8 $VERSION = eval $VERSION;
9 our $AUTHORITY = 'cpan:STEVAN';
11 use Scalar::Util 'blessed';
18 use Moose::Meta::Class;
19 use Moose::Meta::TypeConstraint;
20 use Moose::Meta::TypeCoercion;
21 use Moose::Meta::Attribute;
22 use Moose::Meta::Instance;
26 use Moose::Meta::Role;
27 use Moose::Meta::Role::Composite;
28 use Moose::Meta::Role::Application;
29 use Moose::Meta::Role::Application::RoleSummation;
30 use Moose::Meta::Role::Application::ToClass;
31 use Moose::Meta::Role::Application::ToRole;
32 use Moose::Meta::Role::Application::ToInstance;
34 use Moose::Util::TypeConstraints;
37 use Moose::Meta::Attribute::Native;
48 Moose->throw_error("Must derive at least one class") unless @_;
50 # this checks the metaclass to make sure
51 # it is correct, sometimes it can get out
52 # of sync when the classes are being built
53 $meta->superclasses(@_);
57 Moose::Util::apply_all_roles(shift, @_);
64 Moose->throw_error('Usage: has \'name\' => ( key => value, ... )')
67 my %options = ( definition_context => Moose::Util::_caller_info(), @_ );
68 my $attrs = ( ref($name) eq 'ARRAY' ) ? $name : [ ($name) ];
69 $meta->add_attribute( $_, %options ) for @$attrs;
73 Moose::Util::add_method_modifier(shift, 'before', \@_);
77 Moose::Util::add_method_modifier(shift, 'after', \@_);
81 Moose::Util::add_method_modifier(shift, 'around', \@_);
89 # This check avoids a recursion loop - see
90 # t/100_bugs/020_super_recursion.t
91 return if defined $SUPER_PACKAGE && $SUPER_PACKAGE ne caller();
92 return unless $SUPER_BODY; $SUPER_BODY->(@SUPER_ARGS);
97 my ( $name, $method ) = @_;
98 $meta->add_override_method_modifier( $name => $method );
103 our ( %INNER_BODY, %INNER_ARGS );
105 if ( my $body = $INNER_BODY{$pkg} ) {
106 my @args = @{ $INNER_ARGS{$pkg} };
107 local $INNER_ARGS{$pkg};
108 local $INNER_BODY{$pkg};
109 return $body->(@args);
117 my ( $name, $method ) = @_;
118 $meta->add_augment_method_modifier( $name => $method );
121 Moose::Exporter->setup_import_methods(
123 qw( extends with has before after around override augment )
128 \&Scalar::Util::blessed,
133 # This used to be called as a function. This hack preserves
134 # backwards compatibility.
135 if ( $_[0] ne __PACKAGE__ ) {
136 return __PACKAGE__->init_meta(
146 my $class = $args{for_class}
147 or Moose->throw_error("Cannot call init_meta without specifying a for_class");
148 my $base_class = $args{base_class} || 'Moose::Object';
149 my $metaclass = $args{metaclass} || 'Moose::Meta::Class';
151 Moose->throw_error("The Metaclass $metaclass must be a subclass of Moose::Meta::Class.")
152 unless $metaclass->isa('Moose::Meta::Class');
154 # make a subtype for each Moose class
156 unless find_type_constraint($class);
160 if ( $meta = Class::MOP::get_metaclass_by_name($class) ) {
161 unless ( $meta->isa("Moose::Meta::Class") ) {
162 my $error_message = "$class already has a metaclass, but it does not inherit $metaclass ($meta).";
163 if ( $meta->isa('Moose::Meta::Role') ) {
164 Moose->throw_error($error_message . ' You cannot make the same thing a role and a class. Remove either Moose or Moose::Role.');
166 Moose->throw_error($error_message);
170 # no metaclass, no 'meta' method
172 # now we check whether our ancestors have metaclass, and if so borrow that
173 my ( undef, @isa ) = @{ $class->mro::get_linear_isa };
175 foreach my $ancestor ( @isa ) {
176 my $ancestor_meta = Class::MOP::get_metaclass_by_name($ancestor) || next;
178 my $ancestor_meta_class = ($ancestor_meta->is_immutable
179 ? $ancestor_meta->_get_mutable_metaclass_name
180 : ref($ancestor_meta));
182 # if we have an ancestor metaclass that inherits $metaclass, we use
183 # that. This is like _fix_metaclass_incompatibility, but we can do it now.
