7 our $AUTHORITY = 'cpan:STEVAN';
9 use Scalar::Util 'blessed';
12 use Moose::Deprecated;
17 use Moose::Meta::Class;
18 use Moose::Meta::TypeConstraint;
19 use Moose::Meta::TypeCoercion;
20 use Moose::Meta::Attribute;
21 use Moose::Meta::Instance;
25 use Moose::Meta::Role;
26 use Moose::Meta::Role::Composite;
27 use Moose::Meta::Role::Application;
28 use Moose::Meta::Role::Application::RoleSummation;
29 use Moose::Meta::Role::Application::ToClass;
30 use Moose::Meta::Role::Application::ToRole;
31 use Moose::Meta::Role::Application::ToInstance;
33 use Moose::Util::TypeConstraints;
36 use Moose::Meta::Attribute::Native;
47 Moose->throw_error("Must derive at least one class") unless @_;
49 # this checks the metaclass to make sure
50 # it is correct, sometimes it can get out
51 # of sync when the classes are being built
52 $meta->superclasses(@_);
56 Moose::Util::apply_all_roles(shift, @_);
63 Moose->throw_error('Usage: has \'name\' => ( key => value, ... )')
66 my %options = ( definition_context => Moose::Util::_caller_info(), @_ );
67 my $attrs = ( ref($name) eq 'ARRAY' ) ? $name : [ ($name) ];
68 $meta->add_attribute( $_, %options ) for @$attrs;
72 Moose::Util::add_method_modifier(shift, 'before', \@_);
76 Moose::Util::add_method_modifier(shift, 'after', \@_);
80 Moose::Util::add_method_modifier(shift, 'around', \@_);
88 # This check avoids a recursion loop - see
89 # t/100_bugs/020_super_recursion.t
90 return if defined $SUPER_PACKAGE && $SUPER_PACKAGE ne caller();
91 return unless $SUPER_BODY; $SUPER_BODY->(@SUPER_ARGS);
96 my ( $name, $method ) = @_;
97 $meta->add_override_method_modifier( $name => $method );
102 our ( %INNER_BODY, %INNER_ARGS );
104 if ( my $body = $INNER_BODY{$pkg} ) {
105 my @args = @{ $INNER_ARGS{$pkg} };
106 local $INNER_ARGS{$pkg};
107 local $INNER_BODY{$pkg};
108 return $body->(@args);
116 my ( $name, $method ) = @_;
117 $meta->add_augment_method_modifier( $name => $method );
120 Moose::Exporter->setup_import_methods(
122 qw( extends with has before after around override augment )
127 \&Scalar::Util::blessed,
132 # This used to be called as a function. This hack preserves
133 # backwards compatibility.
134 if ( $_[0] ne __PACKAGE__ ) {
135 Moose::Deprecated::deprecated(
136 feature => 'Moose::init_meta',
137 message => 'Calling Moose::init_meta as a function is deprecated',
140 return __PACKAGE__->init_meta(
150 my $class = $args{for_class}
151 or Moose->throw_error("Cannot call init_meta without specifying a for_class");
152 my $base_class = $args{base_class} || 'Moose::Object';
153 my $metaclass = $args{metaclass} || 'Moose::Meta::Class';
154 my $meta_name = exists $args{meta_name} ? $args{meta_name} : 'meta';
156 Moose->throw_error("The Metaclass $metaclass must be a subclass of Moose::Meta::Class.")
157 unless $metaclass->isa('Moose::Meta::Class');
159 # make a subtype for each Moose class
161 unless find_type_constraint($class);
165 if ( $meta = Class::MOP::get_metaclass_by_name($class) ) {
166 unless ( $meta->isa("Moose::Meta::Class") ) {
167 my $error_message = "$class already has a metaclass, but it does not inherit $metaclass ($meta).";
168 if ( $meta->isa('Moose::Meta::Role') ) {
169 Moose->throw_error($error_message . ' You cannot make the same thing a role and a class. Remove either Moose or Moose::Role.');
171 Moose->throw_error($error_message);
177 # now we check whether our ancestors have metaclass, and if so borrow that
178 my ( undef, @isa ) = @{ mro::get_linear_isa($class) };
180 foreach my $ancestor ( @isa ) {
181 my $ancestor_meta = Class::MOP::get_metaclass_by_name($ancestor) || next;
183 my $ancestor_meta_class = $ancestor_meta->_real_ref_name;
185 # if we have an ancestor metaclass that inherits $metaclass, we use
186 # that. This is like _fix_metaclass_incompatibility, but we can do it now.
