be called as a function. This hack preserves
134 # backwards compatibility.
135 if ( $_[0] ne __PACKAGE__ ) {
136 return __PACKAGE__->init_meta(
146 my $class = $args{for_class}
147 or Moose->throw_error("Cannot call init_meta without specifying a for_class");
148 my $base_class = $args{base_class} || 'Moose::Object';
149 my $metaclass = $args{metaclass} || 'Moose::Meta::Class';
151 Moose->throw_error("The Metaclass $metaclass must be a subclass of Moose::Meta::Class.")
152 unless $metaclass->isa('Moose::Meta::Class');
154 # make a subtype for each Moose class
156 unless find_type_constraint($class);
160 if ( $meta = Class::MOP::get_metaclass_by_name($class) ) {
161 unless ( $meta->isa("Moose::Meta::Class") ) {
162 my $error_message = "$class already has a metaclass, but it does not inherit $metaclass ($meta).";
163 if ( $meta->isa('Moose::Meta::Role') ) {
164 Moose->throw_error($error_message . ' You cannot make the same thing a role and a class. Remove either Moose or Moose::Role.');
166 Moose->throw_error($error_message);
170 # no metaclass, no 'meta' method
172 # now we check whether our ancestors have metaclass, and if so borrow that
173 my ( undef, @isa ) = @{ $class->mro::get_linear_isa };
175 foreach my $ancestor ( @isa ) {
176 my $ancestor_meta = Class::MOP::get_metaclass_by_name($ancestor) || next;
178 my $ancestor_meta_class = ($ancestor_meta->is_immutable
179 ? $ancestor_meta->_get_mutable_metaclass_name
180 : ref($ancestor_meta));
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 ( $class->can('meta') ) {
198 # check 'meta' method
200 # it may be inherited
203 # this is the case where the metaclass pragma
204 # was used before the 'use Moose' statement to
205 # override a specific class
206 my $method_meta = $class->meta;
208 ( blessed($method_meta) && $method_meta->isa('Moose::Meta::Class') )
209 || Moose->throw_error("$class already has a &meta function, but it does not return a Moose::Meta::Class ($method_meta)");
211 $meta = $method_meta;
214 unless ( $meta->has_method("meta") ) { # don't overwrite
215 # also check for inherited non moose 'meta' method?
216 # FIXME also skip this if the user requested by passing an option
219 # re-initialize so it inherits properly
220 $metaclass->initialize( ref($_[0]) || $_[0] );
225 # make sure they inherit from Moose::Object
226 $meta->superclasses($base_class)
227 unless $meta->superclasses();
232 # This may be used in some older MooseX extensions.
234 goto &Moose::Exporter::_get_caller;
237 ## make 'em all immutable
240 inline_constructor => 1,
241 constructor_name => "_new",
242 # these are Class::MOP accessors, so they need inlining
243 inline_accessors => 1
244 ) for grep { $_->is_mutable }
247 Moose::Meta::Attribute
249 Moose::Meta::Instance
251 Moose::Meta::TypeCoercion
252 Moose::Meta::TypeCoercion::Union
255 Moose::Meta::Method::Accessor
256 Moose::Meta::Method::Constructor
257 Moose::Meta::Method::Destructor
258 Moose::Meta::Method::Overridden
259 Moose::Meta::Method::Augmented
262 Moose::Meta::Role::Attribute
263 Moose::Meta::Role::Method
264 Moose::Meta::Role::Method::Required
265 Moose::Meta::Role::Method::Conflicting
267 Moose::Meta::Role::Composite
269 Moose::Meta::Role::Application
270 Moose::Meta::Role::Application::RoleSummation
271 Moose::Meta::Role::Application::ToClass
272 Moose::Meta::Role::Application::ToRole
273 Moose::Meta::Role::Application::ToInstance
276 Moose::Meta::Mixin::AttributeCore->meta->make_immutable(
277 inline_constructor => 0,
278 constructor_name => undef,
289 Moose - A postmodern object system for Perl 5
294 use Moose; # automatically turns on strict and warnings
296 has 'x' => (is => 'rw', isa => 'Int');
297 has 'y' => (is => 'rw', isa => 'Int');
310 has 'z' => (is => 'rw', isa => 'Int');
312 after 'clear' => sub {
319 Moose is an extension of the Perl 5 object system.
321 The main goal of Moose is to make Perl 5 Object Oriented programming
322 easier, more consistent and less tedious. With Moose you can to think
323 more about what you want to do and less about the mechanics of OOP.
