7 use Scalar::Util 'blessed';
10 use Moose::Deprecated;
15 use Moose::Meta::Class;
16 use Moose::Meta::TypeConstraint;
17 use Moose::Meta::TypeCoercion;
18 use Moose::Meta::Attribute;
19 use Moose::Meta::Instance;
23 use Moose::Meta::Role;
24 use Moose::Meta::Role::Composite;
25 use Moose::Meta::Role::Application;
26 use Moose::Meta::Role::Application::RoleSummation;
27 use Moose::Meta::Role::Application::ToClass;
28 use Moose::Meta::Role::Application::ToRole;
29 use Moose::Meta::Role::Application::ToInstance;
31 use Moose::Util::TypeConstraints;
34 use Moose::Meta::Attribute::Native;
45 Moose->throw_error("Must derive at least one class") unless @_;
47 # this checks the metaclass to make sure
48 # it is correct, sometimes it can get out
49 # of sync when the classes are being built
50 $meta->superclasses(@_);
54 Moose::Util::apply_all_roles(shift, @_);
61 Moose->throw_error('Usage: has \'name\' => ( key => value, ... )')
64 my %options = ( definition_context => Moose::Util::_caller_info(), @_ );
65 my $attrs = ( ref($name) eq 'ARRAY' ) ? $name : [ ($name) ];
66 $meta->add_attribute( $_, %options ) for @$attrs;
70 Moose::Util::add_method_modifier(shift, 'before', \@_);
74 Moose::Util::add_method_modifier(shift, 'after', \@_);
78 Moose::Util::add_method_modifier(shift, 'around', \@_);
86 # This check avoids a recursion loop - see
87 # t/100_bugs/020_super_recursion.t
88 return if defined $SUPER_PACKAGE && $SUPER_PACKAGE ne caller();
89 return unless $SUPER_BODY; $SUPER_BODY->(@SUPER_ARGS);
94 my ( $name, $method ) = @_;
95 $meta->add_override_method_modifier( $name => $method );
100 our ( %INNER_BODY, %INNER_ARGS );
102 if ( my $body = $INNER_BODY{$pkg} ) {
103 my @args = @{ $INNER_ARGS{$pkg} };
104 local $INNER_ARGS{$pkg};
105 local $INNER_BODY{$pkg};
106 return $body->(@args);
114 my ( $name, $method ) = @_;
115 $meta->add_augment_method_modifier( $name => $method );
118 Moose::Exporter->setup_import_methods(
120 qw( extends with has before after around override augment )
125 \&Scalar::Util::blessed,
130 # This used to be called as a function. This hack preserves
131 # backwards compatibility.
132 if ( $_[0] ne __PACKAGE__ ) {
133 Moose::Deprecated::deprecated(
134 feature => 'Moose::init_meta',
135 message => 'Calling Moose::init_meta as a function is deprecated',
138 return __PACKAGE__->init_meta(
148 my $class = $args{for_class}
149 or Moose->throw_error("Cannot call init_meta without specifying a for_class");
150 my $base_class = $args{base_class} || 'Moose::Object';
151 my $metaclass = $args{metaclass} || 'Moose::Meta::Class';
152 my $meta_name = exists $args{meta_name} ? $args{meta_name} : 'meta';
154 Moose->throw_error("The Metaclass $metaclass must be a subclass of Moose::Meta::Class.")
155 unless $metaclass->isa('Moose::Meta::Class');
157 # make a subtype for each Moose class
159 unless find_type_constraint($class);
163 if ( $meta = Class::MOP::get_metaclass_by_name($class) ) {
164 unless ( $meta->isa("Moose::Meta::Class") ) {
165 my $error_message = "$class already has a metaclass, but it does not inherit $metaclass ($meta).";
166 if ( $meta->isa('Moose::Meta::Role') ) {
167 Moose->throw_error($error_message . ' You cannot make the same thing a role and a class. Remove either Moose or Moose::Role.');
169 Moose->throw_error($error_message);
175 # now we check whether our ancestors have metaclass, and if so borrow that
176 my ( undef, @isa ) = @{ mro::get_linear_isa($class) };
178 foreach my $ancestor ( @isa ) {
179 my $ancestor_meta = Class::MOP::get_metaclass_by_name($ancestor) || next;
181 my $ancestor_meta_class = $ancestor_meta->_real_ref_name;
183 # if we have an ancestor metaclass that inherits $metaclass, we use
184 # that. This is like _fix_metaclass_incompatibility, but we can do it now.
