8 $VERSION = eval $VERSION;
9 our $AUTHORITY = 'cpan:STEVAN';
11 use Scalar::Util 'blessed';
14 use Moose::Deprecated;
19 use Moose::Meta::Class;
20 use Moose::Meta::TypeConstraint;
21 use Moose::Meta::TypeCoercion;
22 use Moose::Meta::Attribute;
23 use Moose::Meta::Instance;
27 use Moose::Meta::Role;
28 use Moose::Meta::Role::Composite;
29 use Moose::Meta::Role::Application;
30 use Moose::Meta::Role::Application::RoleSummation;
31 use Moose::Meta::Role::Application::ToClass;
32 use Moose::Meta::Role::Application::ToRole;
33 use Moose::Meta::Role::Application::ToInstance;
35 use Moose::Util::TypeConstraints;
38 use Moose::Meta::Attribute::Native;
49 Moose->throw_error("Must derive at least one class") unless @_;
51 # this checks the metaclass to make sure
52 # it is correct, sometimes it can get out
53 # of sync when the classes are being built
54 $meta->superclasses(@_);
58 Moose::Util::apply_all_roles(shift, @_);
65 Moose->throw_error('Usage: has \'name\' => ( key => value, ... )')
68 my %options = ( definition_context => Moose::Util::_caller_info(), @_ );
69 my $attrs = ( ref($name) eq 'ARRAY' ) ? $name : [ ($name) ];
70 $meta->add_attribute( $_, %options ) for @$attrs;
74 Moose::Util::add_method_modifier(shift, 'before', \@_);
78 Moose::Util::add_method_modifier(shift, 'after', \@_);
82 Moose::Util::add_method_modifier(shift, 'around', \@_);
90 # This check avoids a recursion loop - see
91 # t/100_bugs/020_super_recursion.t
92 return if defined $SUPER_PACKAGE && $SUPER_PACKAGE ne caller();
93 return unless $SUPER_BODY; $SUPER_BODY->(@SUPER_ARGS);
98 my ( $name, $method ) = @_;
99 $meta->add_override_method_modifier( $name => $method );
104 our ( %INNER_BODY, %INNER_ARGS );
106 if ( my $body = $INNER_BODY{$pkg} ) {
107 my @args = @{ $INNER_ARGS{$pkg} };
108 local $INNER_ARGS{$pkg};
109 local $INNER_BODY{$pkg};
110 return $body->(@args);
118 my ( $name, $method ) = @_;
119 $meta->add_augment_method_modifier( $name => $method );
122 Moose::Exporter->setup_import_methods(
124 qw( extends with has before after around override augment )
129 \&Scalar::Util::blessed,
134 # This used to be called as a function. This hack preserves
135 # backwards compatibility.
136 if ( $_[0] ne __PACKAGE__ ) {
137 Moose::Deprecated::deprecated(
138 feature => 'Moose::init_meta',
139 message => 'Calling Moose::init_meta as a function is deprecated',
142 return __PACKAGE__->init_meta(
152 my $class = $args{for_class}
153 or Moose->throw_error("Cannot call init_meta without specifying a for_class");
154 my $base_class = $args{base_class} || 'Moose::Object';
155 my $metaclass = $args{metaclass} || 'Moose::Meta::Class';
157 Moose->throw_error("The Metaclass $metaclass must be a subclass of Moose::Meta::Class.")
158 unless $metaclass->isa('Moose::Meta::Class');
160 # make a subtype for each Moose class
162 unless find_type_constraint($class);
166 if ( $meta = Class::MOP::get_metaclass_by_name($class) ) {
167 unless ( $meta->isa("Moose::Meta::Class") ) {
168 my $error_message = "$class already has a metaclass, but it does not inherit $metaclass ($meta).";
169 if ( $meta->isa('Moose::Meta::Role') ) {
170 Moose->throw_error($error_message . ' You cannot make the same thing a role and a class. Remove either Moose or Moose::Role.');
172 Moose->throw_error($error_message);
178 # now we check whether our ancestors have metaclass, and if so borrow that
179 my ( undef, @isa ) = @{ mro::get_linear_isa($class) };
181 foreach my $ancestor ( @isa ) {
182 my $ancestor_meta = Class::MOP::get_metaclass_by_name($ancestor) || next;
184 my $ancestor_meta_class = $ancestor_meta->_real_ref_name;
186 # if we have an ancestor metaclass that inherits $metaclass, we use
187 # that. This is like _fix_metaclass_incompatibility, but we can do it now.