325 Additionally, Moose is built on top of L<Class::MOP>, which is a
326 metaclass system for Perl 5. This means that Moose not only makes
327 building normal Perl 5 objects better, but it provides the power of
328 metaclass programming as well.
332 If you're new to Moose, the best place to start is the
333 L<Moose::Manual> docs, followed by the L<Moose::Cookbook>. The intro
334 will show you what Moose is, and how it makes Perl 5 OO better.
336 The cookbook recipes on Moose basics will get you up to speed with
337 many of Moose's features quickly. Once you have an idea of what Moose
338 can do, you can use the API documentation to get more detail on
339 features which interest you.
341 =head2 Moose Extensions
343 The C<MooseX::> namespace is the official place to find Moose extensions.
344 These extensions can be found on the CPAN. The easiest way to find them
345 is to search for them (L<http://search.cpan.org/search?query=MooseX::>),
346 or to examine L<Task::Moose> which aims to keep an up-to-date, easily
347 installable list of Moose extensions.
351 Much of the Moose documentation has been translated into other languages.
357 Japanese docs can be found at L<http://perldoc.perlassociation.org/pod/Moose-Doc-JA/index.html>. The source POD files can be found in GitHub: L<http://github.com/jpa/Moose-Doc-JA>
361 =head1 BUILDING CLASSES WITH MOOSE
363 Moose makes every attempt to provide as much convenience as possible during
364 class construction/definition, but still stay out of your way if you want it
365 to. Here are a few items to note when building classes with Moose.
367 Unless specified with C<extends>, any class which uses Moose will
368 inherit from L<Moose::Object>.
370 Moose will also manage all attributes (including inherited ones) that are
371 defined with C<has>. And (assuming you call C<new>, which is inherited from
372 L<Moose::Object>) this includes properly initializing all instance slots,
373 setting defaults where appropriate, and performing any type constraint checking
376 =head1 PROVIDED METHODS
378 Moose provides a number of methods to all your classes, mostly through the
379 inheritance of L<Moose::Object>. There is however, one exception.
385 This is a method which provides access to the current class's metaclass.
389 =head1 EXPORTED FUNCTIONS
391 Moose will export a number of functions into the class's namespace which
392 may then be used to set up the class. These functions all work directly
393 on the current class.
397 =item B<extends (@superclasses)>
399 This function will set the superclass(es) for the current class.
401 This approach is recommended instead of C<use base>, because C<use base>
402 actually C<push>es onto the class's C<@ISA>, whereas C<extends> will
403 replace it. This is important to ensure that classes which do not have
404 superclasses still properly inherit from L<Moose::Object>.
406 Each superclass can be followed by a hash reference with options. Currently,
407 only L<-version|Class::MOP/Class Loading Options> is recognized:
409 extends 'My::Parent' => { -version => 0.01 },
410 'My::OtherParent' => { -version => 0.03 };
412 An exception will be thrown if the version requirements are not
415 =item B<with (@roles)>
417 This will apply a given set of C<@roles> to the local class.
419 Like with C<extends>, each specified role can be followed by a hash
420 reference with a L<-version|Class::MOP/Class Loading Options> option:
422 with 'My::Role' => { -version => 0.32 },
423 'My::Otherrole' => { -version => 0.23 };
425 The specified version requirements must be satisfied, otherwise an
426 exception will be thrown.
428 If your role takes options or arguments, they can be passed along in the
429 hash reference as well.