186 # the case of having an ancestry is not very common, but arises in
188 unless ( $metaclass->isa( $ancestor_meta_class ) ) {
189 if ( $ancestor_meta_class->isa($metaclass) ) {
190 $metaclass = $ancestor_meta_class;
195 $meta = $metaclass->initialize($class);
198 if (defined $meta_name) {
199 # also check for inherited non moose 'meta' method?
200 my $existing = $meta->get_method($meta_name);
201 if ($existing && !$existing->isa('Class::MOP::Method::Meta')) {
202 Carp::cluck "Moose is overwriting an existing method named "
203 . "$meta_name in class $class with a method "
204 . "which returns the class's metaclass. If this is "
205 . "actually what you want, you should remove the "
206 . "existing method, otherwise, you should rename or "
207 . "disable this generated method using the "
208 . "'-meta_name' option to 'use Moose'.";
210 $meta->_add_meta_method($meta_name);
213 # make sure they inherit from Moose::Object
214 $meta->superclasses($base_class)
215 unless $meta->superclasses();
220 # This may be used in some older MooseX extensions.
222 goto &Moose::Exporter::_get_caller;
225 ## make 'em all immutable
228 inline_constructor => 1,
229 constructor_name => "_new",
230 # these are Class::MOP accessors, so they need inlining
231 inline_accessors => 1
232 ) for grep { $_->is_mutable }
235 Moose::Meta::Attribute
237 Moose::Meta::Instance
239 Moose::Meta::TypeCoercion
240 Moose::Meta::TypeCoercion::Union
243 Moose::Meta::Method::Accessor
244 Moose::Meta::Method::Constructor
245 Moose::Meta::Method::Destructor
246 Moose::Meta::Method::Overridden
247 Moose::Meta::Method::Augmented
250 Moose::Meta::Role::Attribute
251 Moose::Meta::Role::Method
252 Moose::Meta::Role::Method::Required
253 Moose::Meta::Role::Method::Conflicting
255 Moose::Meta::Role::Composite
257 Moose::Meta::Role::Application
258 Moose::Meta::Role::Application::RoleSummation
259 Moose::Meta::Role::Application::ToClass
260 Moose::Meta::Role::Application::ToRole
261 Moose::Meta::Role::Application::ToInstance
264 Moose::Meta::Mixin::AttributeCore->meta->make_immutable(
265 inline_constructor => 0,
266 constructor_name => undef,
271 # ABSTRACT: A postmodern object system for Perl 5
280 use Moose; # automatically turns on strict and warnings
282 has 'x' => (is => 'rw', isa => 'Int');
283 has 'y' => (is => 'rw', isa => 'Int');
296 has 'z' => (is => 'rw', isa => 'Int');
298 after 'clear' => sub {
305 Moose is an extension of the Perl 5 object system.
307 The main goal of Moose is to make Perl 5 Object Oriented programming
308 easier, more consistent, and less tedious. With Moose you can think
309 more about what you want to do and less about the mechanics of OOP.
311 Additionally, Moose is built on top of L<Class::MOP>, which is a
312 metaclass system for Perl 5. This means that Moose not only makes
313 building normal Perl 5 objects better, but it provides the power of
314 metaclass programming as well.
318 If you're new to Moose, the best place to start is the
319 L<Moose::Manual> docs, followed by the L<Moose::Cookbook>. The intro
320 will show you what Moose is, and how it makes Perl 5 OO better.