185 # the case of having an ancestry is not very common, but arises in
187 unless ( $metaclass->isa( $ancestor_meta_class ) ) {
188 if ( $ancestor_meta_class->isa($metaclass) ) {
189 $metaclass = $ancestor_meta_class;
194 $meta = $metaclass->initialize($class);
197 if ( $class->can('meta') ) {
198 # check 'meta' method
200 # it may be inherited
203 # this is the case where the metaclass pragma
204 # was used before the 'use Moose' statement to
205 # override a specific class
206 my $method_meta = $class->meta;
208 ( blessed($method_meta) && $method_meta->isa('Moose::Meta::Class') )
209 || Moose->throw_error("$class already has a &meta function, but it does not return a Moose::Meta::Class ($method_meta)");
211 $meta = $method_meta;
214 unless ( $meta->has_method("meta") ) { # don't overwrite
215 # also check for inherited non moose 'meta' method?
216 # FIXME also skip this if the user requested by passing an option
219 # re-initialize so it inherits properly
220 $metaclass->initialize( ref($_[0]) || $_[0] );
225 # make sure they inherit from Moose::Object
226 $meta->superclasses($base_class)
227 unless $meta->superclasses();
232 # This may be used in some older MooseX extensions.
234 goto &Moose::Exporter::_get_caller;
237 ## make 'em all immutable
240 inline_constructor => 1,
241 constructor_name => "_new",
242 # these are Class::MOP accessors, so they need inlining
243 inline_accessors => 1
244 ) for grep { $_->is_mutable }
247 Moose::Meta::Attribute
249 Moose::Meta::Instance
251 Moose::Meta::TypeCoercion
252 Moose::Meta::TypeCoercion::Union
255 Moose::Meta::Method::Accessor
256 Moose::Meta::Method::Constructor
257 Moose::Meta::Method::Destructor
258 Moose::Meta::Method::Overridden
259 Moose::Meta::Method::Augmented
262 Moose::Meta::Role::Attribute
263 Moose::Meta::Role::Method
264 Moose::Meta::Role::Method::Required
265 Moose::Meta::Role::Method::Conflicting
267 Moose::Meta::Role::Composite
269 Moose::Meta::Role::Application
270 Moose::Meta::Role::Application::RoleSummation
271 Moose::Meta::Role::Application::ToClass
272 Moose::Meta::Role::Application::ToRole
273 Moose::Meta::Role::Application::ToInstance
276 Moose::Meta::Mixin::AttributeCore->meta->make_immutable(
277 inline_constructor => 0,
278 constructor_name => undef,
289 Moose - A postmodern object system for Perl 5
294 use Moose; # automatically turns on strict and warnings
296 has 'x' => (is => 'rw', isa => 'Int');
297 has 'y' => (is => 'rw', isa => 'Int');
310 has 'z' => (is => 'rw', isa => 'Int');
312 after 'clear' => sub {
319 Moose is an extension of the Perl 5 object system.
321 The main goal of Moose is to make Perl 5 Object Oriented programming
322 easier, more consistent and less tedious. With Moose you can to think
323 more about what you want to do and less about the mechanics of OOP.
325 Additionally, Moose is built on top of L<Class::MOP>, which is a
326 metaclass system for Perl 5. This means that Moose not only makes
327 building normal Perl 5 objects better, but it provides the power of
328 metaclass programming as well.