431 =item B<has $name|@$names =E<gt> %options>
433 This will install an attribute of a given C<$name> into the current class. If
434 the first parameter is an array reference, it will create an attribute for
435 every C<$name> in the list. The C<%options> are the same as those provided by
436 L<Class::MOP::Attribute>, in addition to the list below which are provided by
437 Moose (L<Moose::Meta::Attribute> to be more specific):
441 =item I<is =E<gt> 'rw'|'ro'>
443 The I<is> option accepts either I<rw> (for read/write) or I<ro> (for read
444 only). These will create either a read/write accessor or a read-only
445 accessor respectively, using the same name as the C<$name> of the attribute.
447 If you need more control over how your accessors are named, you can
448 use the L<reader|Class::MOP::Attribute/reader>,
449 L<writer|Class::MOP::Attribute/writer> and
450 L<accessor|Class::MOP::Attribute/accessor> options inherited from
451 L<Class::MOP::Attribute>, however if you use those, you won't need the
454 =item I<isa =E<gt> $type_name>
456 The I<isa> option uses Moose's type constraint facilities to set up runtime
457 type checking for this attribute. Moose will perform the checks during class
458 construction, and within any accessors. The C<$type_name> argument must be a
459 string. The string may be either a class name or a type defined using
460 Moose's type definition features. (Refer to L<Moose::Util::TypeConstraints>
461 for information on how to define a new type, and how to retrieve type meta-data).
463 =item I<coerce =E<gt> (1|0)>
465 This will attempt to use coercion with the supplied type constraint to change
466 the value passed into any accessors or constructors. You B<must> have supplied
467 a type constraint in order for this to work. See L<Moose::Cookbook::Basics::Recipe5>
470 =item I<does =E<gt> $role_name>
472 This will accept the name of a role which the value stored in this attribute
473 is expected to have consumed.
475 =item I<required =E<gt> (1|0)>
477 This marks the attribute as being required. This means a value must be
478 supplied during class construction, I<or> the attribute must be lazy
479 and have either a default or a builder. Note that c<required> does not
480 say anything about the attribute's value, which can be C<undef>.
482 =item I<weak_ref =E<gt> (1|0)>
484 This will tell the class to store the value of this attribute as a weakened
485 reference. If an attribute is a weakened reference, it B<cannot> also be
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 supplied.
493 =item I<auto_deref =E<gt> (1|0)>
495 This tells the accessor to automatically dereference the value of this
496 attribute when called in list context. The accessor will still return a
497 reference when called in scalar context. If this behavior isn't desirable,
498 L<Moose::Meta::Attribute::Native::Trait::Array/elements> or
499 L<Moose::Meta::Attribute::Native::Trait::Hash/elements> may be a better
500 choice. The I<auto_deref> option is only legal if your I<isa> option is
501 either C<ArrayRef> or C<HashRef>.
503 =item I<trigger =E<gt> $code>
505 The I<trigger> option is a CODE reference which will be called after
506 the value of the attribute is set. The CODE ref is passed the
507 instance itself, the updated value, and the original value if the
508 attribute was already set.
510 You B<can> have a trigger on a read-only attribute.
512 B<NOTE:> Triggers will only fire when you B<assign> to the attribute,
513 either in the constructor, or using the writer. Default and built values will
514 B<not> cause the trigger to be fired.
516 =item I<handles =E<gt> ARRAY | HASH | REGEXP | ROLE | ROLETYPE | DUCKTYPE | CODE>
518 The I<handles> option provides Moose classes with automated delegation features.
519 This is a pretty complex and powerful option. It accepts many different option
520 formats, each with its own benefits and drawbacks.
522 B<NOTE:> The class being delegated to does not need to be a Moose based class,
523 which is why this feature is especially useful when wrapping non-Moose classes.
525 All I<handles> option formats share the following traits:
527 You cannot override a locally defined method with a delegated method; an
528 exception will be thrown if you try. That is to say, if you define C<foo> in
529 your class, you cannot override it with a delegated C<foo>. This is almost never
530 something you would want to do, and if it is, you should do it by hand and not
533 You cannot override any of the methods found in Moose::Object, or the C<BUILD>
534 and C<DEMOLISH> methods. These will not throw an exception, but will silently
535 move on to the next method in the list. My reasoning for this is that you would
536 almost never want to do this, since it usually breaks your class. As with
537 overriding locally defined methods, if you do want to do this, you should do it
538 manually, not with Moose.