322 The cookbook recipes on Moose basics will get you up to speed with
323 many of Moose's features quickly. Once you have an idea of what Moose
324 can do, you can use the API documentation to get more detail on
325 features which interest you.
327 =head2 Moose Extensions
329 The C<MooseX::> namespace is the official place to find Moose extensions.
330 These extensions can be found on the CPAN. The easiest way to find them
331 is to search for them (L<http://search.cpan.org/search?query=MooseX::>),
332 or to examine L<Task::Moose> which aims to keep an up-to-date, easily
333 installable list of Moose extensions.
337 Much of the Moose documentation has been translated into other languages.
343 Japanese docs can be found at
344 L<http://perldoc.perlassociation.org/pod/Moose-Doc-JA/index.html>. The
345 source POD files can be found in GitHub:
346 L<http://github.com/jpa/Moose-Doc-JA>
350 =head1 BUILDING CLASSES WITH MOOSE
352 Moose makes every attempt to provide as much convenience as possible during
353 class construction/definition, but still stay out of your way if you want it
354 to. Here are a few items to note when building classes with Moose.
356 When you C<use Moose>, Moose will set the class's parent class to
357 L<Moose::Object>, I<unless> the class using Moose already has a parent
358 class. In addition, specifying a parent with C<extends> will change the parent
361 Moose will also manage all attributes (including inherited ones) that are
362 defined with C<has>. And (assuming you call C<new>, which is inherited from
363 L<Moose::Object>) this includes properly initializing all instance slots,
364 setting defaults where appropriate, and performing any type constraint checking
367 =head1 PROVIDED METHODS
369 Moose provides a number of methods to all your classes, mostly through the
370 inheritance of L<Moose::Object>. There is however, one exception.
376 This is a method which provides access to the current class's metaclass.
380 =head1 EXPORTED FUNCTIONS
382 Moose will export a number of functions into the class's namespace which
383 may then be used to set up the class. These functions all work directly
384 on the current class.
388 =item B<extends (@superclasses)>
390 This function will set the superclass(es) for the current class.
392 This approach is recommended instead of C<use base>, because C<use base>
393 actually C<push>es onto the class's C<@ISA>, whereas C<extends> will
394 replace it. This is important to ensure that classes which do not have
395 superclasses still properly inherit from L<Moose::Object>.
397 Each superclass can be followed by a hash reference with options. Currently,
398 only L<-version|Class::MOP/Class Loading Options> is recognized:
400 extends 'My::Parent' => { -version => 0.01 },
401 'My::OtherParent' => { -version => 0.03 };
403 An exception will be thrown if the version requirements are not
406 =item B<with (@roles)>
408 This will apply a given set of C<@roles> to the local class.
410 Like with C<extends>, each specified role can be followed by a hash
411 reference with a L<-version|Class::MOP/Class Loading Options> option:
413 with 'My::Role' => { -version => 0.32 },
414 'My::Otherrole' => { -version => 0.23 };
416 The specified version requirements must be satisfied, otherwise an
417 exception will be thrown.
419 If your role takes options or arguments, they can be passed along in the
420 hash reference as well.
422 =item B<has $name|@$names =E<gt> %options>
424 This will install an attribute of a given C<$name> into the current class. If
425 the first parameter is an array reference, it will create an attribute for
426 every C<$name> in the list. The C<%options> are the same as those provided by
427 L<Class::MOP::Attribute>, in addition to the list below which are provided by
428 Moose (L<Moose::Meta::Attribute> to be more specific):
432 =item I<is =E<gt> 'rw'|'ro'>
434 The I<is> option accepts either I<rw> (for read/write) or I<ro> (for read
435 only). These will create either a read/write accessor or a read-only
436 accessor respectively, using the same name as the C<$name> of the attribute.