189 # the case of having an ancestry is not very common, but arises in
191 unless ( $metaclass->isa( $ancestor_meta_class ) ) {
192 if ( $ancestor_meta_class->isa($metaclass) ) {
193 $metaclass = $ancestor_meta_class;
198 $meta = $metaclass->initialize($class);
201 unless ( $meta->has_method("meta") ) { # don't overwrite
202 # also check for inherited non moose 'meta' method?
203 # FIXME also skip this if the user requested by passing an option
204 $meta->_add_meta_method;
207 # make sure they inherit from Moose::Object
208 $meta->superclasses($base_class)
209 unless $meta->superclasses();
214 # This may be used in some older MooseX extensions.
216 goto &Moose::Exporter::_get_caller;
219 ## make 'em all immutable
222 inline_constructor => 1,
223 constructor_name => "_new",
224 # these are Class::MOP accessors, so they need inlining
225 inline_accessors => 1
226 ) for grep { $_->is_mutable }
229 Moose::Meta::Attribute
231 Moose::Meta::Instance
233 Moose::Meta::TypeCoercion
234 Moose::Meta::TypeCoercion::Union
237 Moose::Meta::Method::Accessor
238 Moose::Meta::Method::Constructor
239 Moose::Meta::Method::Destructor
240 Moose::Meta::Method::Overridden
241 Moose::Meta::Method::Augmented
244 Moose::Meta::Role::Attribute
245 Moose::Meta::Role::Method
246 Moose::Meta::Role::Method::Required
247 Moose::Meta::Role::Method::Conflicting
249 Moose::Meta::Role::Composite
251 Moose::Meta::Role::Application
252 Moose::Meta::Role::Application::RoleSummation
253 Moose::Meta::Role::Application::ToClass
254 Moose::Meta::Role::Application::ToRole
255 Moose::Meta::Role::Application::ToInstance
258 Moose::Meta::Mixin::AttributeCore->meta->make_immutable(
259 inline_constructor => 0,
260 constructor_name => undef,
271 Moose - A postmodern object system for Perl 5
276 use Moose; # automatically turns on strict and warnings
278 has 'x' => (is => 'rw', isa => 'Int');
279 has 'y' => (is => 'rw', isa => 'Int');
292 has 'z' => (is => 'rw', isa => 'Int');
294 after 'clear' => sub {
301 Moose is an extension of the Perl 5 object system.
303 The main goal of Moose is to make Perl 5 Object Oriented programming
304 easier, more consistent and less tedious. With Moose you can to think
305 more about what you want to do and less about the mechanics of OOP.
307 Additionally, Moose is built on top of L<Class::MOP>, which is a
308 metaclass system for Perl 5. This means that Moose not only makes
309 building normal Perl 5 objects better, but it provides the power of
310 metaclass programming as well.
314 If you're new to Moose, the best place to start is the
315 L<Moose::Manual> docs, followed by the L<Moose::Cookbook>. The intro
316 will show you what Moose is, and how it makes Perl 5 OO better.
318 The cookbook recipes on Moose basics will get you up to speed with
319 many of Moose's features quickly. Once you have an idea of what Moose
320 can do, you can use the API documentation to get more detail on
321 features which interest you.
323 =head2 Moose Extensions
325 The C<MooseX::> namespace is the official place to find Moose extensions.
326 These extensions can be found on the CPAN. The easiest way to find them
327 is to search for them (L<http://search.cpan.org/search?query=MooseX::>),
328 or to examine L<Task::Moose> which aims to keep an up-to-date, easily
329 installable list of Moose extensions.
333 Much of the Moose documentation has been translated into other languages.
339 Japanese docs can be found at
340 L<http://perldoc.perlassociation.org/pod/Moose-Doc-JA/index.html>. The
341 source POD files can be found in GitHub:
342 L<http://github.com/jpa/Moose-Doc-JA>
346 =head1 BUILDING CLASSES WITH MOOSE
348 Moose makes every attempt to provide as much convenience as possible during
349 class construction/definition, but still stay out of your way if you want it
350 to. Here are a few items to note when building classes with Moose.