188 # the case of having an ancestry is not very common, but arises in
190 unless ( $metaclass->isa( $ancestor_meta_class ) ) {
191 if ( $ancestor_meta_class->isa($metaclass) ) {
192 $metaclass = $ancestor_meta_class;
197 $meta = $metaclass->initialize($class);
200 if (defined $meta_name) {
201 # also check for inherited non moose 'meta' method?
202 my $existing = $meta->get_method($meta_name);
203 if ($existing && !$existing->isa('Class::MOP::Method::Meta')) {
204 Carp::cluck "Moose is overwriting an existing method named "
205 . "$meta_name in class $class with a method "
206 . "which returns the class's metaclass. If this is "
207 . "actually what you want, you should remove the "
208 . "existing method, otherwise, you should rename or "
209 . "disable this generated method using the "
210 . "'-meta_name' option to 'use Moose'.";
212 $meta->_add_meta_method($meta_name);
215 # make sure they inherit from Moose::Object
216 $meta->superclasses($base_class)
217 unless $meta->superclasses();
222 # This may be used in some older MooseX extensions.
224 goto &Moose::Exporter::_get_caller;
227 ## make 'em all immutable
230 inline_constructor => 1,
231 constructor_name => "_new",
232 # these are Class::MOP accessors, so they need inlining
233 inline_accessors => 1
234 ) for grep { $_->is_mutable }
237 Moose::Meta::Attribute
239 Moose::Meta::Instance
241 Moose::Meta::TypeCoercion
242 Moose::Meta::TypeCoercion::Union
245 Moose::Meta::Method::Accessor
246 Moose::Meta::Method::Constructor
247 Moose::Meta::Method::Destructor
248 Moose::Meta::Method::Overridden
249 Moose::Meta::Method::Augmented
252 Moose::Meta::Role::Attribute
253 Moose::Meta::Role::Method
254 Moose::Meta::Role::Method::Required
255 Moose::Meta::Role::Method::Conflicting
257 Moose::Meta::Role::Composite
259 Moose::Meta::Role::Application
260 Moose::Meta::Role::Application::RoleSummation
261 Moose::Meta::Role::Application::ToClass
262 Moose::Meta::Role::Application::ToRole
263 Moose::Meta::Role::Application::ToInstance
266 Moose::Meta::Mixin::AttributeCore->meta->make_immutable(
267 inline_constructor => 0,
268 constructor_name => undef,
273 # ABSTRACT: A postmodern object system for Perl 5
282 use Moose; # automatically turns on strict and warnings
284 has 'x' => (is => 'rw', isa => 'Int');
285 has 'y' => (is => 'rw', isa => 'Int');
298 has 'z' => (is => 'rw', isa => 'Int');
300 after 'clear' => sub {
307 Moose is an extension of the Perl 5 object system.
309 The main goal of Moose is to make Perl 5 Object Oriented programming
310 easier, more consistent, and less tedious. With Moose you can think
311 more about what you want to do and less about the mechanics of OOP.
313 Additionally, Moose is built on top of L<Class::MOP>, which is a
314 metaclass system for Perl 5. This means that Moose not only makes
315 building normal Perl 5 objects better, but it provides the power of
316 metaclass programming as well.
320 If you're new to Moose, the best place to start is the
321 L<Moose::Manual> docs, followed by the L<Moose::Cookbook>. The intro
322 will show you what Moose is, and how it makes Perl 5 OO better.
324 The cookbook recipes on Moose basics will get you up to speed with
325 many of Moose's features quickly. Once you have an idea of what Moose
326 can do, you can use the API documentation to get more detail on
327 features which interest you.
329 =head2 Moose Extensions
331 The C<MooseX::> namespace is the official place to find Moose extensions.
332 These extensions can be found on the CPAN. The easiest way to find them
333 is to search for them (L<http://search.cpan.org/search?query=MooseX::>),
334 or to examine L<Task::Moose> which aims to keep an up-to-date, easily
335 installable list of Moose extensions.
339 Much of the Moose documentation has been translated into other languages.
345 Japanese docs can be found at
346 L<http://perldoc.perlassociation.org/pod/Moose-Doc-JA/index.html>. The
347 source POD files can be found in GitHub:
348 L<http://github.com/jpa/Moose-Doc-JA>
352 =head1 BUILDING CLASSES WITH MOOSE
354 Moose makes every attempt to provide as much convenience as possible during
355 class construction/definition, but still stay out of your way if you want it
356 to. Here are a few items to note when building classes with Moose.