438 If you need more control over how your accessors are named, you can
439 use the L<reader|Class::MOP::Attribute/reader>,
440 L<writer|Class::MOP::Attribute/writer> and
441 L<accessor|Class::MOP::Attribute/accessor> options inherited from
442 L<Class::MOP::Attribute>, however if you use those, you won't need the
445 =item I<isa =E<gt> $type_name>
447 The I<isa> option uses Moose's type constraint facilities to set up runtime
448 type checking for this attribute. Moose will perform the checks during class
449 construction, and within any accessors. The C<$type_name> argument must be a
450 string. The string may be either a class name or a type defined using
451 Moose's type definition features. (Refer to L<Moose::Util::TypeConstraints>
452 for information on how to define a new type, and how to retrieve type meta-data).
454 =item I<coerce =E<gt> (1|0)>
456 This will attempt to use coercion with the supplied type constraint to change
457 the value passed into any accessors or constructors. You B<must> supply a type
458 constraint, and that type constraint B<must> define a coercion. See
459 L<Moose::Cookbook::Basics::Recipe5> for an example.
461 =item I<does =E<gt> $role_name>
463 This will accept the name of a role which the value stored in this attribute
464 is expected to have consumed.
466 =item I<required =E<gt> (1|0)>
468 This marks the attribute as being required. This means a value must be
469 supplied during class construction, I<or> the attribute must be lazy
470 and have either a default or a builder. Note that c<required> does not
471 say anything about the attribute's value, which can be C<undef>.
473 =item I<weak_ref =E<gt> (1|0)>
475 This will tell the class to store the value of this attribute as a weakened
476 reference. If an attribute is a weakened reference, it B<cannot> also be
479 =item I<lazy =E<gt> (1|0)>
481 This will tell the class to not create this slot until absolutely necessary.
482 If an attribute is marked as lazy it B<must> have a default supplied.
484 =item I<auto_deref =E<gt> (1|0)>
486 This tells the accessor to automatically dereference the value of this
487 attribute when called in list context. The accessor will still return a
488 reference when called in scalar context. If this behavior isn't desirable,
489 L<Moose::Meta::Attribute::Native::Trait::Array/elements> or
490 L<Moose::Meta::Attribute::Native::Trait::Hash/elements> may be a better
491 choice. The I<auto_deref> option is only legal if your I<isa> option is
492 either C<ArrayRef> or C<HashRef>.
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<metaclass =E<gt> $metaclass_name>
635 This tells the class to use a custom attribute metaclass for this particular
636 attribute. Custom attribute metaclasses are useful for extending the
637 capabilities of the I<has> keyword: they are the simplest way to extend the MOP,
638 but they are still a fairly advanced topic and too much to cover here. See
639 L<Moose::Cookbook::Meta::Recipe1> for more information.
641 See L<Metaclass and Trait Name Resolution> for details on how a metaclass name
642 is resolved to a class name.
644 =item I<traits =E<gt> [ @role_names ]>
646 This tells Moose to take the list of C<@role_names> and apply them to the
647 attribute meta-object. This is very similar to the I<metaclass> option, but
648 allows you to use more than one extension at a time.
650 See L<Metaclass and Trait Name Resolution> for details on how a trait name is
651 resolved to a role name.
653 Also see L<Moose::Cookbook::Meta::Recipe3> for a metaclass trait
656 =item I<builder> => Str
658 The value of this key is the name of the method that will be called to
659 obtain the value used to initialize the attribute. See the L<builder
660 option docs in Class::MOP::Attribute|Class::MOP::Attribute/builder>
661 and/or L<Moose::Cookbook::Basics::Recipe8> for more information.