352 When you C<use Moose>, Moose will set the class's parent class to
353 L<Moose::Object>, I<unless> the class using Moose already has a parent
354 class. In addition, specifying a parent with C<extends> will change the parent
357 Moose will also manage all attributes (including inherited ones) that are
358 defined with C<has>. And (assuming you call C<new>, which is inherited from
359 L<Moose::Object>) this includes properly initializing all instance slots,
360 setting defaults where appropriate, and performing any type constraint checking
363 =head1 PROVIDED METHODS
365 Moose provides a number of methods to all your classes, mostly through the
366 inheritance of L<Moose::Object>. There is however, one exception.
372 This is a method which provides access to the current class's metaclass.
376 =head1 EXPORTED FUNCTIONS
378 Moose will export a number of functions into the class's namespace which
379 may then be used to set up the class. These functions all work directly
380 on the current class.
384 =item B<extends (@superclasses)>
386 This function will set the superclass(es) for the current class.
388 This approach is recommended instead of C<use base>, because C<use base>
389 actually C<push>es onto the class's C<@ISA>, whereas C<extends> will
390 replace it. This is important to ensure that classes which do not have
391 superclasses still properly inherit from L<Moose::Object>.
393 Each superclass can be followed by a hash reference with options. Currently,
394 only L<-version|Class::MOP/Class Loading Options> is recognized:
396 extends 'My::Parent' => { -version => 0.01 },
397 'My::OtherParent' => { -version => 0.03 };
399 An exception will be thrown if the version requirements are not
402 =item B<with (@roles)>
404 This will apply a given set of C<@roles> to the local class.
406 Like with C<extends>, each specified role can be followed by a hash
407 reference with a L<-version|Class::MOP/Class Loading Options> option:
409 with 'My::Role' => { -version => 0.32 },
410 'My::Otherrole' => { -version => 0.23 };
412 The specified version requirements must be satisfied, otherwise an
413 exception will be thrown.
415 If your role takes options or arguments, they can be passed along in the
416 hash reference as well.
418 =item B<has $name|@$names =E<gt> %options>
420 This will install an attribute of a given C<$name> into the current class. If
421 the first parameter is an array reference, it will create an attribute for
422 every C<$name> in the list. The C<%options> are the same as those provided by
423 L<Class::MOP::Attribute>, in addition to the list below which are provided by
424 Moose (L<Moose::Meta::Attribute> to be more specific):
428 =item I<is =E<gt> 'rw'|'ro'>
430 The I<is> option accepts either I<rw> (for read/write) or I<ro> (for read
431 only). These will create either a read/write accessor or a read-only
432 accessor respectively, using the same name as the C<$name> of the attribute.
434 If you need more control over how your accessors are named, you can
435 use the L<reader|Class::MOP::Attribute/reader>,
436 L<writer|Class::MOP::Attribute/writer> and
437 L<accessor|Class::MOP::Attribute/accessor> options inherited from
438 L<Class::MOP::Attribute>, however if you use those, you won't need the
441 =item I<isa =E<gt> $type_name>
443 The I<isa> option uses Moose's type constraint facilities to set up runtime
444 type checking for this attribute. Moose will perform the checks during class
445 construction, and within any accessors. The C<$type_name> argument must be a
446 string. The string may be either a class name or a type defined using
447 Moose's type definition features. (Refer to L<Moose::Util::TypeConstraints>
448 for information on how to define a new type, and how to retrieve type meta-data).
450 =item I<coerce =E<gt> (1|0)>
452 This will attempt to use coercion with the supplied type constraint to change
453 the value passed into any accessors or constructors. You B<must> supply a type
454 constraint, and that type constraint B<must> define a coercion. See
455 L<Moose::Cookbook::Basics::Recipe5> for an example.
457 =item I<does =E<gt> $role_name>
459 This will accept the name of a role which the value stored in this attribute
460 is expected to have consumed.
462 =item I<required =E<gt> (1|0)>
464 This marks the attribute as being required. This means a value must be
465 supplied during class construction, I<or> the attribute must be lazy
466 and have either a default or a builder. Note that c<required> does not
467 say anything about the attribute's value, which can be C<undef>.