540 You do not I<need> to have a reader (or accessor) for the attribute in order
541 to delegate to it. Moose will create a means of accessing the value for you,
542 however this will be several times B<less> efficient then if you had given
543 the attribute a reader (or accessor) to use.
545 Below is the documentation for each option format:
551 This is the most common usage for I<handles>. You basically pass a list of
552 method names to be delegated, and Moose will install a delegation method
557 This is the second most common usage for I<handles>. Instead of a list of
558 method names, you pass a HASH ref where each key is the method name you
559 want installed locally, and its value is the name of the original method
560 in the class being delegated to.
562 This can be very useful for recursive classes like trees. Here is a
563 quick example (soon to be expanded into a Moose::Cookbook recipe):
568 has 'node' => (is => 'rw', isa => 'Any');
573 default => sub { [] }
581 parent_node => 'node',
582 siblings => 'children',
586 In this example, the Tree package gets C<parent_node> and C<siblings> methods,
587 which delegate to the C<node> and C<children> methods (respectively) of the Tree
588 instance stored in the C<parent> slot.
590 You may also use an array reference to curry arguments to the original method.
594 handles => { set_foo => [ set => 'foo' ] },
597 # $self->set_foo(...) calls $self->thing->set('foo', ...)
599 The first element of the array reference is the original method name, and the
600 rest is a list of curried arguments.
604 The regexp option works very similar to the ARRAY option, except that it builds
605 the list of methods for you. It starts by collecting all possible methods of the
606 class being delegated to, then filters that list using the regexp supplied here.
608 B<NOTE:> An I<isa> option is required when using the regexp option format. This
609 is so that we can determine (at compile time) the method list from the class.
610 Without an I<isa> this is just not possible.
612 =item C<ROLE> or C<ROLETYPE>
614 With the role option, you specify the name of a role or a
615 L<role type|Moose::Meta::TypeConstraint::Role> whose "interface" then becomes
616 the list of methods to handle. The "interface" can be defined as; the methods
617 of the role and any required methods of the role. It should be noted that this
618 does B<not> include any method modifiers or generated attribute methods (which
619 is consistent with role composition).
623 With the duck type option, you pass a duck type object whose "interface" then
624 becomes the list of methods to handle. The "interface" can be defined as; the
625 list of methods passed to C<duck_type> to create a duck type object. For more
626 information on C<duck_type> please check
627 L<Moose::Util::TypeConstraints>.
631 This is the option to use when you really want to do something funky. You should
632 only use it if you really know what you are doing, as it involves manual
635 This takes a code reference, which should expect two arguments. The first is the
636 attribute meta-object this I<handles> is attached to. The second is the
637 metaclass of the class being delegated to. It expects you to return a hash (not
638 a HASH ref) of the methods you want mapped.
642 =item I<metaclass =E<gt> $metaclass_name>
644 This tells the class to use a custom attribute metaclass for this particular
645 attribute. Custom attribute metaclasses are useful for extending the
646 capabilities of the I<has> keyword: they are the simplest way to extend the MOP,
647 but they are still a fairly advanced topic and too much to cover here, see
648 L<Moose::Cookbook::Meta::Recipe1> for more information.
650 See L<Metaclass and Trait Name Resolution> for details on how a metaclass name
651 is resolved to a class name.
653 =item I<traits =E<gt> [ @role_names ]>
655 This tells Moose to take the list of C<@role_names> and apply them to the
656 attribute meta-object. This is very similar to the I<metaclass> option, but
657 allows you to use more than one extension at a time.
659 See L<Metaclass and Trait Name Resolution> for details on how a trait name is
660 resolved to a role name.
662 Also see L<Moose::Cookbook::Meta::Recipe3> for a metaclass trait
665 =item I<builder> => Str
667 The value of this key is the name of the method that will be called to
668 obtain the value used to initialize the attribute. See the L<builder
669 option docs in Class::MOP::Attribute|Class::MOP::Attribute/builder>
670 and/or L<Moose::Cookbook::Basics::Recipe8> for more information.