663 =item I<default> => SCALAR | CODE
665 The value of this key is the default value which will initialize the attribute.
667 NOTE: If the value is a simple scalar (string or number), then it can
668 be just passed as is. However, if you wish to initialize it with a
669 HASH or ARRAY ref, then you need to wrap that inside a CODE reference.
670 See the L<default option docs in
671 Class::MOP::Attribute|Class::MOP::Attribute/default> for more
674 =item I<clearer> => Str
676 Creates a method allowing you to clear the value. See the L<clearer option
677 docs in Class::MOP::Attribute|Class::MOP::Attribute/clearer> for more
680 =item I<predicate> => Str
682 Creates a method to perform a basic test to see if a value has been set in the
683 attribute. See the L<predicate option docs in
684 Class::MOP::Attribute|Class::MOP::Attribute/predicate> for more information.
686 =item I<lazy_build> => (0|1)
688 Automatically define lazy => 1 as well as builder => "_build_$attr", clearer =>
689 "clear_$attr', predicate => 'has_$attr' unless they are already defined.
691 =item I<initializer> => Str
693 This may be a method name (referring to a method on the class with
694 this attribute) or a CODE ref. The initializer is used to set the
695 attribute value on an instance when the attribute is set during
696 instance initialization (but not when the value is being assigned
697 to). See the L<initializer option docs in
698 Class::MOP::Attribute|Class::MOP::Attribute/initializer> for more
701 =item I<documentation> => $string
703 An arbitrary string that can be retrieved later by calling C<<
704 $attr->documentation >>.
710 =item B<has +$name =E<gt> %options>
712 This is variation on the normal attribute creator C<has> which allows you to
713 clone and extend an attribute from a superclass or from a role. Here is an
714 example of the superclass usage:
722 default => 'Hello, I am a Foo'
730 has '+message' => (default => 'Hello I am My::Foo');
732 What is happening here is that B<My::Foo> is cloning the C<message> attribute
733 from its parent class B<Foo>, retaining the C<is =E<gt> 'rw'> and C<isa =E<gt>
734 'Str'> characteristics, but changing the value in C<default>.
736 Here is another example, but within the context of a role:
744 default => 'Hello, I am a Foo'
752 has '+message' => (default => 'Hello I am My::Foo');
754 In this case, we are basically taking the attribute which the role supplied
755 and altering it within the bounds of this feature.
757 Note that you can only extend an attribute from either a superclass or a role,
758 you cannot extend an attribute in a role that composes over an attribute from
761 Aside from where the attributes come from (one from superclass, the other
762 from a role), this feature works exactly the same. This feature is restricted
763 somewhat, so as to try and force at least I<some> sanity into it. You are only
764 allowed to change the following attributes:
770 Change the default value of an attribute.
774 Change whether the attribute attempts to coerce a value passed to it.
778 Change if the attribute is required to have a value.
780 =item I<documentation>
782 Change the documentation string associated with the attribute.
786 Change if the attribute lazily initializes the slot.
790 You I<are> allowed to change the type without restriction.
792 It is recommended that you use this freedom with caution. We used to
793 only allow for extension only if the type was a subtype of the parent's
794 type, but we felt that was too restrictive and is better left as a
799 You are allowed to B<add> a new C<handles> definition, but you are B<not>
800 allowed to I<change> one.
804 You are allowed to B<add> a new C<builder> definition, but you are B<not>
805 allowed to I<change> one.
809 You are allowed to B<add> a new C<metaclass> definition, but you are
810 B<not> allowed to I<change> one.
814 You are allowed to B<add> additional traits to the C<traits> definition.
815 These traits will be composed into the attribute, but preexisting traits
816 B<are not> overridden, or removed.
820 =item B<before $name|@names|\@names|qr/.../ =E<gt> sub { ... }>
822 =item B<after $name|@names|\@names|qr/.../ =E<gt> sub { ... }>
824 =item B<around $name|@names|\@names|qr/.../ =E<gt> sub { ... }>
826 These three items are syntactic sugar for the before, after, and around method
827 modifier features that L<Class::MOP> provides. More information on these may be
828 found in L<Moose::Manual::MethodModifiers> and the
829 L<Class::MOP::Class documentation|Class::MOP::Class/"Method Modifiers">.
833 The keyword C<super> is a no-op when called outside of an C<override> method. In
834 the context of an C<override> method, it will call the next most appropriate
835 superclass method with the same arguments as the original method.