469 =item I<weak_ref =E<gt> (1|0)>
471 This will tell the class to store the value of this attribute as a weakened
472 reference. If an attribute is a weakened reference, it B<cannot> also be
475 =item I<lazy =E<gt> (1|0)>
477 This will tell the class to not create this slot until absolutely necessary.
478 If an attribute is marked as lazy it B<must> have a default supplied.
480 =item I<auto_deref =E<gt> (1|0)>
482 This tells the accessor to automatically dereference the value of this
483 attribute when called in list context. The accessor will still return a
484 reference when called in scalar context. If this behavior isn't desirable,
485 L<Moose::Meta::Attribute::Native::Trait::Array/elements> or
486 L<Moose::Meta::Attribute::Native::Trait::Hash/elements> may be a better
487 choice. The I<auto_deref> option is only legal if your I<isa> option is
488 either C<ArrayRef> or C<HashRef>.
490 =item I<trigger =E<gt> $code>
492 The I<trigger> option is a CODE reference which will be called after
493 the value of the attribute is set. The CODE ref is passed the
494 instance itself, the updated value, and the original value if the
495 attribute was already set.
497 You B<can> have a trigger on a read-only attribute.
499 B<NOTE:> Triggers will only fire when you B<assign> to the attribute,
500 either in the constructor, or using the writer. Default and built values will
501 B<not> cause the trigger to be fired.
503 =item I<handles =E<gt> ARRAY | HASH | REGEXP | ROLE | ROLETYPE | DUCKTYPE | CODE>
505 The I<handles> option provides Moose classes with automated delegation features.
506 This is a pretty complex and powerful option. It accepts many different option
507 formats, each with its own benefits and drawbacks.
509 B<NOTE:> The class being delegated to does not need to be a Moose based class,
510 which is why this feature is especially useful when wrapping non-Moose classes.
512 All I<handles> option formats share the following traits:
514 You cannot override a locally defined method with a delegated method; an
515 exception will be thrown if you try. That is to say, if you define C<foo> in
516 your class, you cannot override it with a delegated C<foo>. This is almost never
517 something you would want to do, and if it is, you should do it by hand and not
520 You cannot override any of the methods found in Moose::Object, or the C<BUILD>
521 and C<DEMOLISH> methods. These will not throw an exception, but will silently
522 move on to the next method in the list. My reasoning for this is that you would
523 almost never want to do this, since it usually breaks your class. As with
524 overriding locally defined methods, if you do want to do this, you should do it
525 manually, not with Moose.
527 You do not I<need> to have a reader (or accessor) for the attribute in order
528 to delegate to it. Moose will create a means of accessing the value for you,
529 however this will be several times B<less> efficient then if you had given
530 the attribute a reader (or accessor) to use.
532 Below is the documentation for each option format:
538 This is the most common usage for I<handles>. You basically pass a list of
539 method names to be delegated, and Moose will install a delegation method
544 This is the second most common usage for I<handles>. Instead of a list of
545 method names, you pass a HASH ref where each key is the method name you
546 want installed locally, and its value is the name of the original method
547 in the class being delegated to.
549 This can be very useful for recursive classes like trees. Here is a
550 quick example (soon to be expanded into a Moose::Cookbook recipe):
555 has 'node' => (is => 'rw', isa => 'Any');
560 default => sub { [] }
568 parent_node => 'node',
569 siblings => 'children',
573 In this example, the Tree package gets C<parent_node> and C<siblings> methods,
574 which delegate to the C<node> and C<children> methods (respectively) of the Tree
575 instance stored in the C<parent> slot.
577 You may also use an array reference to curry arguments to the original method.
581 handles => { set_foo => [ set => 'foo' ] },
584 # $self->set_foo(...) calls $self->thing->set('foo', ...)
586 The first element of the array reference is the original method name, and the
587 rest is a list of curried arguments.
591 The regexp option works very similar to the ARRAY option, except that it builds
592 the list of methods for you. It starts by collecting all possible methods of the
593 class being delegated to, then filters that list using the regexp supplied here.
595 B<NOTE:> An I<isa> option is required when using the regexp option format. This
596 is so that we can determine (at compile time) the method list from the class.
597 Without an I<isa> this is just not possible.
599 =item C<ROLE> or C<ROLETYPE>
601 With the role option, you specify the name of a role or a
602 L<role type|Moose::Meta::TypeConstraint::Role> whose "interface" then becomes
603 the list of methods to handle. The "interface" can be defined as; the methods
604 of the role and any required methods of the role. It should be noted that this
605 does B<not> include any method modifiers or generated attribute methods (which
606 is consistent with role composition).
