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 ($args{no_meta}) {
202 # also check for inherited non moose 'meta' method?
203 my $existing = $meta->get_method('meta');
204 if ($existing && !$existing->isa('Class::MOP::Method::Meta')) {
205 Carp::cluck "Moose is overwriting an existing method named "
206 . "'meta' with its own version, in class $class. If "
207 . "this is actually what you want, you should remove "
208 . "the existing method, otherwise, you should pass "
209 . "the '-no_meta => 1' option to 'use Moose'.";
211 $meta->_add_meta_method;
214 # make sure they inherit from Moose::Object
215 $meta->superclasses($base_class)
216 unless $meta->superclasses();
221 # This may be used in some older MooseX extensions.
223 goto &Moose::Exporter::_get_caller;
226 ## make 'em all immutable
229 inline_constructor => 1,
230 constructor_name => "_new",
231 # these are Class::MOP accessors, so they need inlining
232 inline_accessors => 1
233 ) for grep { $_->is_mutable }
236 Moose::Meta::Attribute
238 Moose::Meta::Instance
240 Moose::Meta::TypeCoercion
241 Moose::Meta::TypeCoercion::Union
244 Moose::Meta::Method::Accessor
245 Moose::Meta::Method::Constructor
246 Moose::Meta::Method::Destructor
247 Moose::Meta::Method::Overridden
248 Moose::Meta::Method::Augmented
251 Moose::Meta::Role::Attribute
252 Moose::Meta::Role::Method
253 Moose::Meta::Role::Method::Required
254 Moose::Meta::Role::Method::Conflicting
256 Moose::Meta::Role::Composite
258 Moose::Meta::Role::Application
259 Moose::Meta::Role::Application::RoleSummation
260 Moose::Meta::Role::Application::ToClass
261 Moose::Meta::Role::Application::ToRole
262 Moose::Meta::Role::Application::ToInstance
265 Moose::Meta::Mixin::AttributeCore->meta->make_immutable(
266 inline_constructor => 0,
267 constructor_name => undef,
278 Moose - A postmodern object system for Perl 5
283 use Moose; # automatically turns on strict and warnings
285 has 'x' => (is => 'rw', isa => 'Int');
286 has 'y' => (is => 'rw', isa => 'Int');
299 has 'z' => (is => 'rw', isa => 'Int');
301 after 'clear' => sub {
308 Moose is an extension of the Perl 5 object system.
310 The main goal of Moose is to make Perl 5 Object Oriented programming
311 easier, more consistent and less tedious. With Moose you can to think
312 more about what you want to do and less about the mechanics of OOP.
314 Additionally, Moose is built on top of L<Class::MOP>, which is a
315 metaclass system for Perl 5. This means that Moose not only makes
316 building normal Perl 5 objects better, but it provides the power of
317 metaclass programming as well.
321 If you're new to Moose, the best place to start is the
322 L<Moose::Manual> docs, followed by the L<Moose::Cookbook>. The intro
323 will show you what Moose is, and how it makes Perl 5 OO better.
325 The cookbook recipes on Moose basics will get you up to speed with
326 many of Moose's features quickly. Once you have an idea of what Moose
327 can do, you can use the API documentation to get more detail on
328 features which interest you.
330 =head2 Moose Extensions
332 The C<MooseX::> namespace is the official place to find Moose extensions.
333 These extensions can be found on the CPAN. The easiest way to find them
334 is to search for them (L<http://search.cpan.org/search?query=MooseX::>),
335 or to examine L<Task::Moose> which aims to keep an up-to-date, easily
336 installable list of Moose extensions.
340 Much of the Moose documentation has been translated into other languages.
346 Japanese docs can be found at
347 L<http://perldoc.perlassociation.org/pod/Moose-Doc-JA/index.html>. The
348 source POD files can be found in GitHub:
349 L<http://github.com/jpa/Moose-Doc-JA>
353 =head1 BUILDING CLASSES WITH MOOSE
355 Moose makes every attempt to provide as much convenience as possible during
356 class construction/definition, but still stay out of your way if you want it
357 to. Here are a few items to note when building classes with Moose.