358 When you C<use Moose>, Moose will set the class's parent class to
359 L<Moose::Object>, I<unless> the class using Moose already has a parent
360 class. In addition, specifying a parent with C<extends> will change the parent
363 Moose will also manage all attributes (including inherited ones) that are
364 defined with C<has>. And (assuming you call C<new>, which is inherited from
365 L<Moose::Object>) this includes properly initializing all instance slots,
366 setting defaults where appropriate, and performing any type constraint checking
369 =head1 PROVIDED METHODS
371 Moose provides a number of methods to all your classes, mostly through the
372 inheritance of L<Moose::Object>. There is however, one exception.
378 This is a method which provides access to the current class's metaclass.
382 =head1 EXPORTED FUNCTIONS
384 Moose will export a number of functions into the class's namespace which
385 may then be used to set up the class. These functions all work directly
386 on the current class.
390 =item B<extends (@superclasses)>
392 This function will set the superclass(es) for the current class.
394 This approach is recommended instead of C<use base>, because C<use base>
395 actually C<push>es onto the class's C<@ISA>, whereas C<extends> will
396 replace it. This is important to ensure that classes which do not have
397 superclasses still properly inherit from L<Moose::Object>.
399 Each superclass can be followed by a hash reference with options. Currently,
400 only L<-version|Class::MOP/Class Loading Options> is recognized:
402 extends 'My::Parent' => { -version => 0.01 },
403 'My::OtherParent' => { -version => 0.03 };
405 An exception will be thrown if the version requirements are not
408 =item B<with (@roles)>
410 This will apply a given set of C<@roles> to the local class.
412 Like with C<extends>, each specified role can be followed by a hash
413 reference with a L<-version|Class::MOP/Class Loading Options> option:
415 with 'My::Role' => { -version => 0.32 },
416 'My::Otherrole' => { -version => 0.23 };
418 The specified version requirements must be satisfied, otherwise an
419 exception will be thrown.
421 If your role takes options or arguments, they can be passed along in the
422 hash reference as well.
424 =item B<has $name|@$names =E<gt> %options>
426 This will install an attribute of a given C<$name> into the current class. If
427 the first parameter is an array reference, it will create an attribute for
428 every C<$name> in the list. The C<%options> are the same as those provided by
429 L<Class::MOP::Attribute>, in addition to the list below which are provided by
430 Moose (L<Moose::Meta::Attribute> to be more specific):
434 =item I<is =E<gt> 'rw'|'ro'>
436 The I<is> option accepts either I<rw> (for read/write) or I<ro> (for read
437 only). These will create either a read/write accessor or a read-only
438 accessor respectively, using the same name as the C<$name> of the attribute.
440 If you need more control over how your accessors are named, you can
441 use the L<reader|Class::MOP::Attribute/reader>,
442 L<writer|Class::MOP::Attribute/writer> and
443 L<accessor|Class::MOP::Attribute/accessor> options inherited from
444 L<Class::MOP::Attribute>, however if you use those, you won't need the
447 =item I<isa =E<gt> $type_name>
449 The I<isa> option uses Moose's type constraint facilities to set up runtime
450 type checking for this attribute. Moose will perform the checks during class
451 construction, and within any accessors. The C<$type_name> argument must be a
452 string. The string may be either a class name or a type defined using
453 Moose's type definition features. (Refer to L<Moose::Util::TypeConstraints>
454 for information on how to define a new type, and how to retrieve type meta-data).
456 =item I<coerce =E<gt> (1|0)>
458 This will attempt to use coercion with the supplied type constraint to change
459 the value passed into any accessors or constructors. You B<must> supply a type
460 constraint, and that type constraint B<must> define a coercion. See
461 L<Moose::Cookbook::Basics::Recipe5> for an example.
463 =item I<does =E<gt> $role_name>
465 This will accept the name of a role which the value stored in this attribute
466 is expected to have consumed.
468 =item I<required =E<gt> (1|0)>
470 This marks the attribute as being required. This means a value must be
471 supplied during class construction, I<or> the attribute must be lazy
472 and have either a default or a builder. Note that c<required> does not
473 say anything about the attribute's value, which can be C<undef>.