610 With the duck type option, you pass a duck type object whose "interface" then
611 becomes the list of methods to handle. The "interface" can be defined as; the
612 list of methods passed to C<duck_type> to create a duck type object. For more
613 information on C<duck_type> please check
614 L<Moose::Util::TypeConstraints>.
618 This is the option to use when you really want to do something funky. You should
619 only use it if you really know what you are doing, as it involves manual
622 This takes a code reference, which should expect two arguments. The first is the
623 attribute meta-object this I<handles> is attached to. The second is the
624 metaclass of the class being delegated to. It expects you to return a hash (not
625 a HASH ref) of the methods you want mapped.
629 =item I<metaclass =E<gt> $metaclass_name>
631 This tells the class to use a custom attribute metaclass for this particular
632 attribute. Custom attribute metaclasses are useful for extending the
633 capabilities of the I<has> keyword: they are the simplest way to extend the MOP,
634 but they are still a fairly advanced topic and too much to cover here, see
635 L<Moose::Cookbook::Meta::Recipe1> for more information.
637 See L<Metaclass and Trait Name Resolution> for details on how a metaclass name
638 is resolved to a class name.
640 =item I<traits =E<gt> [ @role_names ]>
642 This tells Moose to take the list of C<@role_names> and apply them to the
643 attribute meta-object. This is very similar to the I<metaclass> option, but
644 allows you to use more than one extension at a time.
646 See L<Metaclass and Trait Name Resolution> for details on how a trait name is
647 resolved to a role name.
649 Also see L<Moose::Cookbook::Meta::Recipe3> for a metaclass trait
652 =item I<builder> => Str
654 The value of this key is the name of the method that will be called to
655 obtain the value used to initialize the attribute. See the L<builder
656 option docs in Class::MOP::Attribute|Class::MOP::Attribute/builder>
657 and/or L<Moose::Cookbook::Basics::Recipe8> for more information.
659 =item I<default> => SCALAR | CODE
661 The value of this key is the default value which will initialize the attribute.
663 NOTE: If the value is a simple scalar (string or number), then it can
664 be just passed as is. However, if you wish to initialize it with a
665 HASH or ARRAY ref, then you need to wrap that inside a CODE reference.
666 See the L<default option docs in
667 Class::MOP::Attribute|Class::MOP::Attribute/default> for more
670 =item I<clearer> => Str
672 Creates a method allowing you to clear the value, see the L<clearer option
673 docs in Class::MOP::Attribute|Class::MOP::Attribute/clearer> for more
676 =item I<predicate> => Str
678 Creates a method to perform a basic test to see if a value has been set in the
679 attribute, see the L<predicate option docs in
680 Class::MOP::Attribute|Class::MOP::Attribute/predicate> for more information.
682 =item I<lazy_build> => (0|1)
684 Automatically define lazy => 1 as well as builder => "_build_$attr", clearer =>
685 "clear_$attr', predicate => 'has_$attr' unless they are already defined.
687 =item I<initializer> => Str
689 This may be a method name (referring to a method on the class with
690 this attribute) or a CODE ref. The initializer is used to set the
691 attribute value on an instance when the attribute is set during
692 instance initialization (but not when the value is being assigned
693 to). See the L<initializer option docs in
694 Class::MOP::Attribute|Class::MOP::Attribute/initializer> for more
697 =item I<documentation> => $string
699 An arbitrary string that can be retrieved later by calling C<<
700 $attr->documentation >>.
706 =item B<has +$name =E<gt> %options>
708 This is variation on the normal attribute creator C<has> which allows you to
709 clone and extend an attribute from a superclass or from a role. Here is an
710 example of the superclass usage:
718 default => 'Hello, I am a Foo'
726 has '+message' => (default => 'Hello I am My::Foo');
728 What is happening here is that B<My::Foo> is cloning the C<message> attribute
729 from its parent class B<Foo>, retaining the C<is =E<gt> 'rw'> and C<isa =E<gt>
730 'Str'> characteristics, but changing the value in C<default>.
732 Here is another example, but within the context of a role:
740 default => 'Hello, I am a Foo'
748 has '+message' => (default => 'Hello I am My::Foo');
750 In this case, we are basically taking the attribute which the role supplied
751 and altering it within the bounds of this feature.