359 When you C<use Moose>, Moose will set the class's parent class to
360 L<Moose::Object>, I<unless> the class using Moose already has a parent
361 class. In addition, specifying a parent with C<extends> will change the parent
364 Moose will also manage all attributes (including inherited ones) that are
365 defined with C<has>. And (assuming you call C<new>, which is inherited from
366 L<Moose::Object>) this includes properly initializing all instance slots,
367 setting defaults where appropriate, and performing any type constraint checking
370 =head1 PROVIDED METHODS
372 Moose provides a number of methods to all your classes, mostly through the
373 inheritance of L<Moose::Object>. There is however, one exception.
379 This is a method which provides access to the current class's metaclass.
383 =head1 EXPORTED FUNCTIONS
385 Moose will export a number of functions into the class's namespace which
386 may then be used to set up the class. These functions all work directly
387 on the current class.
391 =item B<extends (@superclasses)>
393 This function will set the superclass(es) for the current class.
395 This approach is recommended instead of C<use base>, because C<use base>
396 actually C<push>es onto the class's C<@ISA>, whereas C<extends> will
397 replace it. This is important to ensure that classes which do not have
398 superclasses still properly inherit from L<Moose::Object>.
400 Each superclass can be followed by a hash reference with options. Currently,
401 only L<-version|Class::MOP/Class Loading Options> is recognized:
403 extends 'My::Parent' => { -version => 0.01 },
404 'My::OtherParent' => { -version => 0.03 };
406 An exception will be thrown if the version requirements are not
409 =item B<with (@roles)>
411 This will apply a given set of C<@roles> to the local class.
413 Like with C<extends>, each specified role can be followed by a hash
414 reference with a L<-version|Class::MOP/Class Loading Options> option:
416 with 'My::Role' => { -version => 0.32 },
417 'My::Otherrole' => { -version => 0.23 };
419 The specified version requirements must be satisfied, otherwise an
420 exception will be thrown.
422 If your role takes options or arguments, they can be passed along in the
423 hash reference as well.
425 =item B<has $name|@$names =E<gt> %options>
427 This will install an attribute of a given C<$name> into the current class. If
428 the first parameter is an array reference, it will create an attribute for
429 every C<$name> in the list. The C<%options> are the same as those provided by
430 L<Class::MOP::Attribute>, in addition to the list below which are provided by
431 Moose (L<Moose::Meta::Attribute> to be more specific):
435 =item I<is =E<gt> 'rw'|'ro'>
437 The I<is> option accepts either I<rw> (for read/write) or I<ro> (for read
438 only). These will create either a read/write accessor or a read-only
439 accessor respectively, using the same name as the C<$name> of the attribute.
441 If you need more control over how your accessors are named, you can
442 use the L<reader|Class::MOP::Attribute/reader>,
443 L<writer|Class::MOP::Attribute/writer> and
444 L<accessor|Class::MOP::Attribute/accessor> options inherited from
445 L<Class::MOP::Attribute>, however if you use those, you won't need the
448 =item I<isa =E<gt> $type_name>
450 The I<isa> option uses Moose's type constraint facilities to set up runtime
451 type checking for this attribute. Moose will perform the checks during class
452 construction, and within any accessors. The C<$type_name> argument must be a
453 string. The string may be either a class name or a type defined using
454 Moose's type definition features. (Refer to L<Moose::Util::TypeConstraints>
455 for information on how to define a new type, and how to retrieve type meta-data).
457 =item I<coerce =E<gt> (1|0)>
459 This will attempt to use coercion with the supplied type constraint to change
460 the value passed into any accessors or constructors. You B<must> supply a type
461 constraint, and that type constraint B<must> define a coercion. See
462 L<Moose::Cookbook::Basics::Recipe5> for an example.
464 =item I<does =E<gt> $role_name>
466 This will accept the name of a role which the value stored in this attribute
467 is expected to have consumed.