332 If you're new to Moose, the best place to start is the
333 L<Moose::Manual> docs, followed by the L<Moose::Cookbook>. The intro
334 will show you what Moose is, and how it makes Perl 5 OO better.
336 The cookbook recipes on Moose basics will get you up to speed with
337 many of Moose's features quickly. Once you have an idea of what Moose
338 can do, you can use the API documentation to get more detail on
339 features which interest you.
341 =head2 Moose Extensions
343 The C<MooseX::> namespace is the official place to find Moose extensions.
344 These extensions can be found on the CPAN. The easiest way to find them
345 is to search for them (L<http://search.cpan.org/search?query=MooseX::>),
346 or to examine L<Task::Moose> which aims to keep an up-to-date, easily
347 installable list of Moose extensions.
351 Much of the Moose documentation has been translated into other languages.
357 Japanese docs can be found at
358 L<http://perldoc.perlassociation.org/pod/Moose-Doc-JA/index.html>. The
359 source POD files can be found in GitHub:
360 L<http://github.com/jpa/Moose-Doc-JA>
364 =head1 BUILDING CLASSES WITH MOOSE
366 Moose makes every attempt to provide as much convenience as possible during
367 class construction/definition, but still stay out of your way if you want it
368 to. Here are a few items to note when building classes with Moose.
370 Unless specified with C<extends>, any class which uses Moose will
371 inherit from L<Moose::Object>.
373 Moose will also manage all attributes (including inherited ones) that are
374 defined with C<has>. And (assuming you call C<new>, which is inherited from
375 L<Moose::Object>) this includes properly initializing all instance slots,
376 setting defaults where appropriate, and performing any type constraint checking
379 =head1 PROVIDED METHODS
381 Moose provides a number of methods to all your classes, mostly through the
382 inheritance of L<Moose::Object>. There is however, one exception.
388 This is a method which provides access to the current class's metaclass.
392 =head1 EXPORTED FUNCTIONS
394 Moose will export a number of functions into the class's namespace which
395 may then be used to set up the class. These functions all work directly
396 on the current class.
400 =item B<extends (@superclasses)>
402 This function will set the superclass(es) for the current class.
404 This approach is recommended instead of C<use base>, because C<use base>
405 actually C<push>es onto the class's C<@ISA>, whereas C<extends> will
406 replace it. This is important to ensure that classes which do not have
407 superclasses still properly inherit from L<Moose::Object>.
409 Each superclass can be followed by a hash reference with options. Currently,
410 only L<-version|Class::MOP/Class Loading Options> is recognized:
412 extends 'My::Parent' => { -version => 0.01 },
413 'My::OtherParent' => { -version => 0.03 };
415 An exception will be thrown if the version requirements are not
418 =item B<with (@roles)>
420 This will apply a given set of C<@roles> to the local class.
422 Like with C<extends>, each specified role can be followed by a hash
423 reference with a L<-version|Class::MOP/Class Loading Options> option:
425 with 'My::Role' => { -version => 0.32 },
426 'My::Otherrole' => { -version => 0.23 };
428 The specified version requirements must be satisfied, otherwise an
429 exception will be thrown.
431 If your role takes options or arguments, they can be passed along in the
432 hash reference as well.
434 =item B<has $name|@$names =E<gt> %options>
436 This will install an attribute of a given C<$name> into the current class. If
437 the first parameter is an array reference, it will create an attribute for
438 every C<$name> in the list. The C<%options> are the same as those provided by
439 L<Class::MOP::Attribute>, in addition to the list below which are provided by
440 Moose (L<Moose::Meta::Attribute> to be more specific):
444 =item I<is =E<gt> 'rw'|'ro'>
446 The I<is> option accepts either I<rw> (for read/write) or I<ro> (for read
447 only). These will create either a read/write accessor or a read-only
448 accessor respectively, using the same name as the C<$name> of the attribute.