672 =item I<default> => SCALAR | CODE
674 The value of this key is the default value which will initialize the attribute.
676 NOTE: If the value is a simple scalar (string or number), then it can
677 be just passed as is. However, if you wish to initialize it with a
678 HASH or ARRAY ref, then you need to wrap that inside a CODE reference.
679 See the L<default option docs in
680 Class::MOP::Attribute|Class::MOP::Attribute/default> for more
683 =item I<clearer> => Str
685 Creates a method allowing you to clear the value, see the L<clearer option
686 docs in Class::MOP::Attribute|Class::MOP::Attribute/clearer> for more
689 =item I<predicate> => Str
691 Creates a method to perform a basic test to see if a value has been set in the
692 attribute, see the L<predicate option docs in
693 Class::MOP::Attribute|Class::MOP::Attribute/predicate> for more information.
695 =item I<lazy_build> => (0|1)
697 Automatically define lazy => 1 as well as builder => "_build_$attr", clearer =>
698 "clear_$attr', predicate => 'has_$attr' unless they are already defined.
700 =item I<initializer> => Str
702 This may be a method name (referring to a method on the class with
703 this attribute) or a CODE ref. The initializer is used to set the
704 attribute value on an instance when the attribute is set during
705 instance initialization (but not when the value is being assigned
706 to). See the L<initializer option docs in
707 Class::MOP::Attribute|Class::MOP::Attribute/initializer> for more
710 =item I<documentation> => $string
712 An arbitrary string that can be retrieved later by calling C<<
713 $attr->documentation >>.
719 =item B<has +$name =E<gt> %options>
721 This is variation on the normal attribute creator C<has> which allows you to
722 clone and extend an attribute from a superclass or from a role. Here is an
723 example of the superclass usage:
731 default => 'Hello, I am a Foo'
739 has '+message' => (default => 'Hello I am My::Foo');
741 What is happening here is that B<My::Foo> is cloning the C<message> attribute
742 from its parent class B<Foo>, retaining the C<is =E<gt> 'rw'> and C<isa =E<gt>
743 'Str'> characteristics, but changing the value in C<default>.
745 Here is another example, but within the context of a role:
753 default => 'Hello, I am a Foo'
761 has '+message' => (default => 'Hello I am My::Foo');
763 In this case, we are basically taking the attribute which the role supplied
764 and altering it within the bounds of this feature.
766 Note that you can only extend an attribute from either a superclass or a role,
767 you cannot extend an attribute in a role that composes over an attribute from
770 Aside from where the attributes come from (one from superclass, the other
771 from a role), this feature works exactly the same. This feature is restricted
772 somewhat, so as to try and force at least I<some> sanity into it. You are only
773 allowed to change the following attributes:
779 Change the default value of an attribute.
783 Change whether the attribute attempts to coerce a value passed to it.
787 Change if the attribute is required to have a value.
789 =item I<documentation>
791 Change the documentation string associated with the attribute.
795 Change if the attribute lazily initializes the slot.
799 You I<are> allowed to change the type without restriction.
801 It is recommended that you use this freedom with caution. We used to
802 only allow for extension only if the type was a subtype of the parent's
803 type, but we felt that was too restrictive and is better left as a
808 You are allowed to B<add> a new C<handles> definition, but you are B<not>
809 allowed to I<change> one.
813 You are allowed to B<add> a new C<builder> definition, but you are B<not>
814 allowed to I<change> one.
818 You are allowed to B<add> a new C<metaclass> definition, but you are
819 B<not> allowed to I<change> one.
823 You are allowed to B<add> additional traits to the C<traits> definition.
824 These traits will be composed into the attribute, but preexisting traits
825 B<are not> overridden, or removed.
829 =item B<before $name|@names|\@names|qr/.../ =E<gt> sub { ... }>
831 =item B<after $name|@names|\@names|qr/.../ =E<gt> sub { ... }>
833 =item B<around $name|@names|\@names|qr/.../ =E<gt> sub { ... }>
835 These three items are syntactic sugar for the before, after, and around method
836 modifier features that L<Class::MOP> provides. More information on these may be
837 found in L<Moose::Manual::MethodModifiers> and the
838 L<Class::MOP::Class documentation|Class::MOP::Class/"Method Modifiers">.
842 The keyword C<super> is a no-op when called outside of an C<override> method. In
843 the context of an C<override> method, it will call the next most appropriate
844 superclass method with the same arguments as the original method.