469 =item I<required =E<gt> (1|0)>
471 This marks the attribute as being required. This means a value must be
472 supplied during class construction, I<or> the attribute must be lazy
473 and have either a default or a builder. Note that c<required> does not
474 say anything about the attribute's value, which can be C<undef>.
476 =item I<weak_ref =E<gt> (1|0)>
478 This will tell the class to store the value of this attribute as a weakened
479 reference. If an attribute is a weakened reference, it B<cannot> also be
482 =item I<lazy =E<gt> (1|0)>
484 This will tell the class to not create this slot until absolutely necessary.
485 If an attribute is marked as lazy it B<must> have a default supplied.
487 =item I<auto_deref =E<gt> (1|0)>
489 This tells the accessor to automatically dereference the value of this
490 attribute when called in list context. The accessor will still return a
491 reference when called in scalar context. If this behavior isn't desirable,
492 L<Moose::Meta::Attribute::Native::Trait::Array/elements> or
493 L<Moose::Meta::Attribute::Native::Trait::Hash/elements> may be a better
494 choice. The I<auto_deref> option is only legal if your I<isa> option is
495 either C<ArrayRef> or C<HashRef>.
497 =item I<trigger =E<gt> $code>
499 The I<trigger> option is a CODE reference which will be called after
500 the value of the attribute is set. The CODE ref is passed the
501 instance itself, the updated value, and the original value if the
502 attribute was already set.
504 You B<can> have a trigger on a read-only attribute.
506 B<NOTE:> Triggers will only fire when you B<assign> to the attribute,
507 either in the constructor, or using the writer. Default and built values will
508 B<not> cause the trigger to be fired.
510 =item I<handles =E<gt> ARRAY | HASH | REGEXP | ROLE | ROLETYPE | DUCKTYPE | CODE>
512 The I<handles> option provides Moose classes with automated delegation features.
513 This is a pretty complex and powerful option. It accepts many different option
514 formats, each with its own benefits and drawbacks.
516 B<NOTE:> The class being delegated to does not need to be a Moose based class,
517 which is why this feature is especially useful when wrapping non-Moose classes.
519 All I<handles> option formats share the following traits:
521 You cannot override a locally defined method with a delegated method; an
522 exception will be thrown if you try. That is to say, if you define C<foo> in
523 your class, you cannot override it with a delegated C<foo>. This is almost never
524 something you would want to do, and if it is, you should do it by hand and not
527 You cannot override any of the methods found in Moose::Object, or the C<BUILD>
528 and C<DEMOLISH> methods. These will not throw an exception, but will silently
529 move on to the next method in the list. My reasoning for this is that you would
530 almost never want to do this, since it usually breaks your class. As with
531 overriding locally defined methods, if you do want to do this, you should do it
532 manually, not with Moose.
534 You do not I<need> to have a reader (or accessor) for the attribute in order
535 to delegate to it. Moose will create a means of accessing the value for you,
536 however this will be several times B<less> efficient then if you had given
537 the attribute a reader (or accessor) to use.
539 Below is the documentation for each option format:
545 This is the most common usage for I<handles>. You basically pass a list of
546 method names to be delegated, and Moose will install a delegation method
551 This is the second most common usage for I<handles>. Instead of a list of
552 method names, you pass a HASH ref where each key is the method name you
553 want installed locally, and its value is the name of the original method
554 in the class being delegated to.
556 This can be very useful for recursive classes like trees. Here is a
557 quick example (soon to be expanded into a Moose::Cookbook recipe):
562 has 'node' => (is => 'rw', isa => 'Any');
567 default => sub { [] }
575 parent_node => 'node',
576 siblings => 'children',
580 In this example, the Tree package gets C<parent_node> and C<siblings> methods,
581 which delegate to the C<node> and C<children> methods (respectively) of the Tree
582 instance stored in the C<parent> slot.