475 =item I<weak_ref =E<gt> (1|0)>
477 This will tell the class to store the value of this attribute as a weakened
478 reference. If an attribute is a weakened reference, it B<cannot> also be
481 =item I<lazy =E<gt> (1|0)>
483 This will tell the class to not create this slot until absolutely necessary.
484 If an attribute is marked as lazy it B<must> have a default supplied.
486 =item I<auto_deref =E<gt> (1|0)>
488 This tells the accessor to automatically dereference the value of this
489 attribute when called in list context. The accessor will still return a
490 reference when called in scalar context. If this behavior isn't desirable,
491 L<Moose::Meta::Attribute::Native::Trait::Array/elements> or
492 L<Moose::Meta::Attribute::Native::Trait::Hash/elements> may be a better
493 choice. The I<auto_deref> option is only legal if your I<isa> option is
494 either C<ArrayRef> or C<HashRef>.
496 =item I<trigger =E<gt> $code>
498 The I<trigger> option is a CODE reference which will be called after
499 the value of the attribute is set. The CODE ref is passed the
500 instance itself, the updated value, and the original value if the
501 attribute was already set.
503 You B<can> have a trigger on a read-only attribute.
505 B<NOTE:> Triggers will only fire when you B<assign> to the attribute,
506 either in the constructor, or using the writer. Default and built values will
507 B<not> cause the trigger to be fired.
509 =item I<handles =E<gt> ARRAY | HASH | REGEXP | ROLE | ROLETYPE | DUCKTYPE | CODE>
511 The I<handles> option provides Moose classes with automated delegation features.
512 This is a pretty complex and powerful option. It accepts many different option
513 formats, each with its own benefits and drawbacks.
515 B<NOTE:> The class being delegated to does not need to be a Moose based class,
516 which is why this feature is especially useful when wrapping non-Moose classes.
518 All I<handles> option formats share the following traits:
520 You cannot override a locally defined method with a delegated method; an
521 exception will be thrown if you try. That is to say, if you define C<foo> in
522 your class, you cannot override it with a delegated C<foo>. This is almost never
523 something you would want to do, and if it is, you should do it by hand and not
526 You cannot override any of the methods found in Moose::Object, or the C<BUILD>
527 and C<DEMOLISH> methods. These will not throw an exception, but will silently
528 move on to the next method in the list. My reasoning for this is that you would
529 almost never want to do this, since it usually breaks your class. As with
530 overriding locally defined methods, if you do want to do this, you should do it
531 manually, not with Moose.
533 You do not I<need> to have a reader (or accessor) for the attribute in order
534 to delegate to it. Moose will create a means of accessing the value for you,
535 however this will be several times B<less> efficient then if you had given
536 the attribute a reader (or accessor) to use.
538 Below is the documentation for each option format:
544 This is the most common usage for I<handles>. You basically pass a list of
545 method names to be delegated, and Moose will install a delegation method
550 This is the second most common usage for I<handles>. Instead of a list of
551 method names, you pass a HASH ref where each key is the method name you
552 want installed locally, and its value is the name of the original method
553 in the class being delegated to.
555 This can be very useful for recursive classes like trees. Here is a
556 quick example (soon to be expanded into a Moose::Cookbook recipe):
561 has 'node' => (is => 'rw', isa => 'Any');
566 default => sub { [] }
574 parent_node => 'node',
575 siblings => 'children',
579 In this example, the Tree package gets C<parent_node> and C<siblings> methods,
580 which delegate to the C<node> and C<children> methods (respectively) of the Tree
581 instance stored in the C<parent> slot.
583 You may also use an array reference to curry arguments to the original method.
587 handles => { set_foo => [ set => 'foo' ] },
590 # $self->set_foo(...) calls $self->thing->set('foo', ...)
592 The first element of the array reference is the original method name, and the
593 rest is a list of curried arguments.
597 The regexp option works very similar to the ARRAY option, except that it builds
598 the list of methods for you. It starts by collecting all possible methods of the
599 class being delegated to, then filters that list using the regexp supplied here.
601 B<NOTE:> An I<isa> option is required when using the regexp option format. This
602 is so that we can determine (at compile time) the method list from the class.
603 Without an I<isa> this is just not possible.
605 =item C<ROLE> or C<ROLETYPE>
607 With the role option, you specify the name of a role or a
608 L<role type|Moose::Meta::TypeConstraint::Role> whose "interface" then becomes
609 the list of methods to handle. The "interface" can be defined as; the methods
610 of the role and any required methods of the role. It should be noted that this
611 does B<not> include any method modifiers or generated attribute methods (which
612 is consistent with role composition).