846 =item B<override ($name, &sub)>
848 An C<override> method is a way of explicitly saying "I am overriding this
849 method from my superclass". You can call C<super> within this method, and
850 it will work as expected. The same thing I<can> be accomplished with a normal
851 method call and the C<SUPER::> pseudo-package; it is really your choice.
855 The keyword C<inner>, much like C<super>, is a no-op outside of the context of
856 an C<augment> method. You can think of C<inner> as being the inverse of
857 C<super>; the details of how C<inner> and C<augment> work is best described in
858 the L<Moose::Cookbook::Basics::Recipe6>.
860 =item B<augment ($name, &sub)>
862 An C<augment> method, is a way of explicitly saying "I am augmenting this
863 method from my superclass". Once again, the details of how C<inner> and
864 C<augment> work is best described in the L<Moose::Cookbook::Basics::Recipe6>.
868 This is the C<Carp::confess> function, and exported here because I use it
873 This is the C<Scalar::Util::blessed> function, it is exported here because I
874 use it all the time. It is highly recommended that this is used instead of
875 C<ref> anywhere you need to test for an object's class name.
881 When you use Moose, you can specify which metaclass to use:
883 use Moose -metaclass => 'My::Meta::Class';
885 You can also specify traits which will be applied to your metaclass:
887 use Moose -traits => 'My::Trait';
889 This is very similar to the attribute traits feature. When you do
890 this, your class's C<meta> object will have the specified traits
891 applied to it. See L<Metaclass and Trait Name Resolution> for more
894 =head2 Metaclass and Trait Name Resolution
896 By default, when given a trait name, Moose simply tries to load a
897 class of the same name. If such a class does not exist, it then looks
898 for for a class matching
899 B<Moose::Meta::$type::Custom::Trait::$trait_name>. The C<$type>
900 variable here will be one of B<Attribute> or B<Class>, depending on
901 what the trait is being applied to.
903 If a class with this long name exists, Moose checks to see if it has
904 the method C<register_implementation>. This method is expected to
905 return the I<real> class name of the trait. If there is no
906 C<register_implementation> method, it will fall back to using
907 B<Moose::Meta::$type::Custom::Trait::$trait> as the trait name.
909 The lookup method for metaclasses is the same, except that it looks
910 for a class matching B<Moose::Meta::$type::Custom::$metaclass_name>.
912 If all this is confusing, take a look at
913 L<Moose::Cookbook::Meta::Recipe3>, which demonstrates how to create an
916 =head1 UNIMPORTING FUNCTIONS
920 Moose offers a way to remove the keywords it exports, through the C<unimport>
921 method. You simply have to say C<no Moose> at the bottom of your code for this
922 to work. Here is an example:
927 has 'first_name' => (is => 'rw', isa => 'Str');
928 has 'last_name' => (is => 'rw', isa => 'Str');
932 $self->first_name . ' ' . $self->last_name
935 no Moose; # keywords are removed from the Person package
937 =head1 EXTENDING AND EMBEDDING MOOSE
939 To learn more about extending Moose, we recommend checking out the
940 "Extending" recipes in the L<Moose::Cookbook>, starting with
941 L<Moose::Cookbook::Extending::Recipe1>, which provides an overview of
942 all the different ways you might extend Moose.
944 =head2 B<< Moose->init_meta(for_class => $class, base_class => $baseclass, metaclass => $metaclass) >>
946 The C<init_meta> method sets up the metaclass object for the class
947 specified by C<for_class>. This method injects a a C<meta> accessor
948 into the class so you can get at this object. It also sets the class's
949 superclass to C<base_class>, with L<Moose::Object> as the default.
951 C<init_meta> returns the metaclass object for C<$class>.
953 You can specify an alternate metaclass with the C<metaclass> option.
955 For more detail on this topic, see L<Moose::Cookbook::Extending::Recipe2>.
957 This method used to be documented as a function which accepted
958 positional parameters. This calling style will still work for
959 backwards compatibility, but is deprecated.