584 You may also use an array reference to curry arguments to the original method.
588 handles => { set_foo => [ set => 'foo' ] },
591 # $self->set_foo(...) calls $self->thing->set('foo', ...)
593 The first element of the array reference is the original method name, and the
594 rest is a list of curried arguments.
598 The regexp option works very similar to the ARRAY option, except that it builds
599 the list of methods for you. It starts by collecting all possible methods of the
600 class being delegated to, then filters that list using the regexp supplied here.
602 B<NOTE:> An I<isa> option is required when using the regexp option format. This
603 is so that we can determine (at compile time) the method list from the class.
604 Without an I<isa> this is just not possible.
606 =item C<ROLE> or C<ROLETYPE>
608 With the role option, you specify the name of a role or a
609 L<role type|Moose::Meta::TypeConstraint::Role> whose "interface" then becomes
610 the list of methods to handle. The "interface" can be defined as; the methods
611 of the role and any required methods of the role. It should be noted that this
612 does B<not> include any method modifiers or generated attribute methods (which
613 is consistent with role composition).
617 With the duck type option, you pass a duck type object whose "interface" then
618 becomes the list of methods to handle. The "interface" can be defined as; the
619 list of methods passed to C<duck_type> to create a duck type object. For more
620 information on C<duck_type> please check
621 L<Moose::Util::TypeConstraints>.
625 This is the option to use when you really want to do something funky. You should
626 only use it if you really know what you are doing, as it involves manual
629 This takes a code reference, which should expect two arguments. The first is the
630 attribute meta-object this I<handles> is attached to. The second is the
631 metaclass of the class being delegated to. It expects you to return a hash (not
632 a HASH ref) of the methods you want mapped.
636 =item I<metaclass =E<gt> $metaclass_name>
638 This tells the class to use a custom attribute metaclass for this particular
639 attribute. Custom attribute metaclasses are useful for extending the
640 capabilities of the I<has> keyword: they are the simplest way to extend the MOP,
641 but they are still a fairly advanced topic and too much to cover here, see
642 L<Moose::Cookbook::Meta::Recipe1> for more information.
644 See L<Metaclass and Trait Name Resolution> for details on how a metaclass name
645 is resolved to a class name.
647 =item I<traits =E<gt> [ @role_names ]>
649 This tells Moose to take the list of C<@role_names> and apply them to the
650 attribute meta-object. This is very similar to the I<metaclass> option, but
651 allows you to use more than one extension at a time.
653 See L<Metaclass and Trait Name Resolution> for details on how a trait name is
654 resolved to a role name.
656 Also see L<Moose::Cookbook::Meta::Recipe3> for a metaclass trait
659 =item I<builder> => Str
661 The value of this key is the name of the method that will be called to
662 obtain the value used to initialize the attribute. See the L<builder
663 option docs in Class::MOP::Attribute|Class::MOP::Attribute/builder>
664 and/or L<Moose::Cookbook::Basics::Recipe8> for more information.
666 =item I<default> => SCALAR | CODE
668 The value of this key is the default value which will initialize the attribute.
670 NOTE: If the value is a simple scalar (string or number), then it can
671 be just passed as is. However, if you wish to initialize it with a
672 HASH or ARRAY ref, then you need to wrap that inside a CODE reference.
673 See the L<default option docs in
674 Class::MOP::Attribute|Class::MOP::Attribute/default> for more
677 =item I<clearer> => Str
679 Creates a method allowing you to clear the value, see the L<clearer option
680 docs in Class::MOP::Attribute|Class::MOP::Attribute/clearer> for more
683 =item I<predicate> => Str
685 Creates a method to perform a basic test to see if a value has been set in the
686 attribute, see the L<predicate option docs in
687 Class::MOP::Attribute|Class::MOP::Attribute/predicate> for more information.
689 =item I<lazy_build> => (0|1)
691 Automatically define lazy => 1 as well as builder => "_build_$attr", clearer =>
692 "clear_$attr', predicate => 'has_$attr' unless they are already defined.