616 With the duck type option, you pass a duck type object whose "interface" then
617 becomes the list of methods to handle. The "interface" can be defined as the
618 list of methods passed to C<duck_type> to create a duck type object. For more
619 information on C<duck_type> please check
620 L<Moose::Util::TypeConstraints>.
624 This is the option to use when you really want to do something funky. You should
625 only use it if you really know what you are doing, as it involves manual
628 This takes a code reference, which should expect two arguments. The first is the
629 attribute meta-object this I<handles> is attached to. The second is the
630 metaclass of the class being delegated to. It expects you to return a hash (not
631 a HASH ref) of the methods you want mapped.
635 =item I<metaclass =E<gt> $metaclass_name>
637 This tells the class to use a custom attribute metaclass for this particular
638 attribute. Custom attribute metaclasses are useful for extending the
639 capabilities of the I<has> keyword: they are the simplest way to extend the MOP,
640 but they are still a fairly advanced topic and too much to cover here. See
641 L<Moose::Cookbook::Meta::Recipe1> for more information.
643 See L<Metaclass and Trait Name Resolution> for details on how a metaclass name
644 is resolved to a class name.
646 =item I<traits =E<gt> [ @role_names ]>
648 This tells Moose to take the list of C<@role_names> and apply them to the
649 attribute meta-object. This is very similar to the I<metaclass> option, but
650 allows you to use more than one extension at a time.
652 See L<Metaclass and Trait Name Resolution> for details on how a trait name is
653 resolved to a role name.
655 Also see L<Moose::Cookbook::Meta::Recipe3> for a metaclass trait
658 =item I<builder> => Str
660 The value of this key is the name of the method that will be called to
661 obtain the value used to initialize the attribute. See the L<builder
662 option docs in Class::MOP::Attribute|Class::MOP::Attribute/builder>
663 and/or L<Moose::Cookbook::Basics::Recipe8> for more information.
665 =item I<default> => SCALAR | CODE
667 The value of this key is the default value which will initialize the attribute.
669 NOTE: If the value is a simple scalar (string or number), then it can
670 be just passed as is. However, if you wish to initialize it with a
671 HASH or ARRAY ref, then you need to wrap that inside a CODE reference.
672 See the L<default option docs in
673 Class::MOP::Attribute|Class::MOP::Attribute/default> for more
676 =item I<clearer> => Str
678 Creates a method allowing you to clear the value. See the L<clearer option
679 docs in Class::MOP::Attribute|Class::MOP::Attribute/clearer> for more
682 =item I<predicate> => Str
684 Creates a method to perform a basic test to see if a value has been set in the
685 attribute. See the L<predicate option docs in
686 Class::MOP::Attribute|Class::MOP::Attribute/predicate> for more information.
688 =item I<lazy_build> => (0|1)
690 Automatically define lazy => 1 as well as builder => "_build_$attr", clearer =>
691 "clear_$attr', predicate => 'has_$attr' unless they are already defined.
693 =item I<initializer> => Str
695 This may be a method name (referring to a method on the class with
696 this attribute) or a CODE ref. The initializer is used to set the
697 attribute value on an instance when the attribute is set during
698 instance initialization (but not when the value is being assigned
699 to). See the L<initializer option docs in
700 Class::MOP::Attribute|Class::MOP::Attribute/initializer> for more
703 =item I<documentation> => $string
705 An arbitrary string that can be retrieved later by calling C<<
706 $attr->documentation >>.
712 =item B<has +$name =E<gt> %options>
714 This is variation on the normal attribute creator C<has> which allows you to
715 clone and extend an attribute from a superclass or from a role. Here is an
716 example of the superclass usage:
724 default => 'Hello, I am a Foo'
732 has '+message' => (default => 'Hello I am My::Foo');
734 What is happening here is that B<My::Foo> is cloning the C<message> attribute
735 from its parent class B<Foo>, retaining the C<is =E<gt> 'rw'> and C<isa =E<gt>
736 'Str'> characteristics, but changing the value in C<default>.
738 Here is another example, but within the context of a role:
746 default => 'Hello, I am a Foo'
754 has '+message' => (default => 'Hello I am My::Foo');
756 In this case, we are basically taking the attribute which the role supplied
757 and altering it within the bounds of this feature.