963 Moose's C<import> method supports the L<Sub::Exporter> form of C<{into =E<gt> $pkg}>
964 and C<{into_level =E<gt> 1}>.
966 B<NOTE>: Doing this is more or less deprecated. Use L<Moose::Exporter>
967 instead, which lets you stack multiple C<Moose.pm>-alike modules
968 sanely. It handles getting the exported functions into the right place
971 =head2 B<throw_error>
973 An alias for C<confess>, used by internally by Moose.
975 =head1 METACLASS COMPATIBILITY AND MOOSE
977 Metaclass compatibility is a thorny subject. You should start by
978 reading the "About Metaclass compatibility" section in the
981 Moose will attempt to resolve a few cases of metaclass incompatibility
982 when you set the superclasses for a class, in addition to the cases that
983 C<Class::MOP> handles.
985 Moose tries to determine if the metaclasses only "differ by roles". This
986 means that the parent and child's metaclass share a common ancestor in
987 their respective hierarchies, and that the subclasses under the common
988 ancestor are only different because of role applications. This case is
989 actually fairly common when you mix and match various C<MooseX::*>
990 modules, many of which apply roles to the metaclass.
992 If the parent and child do differ by roles, Moose replaces the
993 metaclass in the child with a newly created metaclass. This metaclass
994 is a subclass of the parent's metaclass, does all of the roles that
995 the child's metaclass did before being replaced. Effectively, this
996 means the new metaclass does all of the roles done by both the
997 parent's and child's original metaclasses.
999 Ultimately, this is all transparent to you except in the case of an
1000 unresolvable conflict.
1002 =head2 The MooseX:: namespace
1004 Generally if you're writing an extension I<for> Moose itself you'll want
1005 to put your extension in the C<MooseX::> namespace. This namespace is
1006 specifically for extensions that make Moose better or different in some
1007 fundamental way. It is traditionally B<not> for a package that just happens
1008 to use Moose. This namespace follows from the examples of the C<LWPx::>
1009 and C<DBIx::> namespaces that perform the same function for C<LWP> and C<DBI>
1018 It should be noted that C<super> and C<inner> B<cannot> be used in the same
1019 method. However, they may be combined within the same class hierarchy; see
1020 F<t/014_override_augment_inner_super.t> for an example.
1022 The reason for this is that C<super> is only valid within a method
1023 with the C<override> modifier, and C<inner> will never be valid within an
1024 C<override> method. In fact, C<augment> will skip over any C<override> methods
1025 when searching for its appropriate C<inner>.
1027 This might seem like a restriction, but I am of the opinion that keeping these
1028 two features separate (yet interoperable) actually makes them easy to use, since
1029 their behavior is then easier to predict. Time will tell whether I am right or
1030 not (UPDATE: so far so good).
1036 We offer both a mailing list and a very active IRC channel.
1038 The mailing list is L<moose@perl.org>. You must be subscribed to send
1039 a message. To subscribe, send an empty message to
1040 L<moose-subscribe@perl.org>
1042 You can also visit us at C<#moose> on L<irc://irc.perl.org/#moose>
1043 This channel is quite active, and questions at all levels (on Moose-related
1044 topics ;) are welcome.
1046 =head1 ACKNOWLEDGEMENTS
1050 =item I blame Sam Vilain for introducing me to the insanity that is meta-models.
1052 =item I blame Audrey Tang for then encouraging my meta-model habit in #perl6.
1054 =item Without Yuval "nothingmuch" Kogman this module would not be possible,
1055 and it certainly wouldn't have this name ;P
1057 =item The basis of the TypeContraints module was Rob Kinyon's idea
1058 originally, I just ran with it.
1060 =item Thanks to mst & chansen and the whole #moose posse for all the
1061 early ideas/feature-requests/encouragement/bug-finding.
1063 =item Thanks to David "Theory" Wheeler for meta-discussions and spelling fixes.