694 =item I<initializer> => Str
696 This may be a method name (referring to a method on the class with
697 this attribute) or a CODE ref. The initializer is used to set the
698 attribute value on an instance when the attribute is set during
699 instance initialization (but not when the value is being assigned
700 to). See the L<initializer option docs in
701 Class::MOP::Attribute|Class::MOP::Attribute/initializer> for more
704 =item I<documentation> => $string
706 An arbitrary string that can be retrieved later by calling C<<
707 $attr->documentation >>.
713 =item B<has +$name =E<gt> %options>
715 This is variation on the normal attribute creator C<has> which allows you to
716 clone and extend an attribute from a superclass or from a role. Here is an
717 example of the superclass usage:
725 default => 'Hello, I am a Foo'
733 has '+message' => (default => 'Hello I am My::Foo');
735 What is happening here is that B<My::Foo> is cloning the C<message> attribute
736 from its parent class B<Foo>, retaining the C<is =E<gt> 'rw'> and C<isa =E<gt>
737 'Str'> characteristics, but changing the value in C<default>.
739 Here is another example, but within the context of a role:
747 default => 'Hello, I am a Foo'
755 has '+message' => (default => 'Hello I am My::Foo');
757 In this case, we are basically taking the attribute which the role supplied
758 and altering it within the bounds of this feature.
760 Note that you can only extend an attribute from either a superclass or a role,
761 you cannot extend an attribute in a role that composes over an attribute from
764 Aside from where the attributes come from (one from superclass, the other
765 from a role), this feature works exactly the same. This feature is restricted
766 somewhat, so as to try and force at least I<some> sanity into it. You are only
767 allowed to change the following attributes:
773 Change the default value of an attribute.
777 Change whether the attribute attempts to coerce a value passed to it.
781 Change if the attribute is required to have a value.
783 =item I<documentation>
785 Change the documentation string associated with the attribute.
789 Change if the attribute lazily initializes the slot.
793 You I<are> allowed to change the type without restriction.
795 It is recommended that you use this freedom with caution. We used to
796 only allow for extension only if the type was a subtype of the parent's
797 type, but we felt that was too restrictive and is better left as a
802 You are allowed to B<add> a new C<handles> definition, but you are B<not>
803 allowed to I<change> one.
807 You are allowed to B<add> a new C<builder> definition, but you are B<not>
808 allowed to I<change> one.
812 You are allowed to B<add> a new C<metaclass> definition, but you are
813 B<not> allowed to I<change> one.
817 You are allowed to B<add> additional traits to the C<traits> definition.
818 These traits will be composed into the attribute, but preexisting traits
819 B<are not> overridden, or removed.
823 =item B<before $name|@names|\@names|qr/.../ =E<gt> sub { ... }>
825 =item B<after $name|@names|\@names|qr/.../ =E<gt> sub { ... }>
827 =item B<around $name|@names|\@names|qr/.../ =E<gt> sub { ... }>
829 These three items are syntactic sugar for the before, after, and around method
830 modifier features that L<Class::MOP> provides. More information on these may be
831 found in L<Moose::Manual::MethodModifiers> and the
832 L<Class::MOP::Class documentation|Class::MOP::Class/"Method Modifiers">.
836 The keyword C<super> is a no-op when called outside of an C<override> method. In
837 the context of an C<override> method, it will call the next most appropriate
838 superclass method with the same arguments as the original method.
840 =item B<override ($name, &sub)>
842 An C<override> method is a way of explicitly saying "I am overriding this
843 method from my superclass". You can call C<super> within this method, and
844 it will work as expected. The same thing I<can> be accomplished with a normal
845 method call and the C<SUPER::> pseudo-package; it is really your choice.