753 Note that you can only extend an attribute from either a superclass or a role,
754 you cannot extend an attribute in a role that composes over an attribute from
757 Aside from where the attributes come from (one from superclass, the other
758 from a role), this feature works exactly the same. This feature is restricted
759 somewhat, so as to try and force at least I<some> sanity into it. You are only
760 allowed to change the following attributes:
766 Change the default value of an attribute.
770 Change whether the attribute attempts to coerce a value passed to it.
774 Change if the attribute is required to have a value.
776 =item I<documentation>
778 Change the documentation string associated with the attribute.
782 Change if the attribute lazily initializes the slot.
786 You I<are> allowed to change the type without restriction.
788 It is recommended that you use this freedom with caution. We used to
789 only allow for extension only if the type was a subtype of the parent's
790 type, but we felt that was too restrictive and is better left as a
795 You are allowed to B<add> a new C<handles> definition, but you are B<not>
796 allowed to I<change> one.
800 You are allowed to B<add> a new C<builder> definition, but you are B<not>
801 allowed to I<change> one.
805 You are allowed to B<add> a new C<metaclass> definition, but you are
806 B<not> allowed to I<change> one.
810 You are allowed to B<add> additional traits to the C<traits> definition.
811 These traits will be composed into the attribute, but preexisting traits
812 B<are not> overridden, or removed.
816 =item B<before $name|@names|\@names|qr/.../ =E<gt> sub { ... }>
818 =item B<after $name|@names|\@names|qr/.../ =E<gt> sub { ... }>
820 =item B<around $name|@names|\@names|qr/.../ =E<gt> sub { ... }>
822 These three items are syntactic sugar for the before, after, and around method
823 modifier features that L<Class::MOP> provides. More information on these may be
824 found in L<Moose::Manual::MethodModifiers> and the
825 L<Class::MOP::Class documentation|Class::MOP::Class/"Method Modifiers">.
829 The keyword C<super> is a no-op when called outside of an C<override> method. In
830 the context of an C<override> method, it will call the next most appropriate
831 superclass method with the same arguments as the original method.
833 =item B<override ($name, &sub)>
835 An C<override> method is a way of explicitly saying "I am overriding this
836 method from my superclass". You can call C<super> within this method, and
837 it will work as expected. The same thing I<can> be accomplished with a normal
838 method call and the C<SUPER::> pseudo-package; it is really your choice.
842 The keyword C<inner>, much like C<super>, is a no-op outside of the context of
843 an C<augment> method. You can think of C<inner> as being the inverse of
844 C<super>; the details of how C<inner> and C<augment> work is best described in
845 the L<Moose::Cookbook::Basics::Recipe6>.
847 =item B<augment ($name, &sub)>
849 An C<augment> method, is a way of explicitly saying "I am augmenting this
850 method from my superclass". Once again, the details of how C<inner> and
851 C<augment> work is best described in the L<Moose::Cookbook::Basics::Recipe6>.
855 This is the C<Carp::confess> function, and exported here because I use it
860 This is the C<Scalar::Util::blessed> function, it is exported here because I
861 use it all the time. It is highly recommended that this is used instead of
862 C<ref> anywhere you need to test for an object's class name.
868 When you use Moose, you can specify which metaclass to use:
870 use Moose -metaclass => 'My::Meta::Class';
872 You can also specify traits which will be applied to your metaclass:
874 use Moose -traits => 'My::Trait';
876 This is very similar to the attribute traits feature. When you do
877 this, your class's C<meta> object will have the specified traits
878 applied to it. See L<Metaclass and Trait Name Resolution> for more
881 =head2 Metaclass and Trait Name Resolution
883 By default, when given a trait name, Moose simply tries to load a
884 class of the same name. If such a class does not exist, it then looks
885 for for a class matching
886 B<Moose::Meta::$type::Custom::Trait::$trait_name>. The C<$type>
887 variable here will be one of B<Attribute> or B<Class>, depending on
888 what the trait is being applied to.
890 If a class with this long name exists, Moose checks to see if it has
891 the method C<register_implementation>. This method is expected to
892 return the I<real> class name of the trait. If there is no
893 C<register_implementation> method, it will fall back to using
894 B<Moose::Meta::$type::Custom::Trait::$trait> as the trait name.
896 The lookup method for metaclasses is the same, except that it looks
897 for a class matching B<Moose::Meta::$type::Custom::$metaclass_name>.