1071 =item L<http://www.iinteractive.com/moose>
1073 This is the official web home of Moose, it contains links to our public git repository
1074 as well as links to a number of talks and articles on Moose and Moose related
1077 =item The Moose is flying, a tutorial by Randal Schwartz
1079 Part 1 - L<http://www.stonehenge.com/merlyn/LinuxMag/col94.html>
1081 Part 2 - L<http://www.stonehenge.com/merlyn/LinuxMag/col95.html>
1083 =item Several Moose extension modules in the C<MooseX::> namespace.
1085 See L<http://search.cpan.org/search?query=MooseX::> for extensions.
1087 =item Moose stats on ohloh.net - L<http://www.ohloh.net/projects/moose>
1095 =item The Art of the MetaObject Protocol
1097 I mention this in the L<Class::MOP> docs too, this book was critical in
1098 the development of both modules and is highly recommended.
1106 =item L<http://www.cs.utah.edu/plt/publications/oopsla04-gff.pdf>
1108 This paper (suggested by lbr on #moose) was what lead to the implementation
1109 of the C<super>/C<override> and C<inner>/C<augment> features. If you really
1110 want to understand them, I suggest you read this.
1116 All complex software has bugs lurking in it, and this module is no
1119 Please report any bugs to C<bug-moose@rt.cpan.org>, or through the web
1120 interface at L<http://rt.cpan.org>.
1122 You can also discuss feature requests or possible bugs on the Moose mailing
1123 list (moose@perl.org) or on IRC at L<irc://irc.perl.org/#moose>.
1125 =head1 FEATURE REQUESTS
1127 We are very strict about what features we add to the Moose core, especially
1128 the user-visible features. Instead we have made sure that the underlying
1129 meta-system of Moose is as extensible as possible so that you can add your
1130 own features easily.
1132 That said, occasionally there is a feature needed in the meta-system
1133 to support your planned extension, in which case you should either
1134 email the mailing list (moose@perl.org) or join us on IRC at
1135 L<irc://irc.perl.org/#moose> to discuss. The
1136 L<Moose::Manual::Contributing> has more detail about how and when you
1141 Moose is an open project, there are at this point dozens of people who have
1142 contributed, and can contribute. If you have added anything to the Moose
1143 project you have a commit bit on this file and can add your name to the list.
1147 However there are only a few people with the rights to release a new version
1148 of Moose. The Moose Cabal are the people to go to with questions regarding
1149 the wider purview of Moose, and help out maintaining not just the code
1150 but the community as well.
1152 Stevan (stevan) Little E<lt>stevan@iinteractive.comE<gt>
1154 Jesse (doy) Luehrs E<lt>doy at tozt dot netE<gt>
1156 Yuval (nothingmuch) Kogman
1158 Shawn (sartak) Moore E<lt>sartak@bestpractical.comE<gt>
1160 Hans Dieter (confound) Pearcey E<lt>hdp@pobox.comE<gt>
1162 Chris (perigrin) Prather
1164 Florian Ragwitz E<lt>rafl@debian.orgE<gt>
1166 Dave (autarch) Rolsky E<lt>autarch@urth.orgE<gt>
1168 =head2 OTHER CONTRIBUTORS
1172 Adam (Alias) Kennedy
1174 Anders (Debolaz) Nor Berle
1176 Nathan (kolibrie) Gray
1178 Christian (chansen) Hansen
1180 Eric (ewilhelm) Wilhelm
1182 Guillermo (groditi) Roditi
1184 Jess (castaway) Robinson
1188 Robert (phaylon) Sedlacek
1192 Scott (konobi) McWhirter
1194 Shlomi (rindolf) Fish
1196 Wallace (wreis) Reis
1198 Jonathan (jrockway) Rockway
1200 Piotr (dexter) Roszatycki
1202 Sam (mugwump) Vilain
1206 Dylan Hardison (doc fixes)
1208 ... and many other #moose folks
1210 =head1 COPYRIGHT AND LICENSE
1212 Copyright 2006-2010 by Infinity Interactive, Inc.
1214 L<http://www.iinteractive.com>
1216 This library is free software; you can redistribute it and/or modify
1217 it under the same terms as Perl itself.