450 If you need more control over how your accessors are named, you can
451 use the L<reader|Class::MOP::Attribute/reader>,
452 L<writer|Class::MOP::Attribute/writer> and
453 L<accessor|Class::MOP::Attribute/accessor> options inherited from
454 L<Class::MOP::Attribute>, however if you use those, you won't need the
457 =item I<isa =E<gt> $type_name>
459 The I<isa> option uses Moose's type constraint facilities to set up runtime
460 type checking for this attribute. Moose will perform the checks during class
461 construction, and within any accessors. The C<$type_name> argument must be a
462 string. The string may be either a class name or a type defined using
463 Moose's type definition features. (Refer to L<Moose::Util::TypeConstraints>
464 for information on how to define a new type, and how to retrieve type meta-data).
466 =item I<coerce =E<gt> (1|0)>
468 This will attempt to use coercion with the supplied type constraint to change
469 the value passed into any accessors or constructors. You B<must> have supplied
470 a type constraint in order for this to work. See L<Moose::Cookbook::Basics::Recipe5>
473 =item I<does =E<gt> $role_name>
475 This will accept the name of a role which the value stored in this attribute
476 is expected to have consumed.
478 =item I<required =E<gt> (1|0)>
480 This marks the attribute as being required. This means a value must be
481 supplied during class construction, I<or> the attribute must be lazy
482 and have either a default or a builder. Note that c<required> does not
483 say anything about the attribute's value, which can be C<undef>.
485 =item I<weak_ref =E<gt> (1|0)>
487 This will tell the class to store the value of this attribute as a weakened
488 reference. If an attribute is a weakened reference, it B<cannot> also be
491 =item I<lazy =E<gt> (1|0)>
493 This will tell the class to not create this slot until absolutely necessary.
494 If an attribute is marked as lazy it B<must> have a default supplied.
496 =item I<auto_deref =E<gt> (1|0)>
498 This tells the accessor to automatically dereference the value of this
499 attribute when called in list context. The accessor will still return a
500 reference when called in scalar context. If this behavior isn't desirable,
501 L<Moose::Meta::Attribute::Native::Trait::Array/elements> or
502 L<Moose::Meta::Attribute::Native::Trait::Hash/elements> may be a better
503 choice. The I<auto_deref> option is only legal if your I<isa> option is
504 either C<ArrayRef> or C<HashRef>.
506 =item I<trigger =E<gt> $code>
508 The I<trigger> option is a CODE reference which will be called after
509 the value of the attribute is set. The CODE ref is passed the
510 instance itself, the updated value, and the original value if the
511 attribute was already set.
513 You B<can> have a trigger on a read-only attribute.
515 B<NOTE:> Triggers will only fire when you B<assign> to the attribute,
516 either in the constructor, or using the writer. Default and built values will
517 B<not> cause the trigger to be fired.
519 =item I<handles =E<gt> ARRAY | HASH | REGEXP | ROLE | ROLETYPE | DUCKTYPE | CODE>
521 The I<handles> option provides Moose classes with automated delegation features.
522 This is a pretty complex and powerful option. It accepts many different option
523 formats, each with its own benefits and drawbacks.
525 B<NOTE:> The class being delegated to does not need to be a Moose based class,
526 which is why this feature is especially useful when wrapping non-Moose classes.
528 All I<handles> option formats share the following traits:
530 You cannot override a locally defined method with a delegated method; an
531 exception will be thrown if you try. That is to say, if you define C<foo> in
532 your class, you cannot override it with a delegated C<foo>. This is almost never
533 something you would want to do, and if it is, you should do it by hand and not
536 You cannot override any of the methods found in Moose::Object, or the C<BUILD>
537 and C<DEMOLISH> methods. These will not throw an exception, but will silently
538 move on to the next method in the list. My reasoning for this is that you would
539 almost never want to do this, since it usually breaks your class. As with
540 overriding locally defined methods, if you do want to do this, you should do it
541 manually, not with Moose.
543 You do not I<need> to have a reader (or accessor) for the attribute in order
544 to delegate to it. Moose will create a means of accessing the value for you,
545 however this will be several times B<less> efficient then if you had given
546 the attribute a reader (or accessor) to use.