759 Note that you can only extend an attribute from either a superclass or a role,
760 you cannot extend an attribute in a role that composes over an attribute from
763 Aside from where the attributes come from (one from superclass, the other
764 from a role), this feature works exactly the same. This feature is restricted
765 somewhat, so as to try and force at least I<some> sanity into it. You are only
766 allowed to change the following attributes:
772 Change the default value of an attribute.
776 Change whether the attribute attempts to coerce a value passed to it.
780 Change if the attribute is required to have a value.
782 =item I<documentation>
784 Change the documentation string associated with the attribute.
788 Change if the attribute lazily initializes the slot.
792 You I<are> allowed to change the type without restriction.
794 It is recommended that you use this freedom with caution. We used to
795 only allow for extension only if the type was a subtype of the parent's
796 type, but we felt that was too restrictive and is better left as a
801 You are allowed to B<add> a new C<handles> definition, but you are B<not>
802 allowed to I<change> one.
806 You are allowed to B<add> a new C<builder> definition, but you are B<not>
807 allowed to I<change> one.
811 You are allowed to B<add> a new C<metaclass> definition, but you are
812 B<not> allowed to I<change> one.
816 You are allowed to B<add> additional traits to the C<traits> definition.
817 These traits will be composed into the attribute, but preexisting traits
818 B<are not> overridden, or removed.
822 =item B<before $name|@names|\@names|qr/.../ =E<gt> sub { ... }>
824 =item B<after $name|@names|\@names|qr/.../ =E<gt> sub { ... }>
826 =item B<around $name|@names|\@names|qr/.../ =E<gt> sub { ... }>
828 These three items are syntactic sugar for the before, after, and around method
829 modifier features that L<Class::MOP> provides. More information on these may be
830 found in L<Moose::Manual::MethodModifiers> and the
831 L<Class::MOP::Class documentation|Class::MOP::Class/"Method Modifiers">.
835 The keyword C<super> is a no-op when called outside of an C<override> method. In
836 the context of an C<override> method, it will call the next most appropriate
837 superclass method with the same arguments as the original method.
839 =item B<override ($name, &sub)>
841 An C<override> method is a way of explicitly saying "I am overriding this
842 method from my superclass". You can call C<super> within this method, and
843 it will work as expected. The same thing I<can> be accomplished with a normal
844 method call and the C<SUPER::> pseudo-package; it is really your choice.
848 The keyword C<inner>, much like C<super>, is a no-op outside of the context of
849 an C<augment> method. You can think of C<inner> as being the inverse of
850 C<super>; the details of how C<inner> and C<augment> work is best described in
851 the L<Moose::Cookbook::Basics::Recipe6>.
853 =item B<augment ($name, &sub)>
855 An C<augment> method, is a way of explicitly saying "I am augmenting this
856 method from my superclass". Once again, the details of how C<inner> and
857 C<augment> work is best described in the L<Moose::Cookbook::Basics::Recipe6>.
861 This is the C<Carp::confess> function, and exported here because I use it
866 This is the C<Scalar::Util::blessed> function. It is exported here because I
867 use it all the time. It is highly recommended that this is used instead of
868 C<ref> anywhere you need to test for an object's class name.
874 When you use Moose, you can specify which metaclass to use:
876 use Moose -metaclass => 'My::Meta::Class';
878 You can also specify traits which will be applied to your metaclass:
880 use Moose -traits => 'My::Trait';
882 This is very similar to the attribute traits feature. When you do
883 this, your class's C<meta> object will have the specified traits
884 applied to it. See L<Metaclass and Trait Name Resolution> for more
887 =head2 Metaclass and Trait Name Resolution
889 By default, when given a trait name, Moose simply tries to load a
890 class of the same name. If such a class does not exist, it then looks
891 for for a class matching
892 B<Moose::Meta::$type::Custom::Trait::$trait_name>. The C<$type>
893 variable here will be one of B<Attribute> or B<Class>, depending on
894 what the trait is being applied to.
896 If a class with this long name exists, Moose checks to see if it has
897 the method C<register_implementation>. This method is expected to
898 return the I<real> class name of the trait. If there is no
899 C<register_implementation> method, it will fall back to using
900 B<Moose::Meta::$type::Custom::Trait::$trait> as the trait name.
902 The lookup method for metaclasses is the same, except that it looks
903 for a class matching B<Moose::Meta::$type::Custom::$metaclass_name>.