837 =item B<override ($name, &sub)>
839 An C<override> method is a way of explicitly saying "I am overriding this
840 method from my superclass". You can call C<super> within this method, and
841 it will work as expected. The same thing I<can> be accomplished with a normal
842 method call and the C<SUPER::> pseudo-package; it is really your choice.
846 The keyword C<inner>, much like C<super>, is a no-op outside of the context of
847 an C<augment> method. You can think of C<inner> as being the inverse of
848 C<super>; the details of how C<inner> and C<augment> work is best described in
849 the L<Moose::Cookbook::Basics::Recipe6>.
851 =item B<augment ($name, &sub)>
853 An C<augment> method, is a way of explicitly saying "I am augmenting this
854 method from my superclass". Once again, the details of how C<inner> and
855 C<augment> work is best described in the L<Moose::Cookbook::Basics::Recipe6>.
859 This is the C<Carp::confess> function, and exported here because I use it
864 This is the C<Scalar::Util::blessed> function. It is exported here because I
865 use it all the time. It is highly recommended that this is used instead of
866 C<ref> anywhere you need to test for an object's class name.
872 When you use Moose, you can specify which metaclass to use:
874 use Moose -metaclass => 'My::Meta::Class';
876 You can also specify traits which will be applied to your metaclass:
878 use Moose -traits => 'My::Trait';
880 This is very similar to the attribute traits feature. When you do
881 this, your class's C<meta> object will have the specified traits
882 applied to it. See L<Metaclass and Trait Name Resolution> for more
885 =head2 Metaclass and Trait Name Resolution
887 By default, when given a trait name, Moose simply tries to load a
888 class of the same name. If such a class does not exist, it then looks
889 for for a class matching
890 B<Moose::Meta::$type::Custom::Trait::$trait_name>. The C<$type>
891 variable here will be one of B<Attribute> or B<Class>, depending on
892 what the trait is being applied to.
894 If a class with this long name exists, Moose checks to see if it has
895 the method C<register_implementation>. This method is expected to
896 return the I<real> class name of the trait. If there is no
897 C<register_implementation> method, it will fall back to using
898 B<Moose::Meta::$type::Custom::Trait::$trait> as the trait name.
900 The lookup method for metaclasses is the same, except that it looks
901 for a class matching B<Moose::Meta::$type::Custom::$metaclass_name>.
903 If all this is confusing, take a look at
904 L<Moose::Cookbook::Meta::Recipe3>, which demonstrates how to create an
907 =head1 UNIMPORTING FUNCTIONS
911 Moose offers a way to remove the keywords it exports, through the C<unimport>
912 method. You simply have to say C<no Moose> at the bottom of your code for this
913 to work. Here is an example:
918 has 'first_name' => (is => 'rw', isa => 'Str');
919 has 'last_name' => (is => 'rw', isa => 'Str');
923 $self->first_name . ' ' . $self->last_name
926 no Moose; # keywords are removed from the Person package
928 =head1 EXTENDING AND EMBEDDING MOOSE
930 To learn more about extending Moose, we recommend checking out the
931 "Extending" recipes in the L<Moose::Cookbook>, starting with
932 L<Moose::Cookbook::Extending::Recipe1>, which provides an overview of
933 all the different ways you might extend Moose.
935 =head2 B<< Moose->init_meta(for_class => $class, base_class => $baseclass, metaclass => $metaclass) >>
937 The C<init_meta> method sets up the metaclass object for the class
938 specified by C<for_class>. This method injects a a C<meta> accessor
939 into the class so you can get at this object. It also sets the class's
940 superclass to C<base_class>, with L<Moose::Object> as the default.
942 C<init_meta> returns the metaclass object for C<$class>.
944 You can specify an alternate metaclass with the C<metaclass> option.
946 For more detail on this topic, see L<Moose::Cookbook::Extending::Recipe2>.
948 This method used to be documented as a function which accepted
949 positional parameters. This calling style will still work for
950 backwards compatibility, but is deprecated.