849 The keyword C<inner>, much like C<super>, is a no-op outside of the context of
850 an C<augment> method. You can think of C<inner> as being the inverse of
851 C<super>; the details of how C<inner> and C<augment> work is best described in
852 the L<Moose::Cookbook::Basics::Recipe6>.
854 =item B<augment ($name, &sub)>
856 An C<augment> method, is a way of explicitly saying "I am augmenting this
857 method from my superclass". Once again, the details of how C<inner> and
858 C<augment> work is best described in the L<Moose::Cookbook::Basics::Recipe6>.
862 This is the C<Carp::confess> function, and exported here because I use it
867 This is the C<Scalar::Util::blessed> function, it is exported here because I
868 use it all the time. It is highly recommended that this is used instead of
869 C<ref> anywhere you need to test for an object's class name.
875 When you use Moose, you can specify which metaclass to use:
877 use Moose -metaclass => 'My::Meta::Class';
879 You can also specify traits which will be applied to your metaclass:
881 use Moose -traits => 'My::Trait';
883 This is very similar to the attribute traits feature. When you do
884 this, your class's C<meta> object will have the specified traits
885 applied to it. See L<Metaclass and Trait Name Resolution> for more
888 =head2 Metaclass and Trait Name Resolution
890 By default, when given a trait name, Moose simply tries to load a
891 class of the same name. If such a class does not exist, it then looks
892 for for a class matching
893 B<Moose::Meta::$type::Custom::Trait::$trait_name>. The C<$type>
894 variable here will be one of B<Attribute> or B<Class>, depending on
895 what the trait is being applied to.
897 If a class with this long name exists, Moose checks to see if it has
898 the method C<register_implementation>. This method is expected to
899 return the I<real> class name of the trait. If there is no
900 C<register_implementation> method, it will fall back to using
901 B<Moose::Meta::$type::Custom::Trait::$trait> as the trait name.
903 The lookup method for metaclasses is the same, except that it looks
904 for a class matching B<Moose::Meta::$type::Custom::$metaclass_name>.
906 If all this is confusing, take a look at
907 L<Moose::Cookbook::Meta::Recipe3>, which demonstrates how to create an
910 =head1 UNIMPORTING FUNCTIONS
914 Moose offers a way to remove the keywords it exports, through the C<unimport>
915 method. You simply have to say C<no Moose> at the bottom of your code for this
916 to work. Here is an example:
921 has 'first_name' => (is => 'rw', isa => 'Str');
922 has 'last_name' => (is => 'rw', isa => 'Str');
926 $self->first_name . ' ' . $self->last_name
929 no Moose; # keywords are removed from the Person package
931 =head1 EXTENDING AND EMBEDDING MOOSE
933 To learn more about extending Moose, we recommend checking out the
934 "Extending" recipes in the L<Moose::Cookbook>, starting with
935 L<Moose::Cookbook::Extending::Recipe1>, which provides an overview of
936 all the different ways you might extend Moose.
938 =head2 B<< Moose->init_meta(for_class => $class, base_class => $baseclass, metaclass => $metaclass) >>
940 The C<init_meta> method sets up the metaclass object for the class
941 specified by C<for_class>. This method injects a a C<meta> accessor
942 into the class so you can get at this object. It also sets the class's
943 superclass to C<base_class>, with L<Moose::Object> as the default.
945 C<init_meta> returns the metaclass object for C<$class>.
947 You can specify an alternate metaclass with the C<metaclass> option.
949 For more detail on this topic, see L<Moose::Cookbook::Extending::Recipe2>.
951 This method used to be documented as a function which accepted
952 positional parameters. This calling style will still work for
953 backwards compatibility, but is deprecated.
957 Moose's C<import> method supports the L<Sub::Exporter> form of C<{into =E<gt> $pkg}>
958 and C<{into_level =E<gt> 1}>.