899 If all this is confusing, take a look at
900 L<Moose::Cookbook::Meta::Recipe3>, which demonstrates how to create an
903 =head1 UNIMPORTING FUNCTIONS
907 Moose offers a way to remove the keywords it exports, through the C<unimport>
908 method. You simply have to say C<no Moose> at the bottom of your code for this
909 to work. Here is an example:
914 has 'first_name' => (is => 'rw', isa => 'Str');
915 has 'last_name' => (is => 'rw', isa => 'Str');
919 $self->first_name . ' ' . $self->last_name
922 no Moose; # keywords are removed from the Person package
924 =head1 EXTENDING AND EMBEDDING MOOSE
926 To learn more about extending Moose, we recommend checking out the
927 "Extending" recipes in the L<Moose::Cookbook>, starting with
928 L<Moose::Cookbook::Extending::Recipe1>, which provides an overview of
929 all the different ways you might extend Moose.
931 =head2 B<< Moose->init_meta(for_class => $class, base_class => $baseclass, metaclass => $metaclass) >>
933 The C<init_meta> method sets up the metaclass object for the class
934 specified by C<for_class>. This method injects a a C<meta> accessor
935 into the class so you can get at this object. It also sets the class's
936 superclass to C<base_class>, with L<Moose::Object> as the default.
938 C<init_meta> returns the metaclass object for C<$class>.
940 You can specify an alternate metaclass with the C<metaclass> option.
942 For more detail on this topic, see L<Moose::Cookbook::Extending::Recipe2>.
944 This method used to be documented as a function which accepted
945 positional parameters. This calling style will still work for
946 backwards compatibility, but is deprecated.
950 Moose's C<import> method supports the L<Sub::Exporter> form of C<{into =E<gt> $pkg}>
951 and C<{into_level =E<gt> 1}>.
953 B<NOTE>: Doing this is more or less deprecated. Use L<Moose::Exporter>
954 instead, which lets you stack multiple C<Moose.pm>-alike modules
955 sanely. It handles getting the exported functions into the right place
958 =head2 B<throw_error>
960 An alias for C<confess>, used by internally by Moose.
962 =head2 The MooseX:: namespace
964 Generally if you're writing an extension I<for> Moose itself you'll want
965 to put your extension in the C<MooseX::> namespace. This namespace is
966 specifically for extensions that make Moose better or different in some
967 fundamental way. It is traditionally B<not> for a package that just happens
968 to use Moose. This namespace follows from the examples of the C<LWPx::>
969 and C<DBIx::> namespaces that perform the same function for C<LWP> and C<DBI>
972 =head1 METACLASS COMPATIBILITY AND MOOSE
974 Metaclass compatibility is a thorny subject. You should start by
975 reading the "About Metaclass compatibility" section in the
978 Moose will attempt to resolve a few cases of metaclass incompatibility
979 when you set the superclasses for a class, in addition to the cases that
980 C<Class::MOP> handles.
982 Moose tries to determine if the metaclasses only "differ by roles". This
983 means that the parent and child's metaclass share a common ancestor in
984 their respective hierarchies, and that the subclasses under the common
985 ancestor are only different because of role applications. This case is
986 actually fairly common when you mix and match various C<MooseX::*>
987 modules, many of which apply roles to the metaclass.
989 If the parent and child do differ by roles, Moose replaces the
990 metaclass in the child with a newly created metaclass. This metaclass
991 is a subclass of the parent's metaclass, does all of the roles that
992 the child's metaclass did before being replaced. Effectively, this
993 means the new metaclass does all of the roles done by both the
994 parent's and child's original metaclasses.
996 Ultimately, this is all transparent to you except in the case of an
997 unresolvable conflict.
1005 It should be noted that C<super> and C<inner> B<cannot> be used in the same
1006 method. However, they may be combined within the same class hierarchy; see
1007 F<t/014_override_augment_inner_super.t> for an example.
1009 The reason for this is that C<super> is only valid within a method
1010 with the C<override> modifier, and C<inner> will never be valid within an
1011 C<override> method. In fact, C<augment> will skip over any C<override> methods
1012 when searching for its appropriate C<inner>.
1014 This might seem like a restriction, but I am of the opinion that keeping these
1015 two features separate (yet interoperable) actually makes them easy to use, since
1016 their behavior is then easier to predict. Time will tell whether I am right or
1017 not (UPDATE: so far so good).