954 Moose's C<import> method supports the L<Sub::Exporter> form of C<{into =E<gt> $pkg}>
955 and C<{into_level =E<gt> 1}>.
957 B<NOTE>: Doing this is more or less deprecated. Use L<Moose::Exporter>
958 instead, which lets you stack multiple C<Moose.pm>-alike modules
959 sanely. It handles getting the exported functions into the right place
962 =head2 B<throw_error>
964 An alias for C<confess>, used internally by Moose.
966 =head2 The MooseX:: namespace
968 Generally if you're writing an extension I<for> Moose itself you'll want
969 to put your extension in the C<MooseX::> namespace. This namespace is
970 specifically for extensions that make Moose better or different in some
971 fundamental way. It is traditionally B<not> for a package that just happens
972 to use Moose. This namespace follows from the examples of the C<LWPx::>
973 and C<DBIx::> namespaces that perform the same function for C<LWP> and C<DBI>
976 =head1 METACLASS COMPATIBILITY AND MOOSE
978 Metaclass compatibility is a thorny subject. You should start by
979 reading the "About Metaclass compatibility" section in the
982 Moose will attempt to resolve a few cases of metaclass incompatibility
983 when you set the superclasses for a class, in addition to the cases that
984 C<Class::MOP> handles.
986 Moose tries to determine if the metaclasses only "differ by roles". This
987 means that the parent and child's metaclass share a common ancestor in
988 their respective hierarchies, and that the subclasses under the common
989 ancestor are only different because of role applications. This case is
990 actually fairly common when you mix and match various C<MooseX::*>
991 modules, many of which apply roles to the metaclass.
993 If the parent and child do differ by roles, Moose replaces the
994 metaclass in the child with a newly created metaclass. This metaclass
995 is a subclass of the parent's metaclass which does all of the roles that
996 the child's metaclass did before being replaced. Effectively, this
997 means the new metaclass does all of the roles done by both the
998 parent's and child's original metaclasses.
1000 Ultimately, this is all transparent to you except in the case of an
1001 unresolvable conflict.
1009 It should be noted that C<super> and C<inner> B<cannot> be used in the same
1010 method. However, they may be combined within the same class hierarchy; see
1011 F<t/014_override_augment_inner_super.t> for an example.
1013 The reason for this is that C<super> is only valid within a method
1014 with the C<override> modifier, and C<inner> will never be valid within an
1015 C<override> method. In fact, C<augment> will skip over any C<override> methods
1016 when searching for its appropriate C<inner>.
1018 This might seem like a restriction, but I am of the opinion that keeping these
1019 two features separate (yet interoperable) actually makes them easy to use, since
1020 their behavior is then easier to predict. Time will tell whether I am right or
1021 not (UPDATE: so far so good).
1027 We offer both a mailing list and a very active IRC channel.
1029 The mailing list is L<moose@perl.org>. You must be subscribed to send
1030 a message. To subscribe, send an empty message to
1031 L<moose-subscribe@perl.org>
1033 You can also visit us at C<#moose> on L<irc://irc.perl.org/#moose>
1034 This channel is quite active, and questions at all levels (on Moose-related
1035 topics ;) are welcome.
1037 =head1 ACKNOWLEDGEMENTS
1041 =item I blame Sam Vilain for introducing me to the insanity that is meta-models.
1043 =item I blame Audrey Tang for then encouraging my meta-model habit in #perl6.
1045 =item Without Yuval "nothingmuch" Kogman this module would not be possible,
1046 and it certainly wouldn't have this name ;P
1048 =item The basis of the TypeContraints module was Rob Kinyon's idea
1049 originally, I just ran with it.
1051 =item Thanks to mst & chansen and the whole #moose posse for all the
1052 early ideas/feature-requests/encouragement/bug-finding.