960 B<NOTE>: Doing this is more or less deprecated. Use L<Moose::Exporter>
961 instead, which lets you stack multiple C<Moose.pm>-alike modules
962 sanely. It handles getting the exported functions into the right place
965 =head2 B<throw_error>
967 An alias for C<confess>, used by internally by Moose.
969 =head2 The MooseX:: namespace
971 Generally if you're writing an extension I<for> Moose itself you'll want
972 to put your extension in the C<MooseX::> namespace. This namespace is
973 specifically for extensions that make Moose better or different in some
974 fundamental way. It is traditionally B<not> for a package that just happens
975 to use Moose. This namespace follows from the examples of the C<LWPx::>
976 and C<DBIx::> namespaces that perform the same function for C<LWP> and C<DBI>
979 =head1 METACLASS COMPATIBILITY AND MOOSE
981 Metaclass compatibility is a thorny subject. You should start by
982 reading the "About Metaclass compatibility" section in the
985 Moose will attempt to resolve a few cases of metaclass incompatibility
986 when you set the superclasses for a class, in addition to the cases that
987 C<Class::MOP> handles.
989 Moose tries to determine if the metaclasses only "differ by roles". This
990 means that the parent and child's metaclass share a common ancestor in
991 their respective hierarchies, and that the subclasses under the common
992 ancestor are only different because of role applications. This case is
993 actually fairly common when you mix and match various C<MooseX::*>
994 modules, many of which apply roles to the metaclass.
996 If the parent and child do differ by roles, Moose replaces the
997 metaclass in the child with a newly created metaclass. This metaclass
998 is a subclass of the parent's metaclass, does all of the roles that
999 the child's metaclass did before being replaced. Effectively, this
1000 means the new metaclass does all of the roles done by both the
1001 parent's and child's original metaclasses.
1003 Ultimately, this is all transparent to you except in the case of an
1004 unresolvable conflict.
1012 It should be noted that C<super> and C<inner> B<cannot> be used in the same
1013 method. However, they may be combined within the same class hierarchy; see
1014 F<t/014_override_augment_inner_super.t> for an example.
1016 The reason for this is that C<super> is only valid within a method
1017 with the C<override> modifier, and C<inner> will never be valid within an
1018 C<override> method. In fact, C<augment> will skip over any C<override> methods
1019 when searching for its appropriate C<inner>.
1021 This might seem like a restriction, but I am of the opinion that keeping these
1022 two features separate (yet interoperable) actually makes them easy to use, since
1023 their behavior is then easier to predict. Time will tell whether I am right or
1024 not (UPDATE: so far so good).
1030 We offer both a mailing list and a very active IRC channel.
1032 The mailing list is L<moose@perl.org>. You must be subscribed to send
1033 a message. To subscribe, send an empty message to
1034 L<moose-subscribe@perl.org>
1036 You can also visit us at C<#moose> on L<irc://irc.perl.org/#moose>
1037 This channel is quite active, and questions at all levels (on Moose-related
1038 topics ;) are welcome.
1040 =head1 ACKNOWLEDGEMENTS
1044 =item I blame Sam Vilain for introducing me to the insanity that is meta-models.
1046 =item I blame Audrey Tang for then encouraging my meta-model habit in #perl6.
1048 =item Without Yuval "nothingmuch" Kogman this module would not be possible,
1049 and it certainly wouldn't have this name ;P
1051 =item The basis of the TypeContraints module was Rob Kinyon's idea
1052 originally, I just ran with it.
1054 =item Thanks to mst & chansen and the whole #moose posse for all the
1055 early ideas/feature-requests/encouragement/bug-finding.
1057 =item Thanks to David "Theory" Wheeler for meta-discussions and spelling fixes.
1065 =item L<http://www.iinteractive.com/moose>
1067 This is the official web home of Moose, it contains links to our public git repository
1068 as well as links to a number of talks and articles on Moose and Moose related
1071 =item The Moose is flying, a tutorial by Randal Schwartz
1073 Part 1 - L<http://www.stonehenge.com/merlyn/LinuxMag/col94.html>
1075 Part 2 - L<http://www.stonehenge.com/merlyn/LinuxMag/col95.html>
1077 =item Several Moose extension modules in the C<MooseX::> namespace.