1023 We offer both a mailing list and a very active IRC channel.
1025 The mailing list is L<moose@perl.org>. You must be subscribed to send
1026 a message. To subscribe, send an empty message to
1027 L<moose-subscribe@perl.org>
1029 You can also visit us at C<#moose> on L<irc://irc.perl.org/#moose>
1030 This channel is quite active, and questions at all levels (on Moose-related
1031 topics ;) are welcome.
1033 =head1 ACKNOWLEDGEMENTS
1037 =item I blame Sam Vilain for introducing me to the insanity that is meta-models.
1039 =item I blame Audrey Tang for then encouraging my meta-model habit in #perl6.
1041 =item Without Yuval "nothingmuch" Kogman this module would not be possible,
1042 and it certainly wouldn't have this name ;P
1044 =item The basis of the TypeContraints module was Rob Kinyon's idea
1045 originally, I just ran with it.
1047 =item Thanks to mst & chansen and the whole #moose posse for all the
1048 early ideas/feature-requests/encouragement/bug-finding.
1050 =item Thanks to David "Theory" Wheeler for meta-discussions and spelling fixes.
1058 =item L<http://www.iinteractive.com/moose>
1060 This is the official web home of Moose, it contains links to our public git repository
1061 as well as links to a number of talks and articles on Moose and Moose related
1064 =item The Moose is flying, a tutorial by Randal Schwartz
1066 Part 1 - L<http://www.stonehenge.com/merlyn/LinuxMag/col94.html>
1068 Part 2 - L<http://www.stonehenge.com/merlyn/LinuxMag/col95.html>
1070 =item Several Moose extension modules in the C<MooseX::> namespace.
1072 See L<http://search.cpan.org/search?query=MooseX::> for extensions.
1074 =item Moose stats on ohloh.net - L<http://www.ohloh.net/projects/moose>
1082 =item The Art of the MetaObject Protocol
1084 I mention this in the L<Class::MOP> docs too, this book was critical in
1085 the development of both modules and is highly recommended.
1093 =item L<http://www.cs.utah.edu/plt/publications/oopsla04-gff.pdf>
1095 This paper (suggested by lbr on #moose) was what lead to the implementation
1096 of the C<super>/C<override> and C<inner>/C<augment> features. If you really
1097 want to understand them, I suggest you read this.
1103 All complex software has bugs lurking in it, and this module is no
1106 Please report any bugs to C<bug-moose@rt.cpan.org>, or through the web
1107 interface at L<http://rt.cpan.org>.
1109 You can also discuss feature requests or possible bugs on the Moose mailing
1110 list (moose@perl.org) or on IRC at L<irc://irc.perl.org/#moose>.
1112 =head1 FEATURE REQUESTS
1114 We are very strict about what features we add to the Moose core, especially
1115 the user-visible features. Instead we have made sure that the underlying
1116 meta-system of Moose is as extensible as possible so that you can add your
1117 own features easily.
1119 That said, occasionally there is a feature needed in the meta-system
1120 to support your planned extension, in which case you should either
1121 email the mailing list (moose@perl.org) or join us on IRC at
1122 L<irc://irc.perl.org/#moose> to discuss. The
1123 L<Moose::Manual::Contributing> has more detail about how and when you
1128 Moose is an open project, there are at this point dozens of people who have
1129 contributed, and can contribute. If you have added anything to the Moose
1130 project you have a commit bit on this file and can add your name to the list.
1134 However 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, and help out maintaining 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>
1155 =head2 OTHER CONTRIBUTORS
1159 Adam (Alias) Kennedy
1161 Anders (Debolaz) Nor Berle
1163 Nathan (kolibrie) Gray
1165 Christian (chansen) Hansen
1167 Eric (ewilhelm) Wilhelm
1169 Guillermo (groditi) Roditi
1171 Jess (castaway) Robinson
1175 Robert (phaylon) Sedlacek
1179 Scott (konobi) McWhirter
1181 Shlomi (rindolf) Fish
1183 Wallace (wreis) Reis
1185 Jonathan (jrockway) Rockway
1187 Piotr (dexter) Roszatycki
1189 Sam (mugwump) Vilain
1193 Dylan Hardison (doc fixes)
1195 ... and many other #moose folks
1197 =head1 COPYRIGHT AND LICENSE
1199 Copyright 2006-2010 by Infinity Interactive, Inc.
1201 L<http://www.iinteractive.com>
1203 This library is free software; you can redistribute it and/or modify
1204 it under the same terms as Perl itself.