905 If all this is confusing, take a look at
906 L<Moose::Cookbook::Meta::Recipe3>, which demonstrates how to create an
909 =head1 UNIMPORTING FUNCTIONS
913 Moose offers a way to remove the keywords it exports, through the C<unimport>
914 method. You simply have to say C<no Moose> at the bottom of your code for this
915 to work. Here is an example:
920 has 'first_name' => (is => 'rw', isa => 'Str');
921 has 'last_name' => (is => 'rw', isa => 'Str');
925 $self->first_name . ' ' . $self->last_name
928 no Moose; # keywords are removed from the Person package
930 =head1 EXTENDING AND EMBEDDING MOOSE
932 To learn more about extending Moose, we recommend checking out the
933 "Extending" recipes in the L<Moose::Cookbook>, starting with
934 L<Moose::Cookbook::Extending::Recipe1>, which provides an overview of
935 all the different ways you might extend Moose.
937 =head2 B<< Moose->init_meta(for_class => $class, base_class => $baseclass, metaclass => $metaclass) >>
939 The C<init_meta> method sets up the metaclass object for the class
940 specified by C<for_class>. This method injects a a C<meta> accessor
941 into the class so you can get at this object. It also sets the class's
942 superclass to C<base_class>, with L<Moose::Object> as the default.
944 C<init_meta> returns the metaclass object for C<$class>.
946 You can specify an alternate metaclass with the C<metaclass> option.
948 For more detail on this topic, see L<Moose::Cookbook::Extending::Recipe2>.
950 This method used to be documented as a function which accepted
951 positional parameters. This calling style will still work for
952 backwards compatibility, but is deprecated.
956 Moose's C<import> method supports the L<Sub::Exporter> form of C<{into =E<gt> $pkg}>
957 and C<{into_level =E<gt> 1}>.
959 B<NOTE>: Doing this is more or less deprecated. Use L<Moose::Exporter>
960 instead, which lets you stack multiple C<Moose.pm>-alike modules
961 sanely. It handles getting the exported functions into the right place
964 =head2 B<throw_error>
966 An alias for C<confess>, used internally by Moose.
968 =head2 The MooseX:: namespace
970 Generally if you're writing an extension I<for> Moose itself you'll want
971 to put your extension in the C<MooseX::> namespace. This namespace is
972 specifically for extensions that make Moose better or different in some
973 fundamental way. It is traditionally B<not> for a package that just happens
974 to use Moose. This namespace follows from the examples of the C<LWPx::>
975 and C<DBIx::> namespaces that perform the same function for C<LWP> and C<DBI>
978 =head1 METACLASS COMPATIBILITY AND MOOSE
980 Metaclass compatibility is a thorny subject. You should start by
981 reading the "About Metaclass compatibility" section in the
984 Moose will attempt to resolve a few cases of metaclass incompatibility
985 when you set the superclasses for a class, in addition to the cases that
986 C<Class::MOP> handles.
988 Moose tries to determine if the metaclasses only "differ by roles". This
989 means that the parent and child's metaclass share a common ancestor in
990 their respective hierarchies, and that the subclasses under the common
991 ancestor are only different because of role applications. This case is
992 actually fairly common when you mix and match various C<MooseX::*>
993 modules, many of which apply roles to the metaclass.
995 If the parent and child do differ by roles, Moose replaces the
996 metaclass in the child with a newly created metaclass. This metaclass
997 is a subclass of the parent's metaclass which does all of the roles that
998 the child's metaclass did before being replaced. Effectively, this
999 means the new metaclass does all of the roles done by both the
1000 parent's and child's original metaclasses.
1002 Ultimately, this is all transparent to you except in the case of an
1003 unresolvable conflict.
1011 It should be noted that C<super> and C<inner> B<cannot> be used in the same
1012 method. However, they may be combined within the same class hierarchy; see
1013 F<t/014_override_augment_inner_super.t> for an example.
1015 The reason for this is that C<super> is only valid within a method
1016 with the C<override> modifier, and C<inner> will never be valid within an
1017 C<override> method. In fact, C<augment> will skip over any C<override> methods
1018 when searching for its appropriate C<inner>.
1020 This might seem like a restriction, but I am of the opinion that keeping these
1021 two features separate (yet interoperable) actually makes them easy to use, since
1022 their behavior is then easier to predict. Time will tell whether I am right or
1023 not (UPDATE: so far so good).
1029 We offer both a mailing list and a very active IRC channel.
1031 The mailing list is L<moose@perl.org>. You must be subscribed to send
1032 a message. To subscribe, send an empty message to
1033 L<moose-subscribe@perl.org>
1035 You can also visit us at C<#moose> on L<irc://irc.perl.org/#moose>
1036 This channel is quite active, and questions at all levels (on Moose-related
1037 topics ;) are welcome.