1079 See L<http://search.cpan.org/search?query=MooseX::> for extensions.
1081 =item Moose stats on ohloh.net - L<http://www.ohloh.net/projects/moose>
1089 =item The Art of the MetaObject Protocol
1091 I mention this in the L<Class::MOP> docs too, this book was critical in
1092 the development of both modules and is highly recommended.
1100 =item L<http://www.cs.utah.edu/plt/publications/oopsla04-gff.pdf>
1102 This paper (suggested by lbr on #moose) was what lead to the implementation
1103 of the C<super>/C<override> and C<inner>/C<augment> features. If you really
1104 want to understand them, I suggest you read this.
1110 All complex software has bugs lurking in it, and this module is no
1113 Please report any bugs to C<bug-moose@rt.cpan.org>, or through the web
1114 interface at L<http://rt.cpan.org>.
1116 You can also discuss feature requests or possible bugs on the Moose mailing
1117 list (moose@perl.org) or on IRC at L<irc://irc.perl.org/#moose>.
1119 =head1 FEATURE REQUESTS
1121 We are very strict about what features we add to the Moose core, especially
1122 the user-visible features. Instead we have made sure that the underlying
1123 meta-system of Moose is as extensible as possible so that you can add your
1124 own features easily.
1126 That said, occasionally there is a feature needed in the meta-system
1127 to support your planned extension, in which case you should either
1128 email the mailing list (moose@perl.org) or join us on IRC at
1129 L<irc://irc.perl.org/#moose> to discuss. The
1130 L<Moose::Manual::Contributing> has more detail about how and when you
1135 Moose is an open project, there are at this point dozens of people who have
1136 contributed, and can contribute. If you have added anything to the Moose
1137 project you have a commit bit on this file and can add your name to the list.
1141 However there are only a few people with the rights to release a new version
1142 of Moose. The Moose Cabal are the people to go to with questions regarding
1143 the wider purview of Moose, and help out maintaining not just the code
1144 but the community as well.
1146 Stevan (stevan) Little E<lt>stevan@iinteractive.comE<gt>
1148 Jesse (doy) Luehrs E<lt>doy at tozt dot netE<gt>
1150 Yuval (nothingmuch) Kogman
1152 Shawn (sartak) Moore E<lt>sartak@bestpractical.comE<gt>
1154 Hans Dieter (confound) Pearcey E<lt>hdp@pobox.comE<gt>
1156 Chris (perigrin) Prather
1158 Florian Ragwitz E<lt>rafl@debian.orgE<gt>
1160 Dave (autarch) Rolsky E<lt>autarch@urth.orgE<gt>
1162 =head2 OTHER CONTRIBUTORS
1166 Adam (Alias) Kennedy
1168 Anders (Debolaz) Nor Berle
1170 Nathan (kolibrie) Gray
1172 Christian (chansen) Hansen
1174 Eric (ewilhelm) Wilhelm
1176 Guillermo (groditi) Roditi
1178 Jess (castaway) Robinson
1182 Robert (phaylon) Sedlacek
1186 Scott (konobi) McWhirter
1188 Shlomi (rindolf) Fish
1190 Wallace (wreis) Reis
1192 Jonathan (jrockway) Rockway
1194 Piotr (dexter) Roszatycki
1196 Sam (mugwump) Vilain
1200 Dylan Hardison (doc fixes)
1202 ... and many other #moose folks
1204 =head1 COPYRIGHT AND LICENSE
1206 Copyright 2006-2010 by Infinity Interactive, Inc.
1208 L<http://www.iinteractive.com>
1210 This library is free software; you can redistribute it and/or modify
1211 it under the same terms as Perl itself.