1054 =item Thanks to David "Theory" Wheeler for meta-discussions and spelling fixes.
1062 =item L<http://www.iinteractive.com/moose>
1064 This is the official web home of Moose, it contains links to our public git repository
1065 as well as links to a number of talks and articles on Moose and Moose related
1068 =item The Moose is flying, a tutorial by Randal Schwartz
1070 Part 1 - L<http://www.stonehenge.com/merlyn/LinuxMag/col94.html>
1072 Part 2 - L<http://www.stonehenge.com/merlyn/LinuxMag/col95.html>
1074 =item Several Moose extension modules in the C<MooseX::> namespace.
1076 See L<http://search.cpan.org/search?query=MooseX::> for extensions.
1078 =item Moose stats on ohloh.net - L<http://www.ohloh.net/projects/moose>
1086 =item The Art of the MetaObject Protocol
1088 I mention this in the L<Class::MOP> docs too, as this book was critical in
1089 the development of both modules and is highly recommended.
1097 =item L<http://www.cs.utah.edu/plt/publications/oopsla04-gff.pdf>
1099 This paper (suggested by lbr on #moose) was what lead to the implementation
1100 of the C<super>/C<override> and C<inner>/C<augment> features. If you really
1101 want to understand them, I suggest you read this.
1107 All complex software has bugs lurking in it, and this module is no
1110 Please report any bugs to C<bug-moose@rt.cpan.org>, or through the web
1111 interface at L<http://rt.cpan.org>.
1113 You can also discuss feature requests or possible bugs on the Moose mailing
1114 list (moose@perl.org) or on IRC at L<irc://irc.perl.org/#moose>.
1116 =head1 FEATURE REQUESTS
1118 We are very strict about what features we add to the Moose core, especially
1119 the user-visible features. Instead we have made sure that the underlying
1120 meta-system of Moose is as extensible as possible so that you can add your
1121 own features easily.
1123 That said, occasionally there is a feature needed in the meta-system
1124 to support your planned extension, in which case you should either
1125 email the mailing list (moose@perl.org) or join us on IRC at
1126 L<irc://irc.perl.org/#moose> to discuss. The
1127 L<Moose::Manual::Contributing> has more detail about how and when you
1132 There are only a few people with the rights to release a new version
1133 of Moose. The Moose Cabal are the people to go to with questions regarding
1134 the wider purview of Moose. They help maintain not just the code
1135 but the community as well.
1137 Stevan (stevan) Little E<lt>stevan@iinteractive.comE<gt>
1139 Jesse (doy) Luehrs E<lt>doy at tozt dot netE<gt>
1141 Yuval (nothingmuch) Kogman
1143 Shawn (sartak) Moore E<lt>sartak@bestpractical.comE<gt>
1145 Hans Dieter (confound) Pearcey E<lt>hdp@pobox.comE<gt>
1147 Chris (perigrin) Prather
1149 Florian Ragwitz E<lt>rafl@debian.orgE<gt>
1151 Dave (autarch) Rolsky E<lt>autarch@urth.orgE<gt>
1157 Adam (Alias) Kennedy
1159 Anders (Debolaz) Nor Berle
1161 Chris (perigrin) Prather
1163 Christian (chansen) Hansen
1167 Dylan Hardison (doc fixes)
1169 Eric (ewilhelm) Wilhelm
1173 Florian (rafl) Ragwitz
1175 Guillermo (groditi) Roditi
1181 Jess (castaway) Robinson
1183 Jonathan (jrockway) Rockway
1187 Nathan (kolibrie) Gray
1189 Paul (frodwith) Driver
1191 Piotr (dexter) Roszatycki
1195 Robert (phaylon) Sedlacek
1199 Sam (mugwump) Vilain
1201 Scott (konobi) McWhirter
1203 Shawn (Sartak) Moore
1205 Shlomi (rindolf) Fish
1209 Wallace (wreis) Reis
1211 ... and many other #moose folks