1039 =head1 ACKNOWLEDGEMENTS
1043 =item I blame Sam Vilain for introducing me to the insanity that is meta-models.
1045 =item I blame Audrey Tang for then encouraging my meta-model habit in #perl6.
1047 =item Without Yuval "nothingmuch" Kogman this module would not be possible,
1048 and it certainly wouldn't have this name ;P
1050 =item The basis of the TypeContraints module was Rob Kinyon's idea
1051 originally, I just ran with it.
1053 =item Thanks to mst & chansen and the whole #moose posse for all the
1054 early ideas/feature-requests/encouragement/bug-finding.
1056 =item Thanks to David "Theory" Wheeler for meta-discussions and spelling fixes.
1064 =item L<http://www.iinteractive.com/moose>
1066 This is the official web home of Moose, it contains links to our public git repository
1067 as well as links to a number of talks and articles on Moose and Moose related
1070 =item The Moose is flying, a tutorial by Randal Schwartz
1072 Part 1 - L<http://www.stonehenge.com/merlyn/LinuxMag/col94.html>
1074 Part 2 - L<http://www.stonehenge.com/merlyn/LinuxMag/col95.html>
1076 =item Several Moose extension modules in the C<MooseX::> namespace.
1078 See L<http://search.cpan.org/search?query=MooseX::> for extensions.
1080 =item Moose stats on ohloh.net - L<http://www.ohloh.net/projects/moose>
1088 =item The Art of the MetaObject Protocol
1090 I mention this in the L<Class::MOP> docs too, as this book was critical in
1091 the development of both modules and is highly recommended.
1099 =item L<http://www.cs.utah.edu/plt/publications/oopsla04-gff.pdf>
1101 This paper (suggested by lbr on #moose) was what lead to the implementation
1102 of the C<super>/C<override> and C<inner>/C<augment> features. If you really
1103 want to understand them, I suggest you read this.
1109 All complex software has bugs lurking in it, and this module is no
1112 Please report any bugs to C<bug-moose@rt.cpan.org>, or through the web
1113 interface at L<http://rt.cpan.org>.
1115 You can also discuss feature requests or possible bugs on the Moose mailing
1116 list (moose@perl.org) or on IRC at L<irc://irc.perl.org/#moose>.
1118 =head1 FEATURE REQUESTS
1120 We are very strict about what features we add to the Moose core, especially
1121 the user-visible features. Instead we have made sure that the underlying
1122 meta-system of Moose is as extensible as possible so that you can add your
1123 own features easily.
1125 That said, occasionally there is a feature needed in the meta-system
1126 to support your planned extension, in which case you should either
1127 email the mailing list (moose@perl.org) or join us on IRC at
1128 L<irc://irc.perl.org/#moose> to discuss. The
1129 L<Moose::Manual::Contributing> has more detail about how and when you
1134 There are only a few people with the rights to release a new version
1135 of Moose. The Moose Cabal are the people to go to with questions regarding
1136 the wider purview of Moose. They help maintain not just the code
1137 but the community as well.
1139 Stevan (stevan) Little E<lt>stevan@iinteractive.comE<gt>
1141 Jesse (doy) Luehrs E<lt>doy at tozt dot netE<gt>
1143 Yuval (nothingmuch) Kogman
1145 Shawn (sartak) Moore E<lt>sartak@bestpractical.comE<gt>
1147 Hans Dieter (confound) Pearcey E<lt>hdp@pobox.comE<gt>
1149 Chris (perigrin) Prather
1151 Florian Ragwitz E<lt>rafl@debian.orgE<gt>
1153 Dave (autarch) Rolsky E<lt>autarch@urth.orgE<gt>
1159 Adam (Alias) Kennedy
1161 Anders (Debolaz) Nor Berle
1163 Chris (perigrin) Prather
1165 Christian (chansen) Hansen
1169 Dylan Hardison (doc fixes)
1171 Eric (ewilhelm) Wilhelm
1175 Florian (rafl) Ragwitz
1177 Guillermo (groditi) Roditi
1183 Jess (castaway) Robinson
1185 Jonathan (jrockway) Rockway
1189 Nathan (kolibrie) Gray
1191 Paul (frodwith) Driver
1193 Piotr (dexter) Roszatycki
1197 Robert (phaylon) Sedlacek
1201 Sam (mugwump) Vilain
1203 Scott (konobi) McWhirter
1205 Shawn (Sartak) Moore
1207 Shlomi (rindolf) Fish
1211 Wallace (wreis) Reis
1213 ... and many other #moose folks