548 Below is the documentation for each option format:
554 This is the most common usage for I<handles>. You basically pass a list of
555 method names to be delegated, and Moose will install a delegation method
560 This is the second most common usage for I<handles>. Instead of a list of
561 method names, you pass a HASH ref where each key is the method name you
562 want installed locally, and its value is the name of the original method
563 in the class being delegated to.
565 This can be very useful for recursive classes like trees. Here is a
566 quick example (soon to be expanded into a Moose::Cookbook recipe):
571 has 'node' => (is => 'rw', isa => 'Any');
576 default => sub { [] }
584 parent_node => 'node',
585 siblings => 'children',
589 In this example, the Tree package gets C<parent_node> and C<siblings> methods,
590 which delegate to the C<node> and C<children> methods (respectively) of the Tree
591 instance stored in the C<parent> slot.
593 You may also use an array reference to curry arguments to the original method.
597 handles => { set_foo => [ set => 'foo' ] },
600 # $self->set_foo(...) calls $self->thing->set('foo', ...)
602 The first element of the array reference is the original method name, and the
603 rest is a list of curried arguments.
607 The regexp option works very similar to the ARRAY option, except that it builds
608 the list of methods for you. It starts by collecting all possible methods of the
609 class being delegated to, then filters that list using the regexp supplied here.
611 B<NOTE:> An I<isa> option is required when using the regexp option format. This
612 is so that we can determine (at compile time) the method list from the class.
613 Without an I<isa> this is just not possible.
615 =item C<ROLE> or C<ROLETYPE>
617 With the role option, you specify the name of a role or a
618 L<role type|Moose::Meta::TypeConstraint::Role> whose "interface" then becomes
619 the list of methods to handle. The "interface" can be defined as; the methods
620 of the role and any required methods of the role. It should be noted that this
621 does B<not> include any method modifiers or generated attribute methods (which
622 is consistent with role composition).
626 With the duck type option, you pass a duck type object whose "interface" then
627 becomes the list of methods to handle. The "interface" can be defined as; the
628 list of methods passed to C<duck_type> to create a duck type object. For more
629 information on C<duck_type> please check
630 L<Moose::Util::TypeConstraints>.
634 This is the option to use when you really want to do something funky. You should
635 only use it if you really know what you are doing, as it involves manual
638 This takes a code reference, which should expect two arguments. The first is the
639 attribute meta-object this I<handles> is attached to. The second is the
640 metaclass of the class being delegated to. It expects you to return a hash (not
641 a HASH ref) of the methods you want mapped.
645 =item I<metaclass =E<gt> $metaclass_name>
647 This tells the class to use a custom attribute metaclass for this particular
648 attribute. Custom attribute metaclasses are useful for extending the
649 capabilities of the I<has> keyword: they are the simplest way to extend the MOP,
650 but they are still a fairly advanced topic and too much to cover here, see
651 L<Moose::Cookbook::Meta::Recipe1> for more information.
653 See L<Metaclass and Trait Name Resolution> for details on how a metaclass name
654 is resolved to a class name.
656 =item I<traits =E<gt> [ @role_names ]>
658 This tells Moose to take the list of C<@role_names> and apply them to the
659 attribute meta-object. This is very similar to the I<metaclass> option, but
660 allows you to use more than one extension at a time.
662 See L<Metaclass and Trait Name Resolution> for details on how a trait name is
663 resolved to a role name.
665 Also see L<Moose::Cookbook::Meta::Recipe3> for a metaclass trait
668 =item I<builder> => Str
670 The value of this key is the name of the method that will be called to
671 obtain the value used to initialize the attribute. See the L<builder
672 option docs in Class::MOP::Attribute|Class::MOP::Attribute/builder>
673 and/or L<Moose::Cookbook::Basics::Recipe8> for more information.
675 =item I<default> => SCALAR | CODE
677 The value of this key is the default value which will initialize the attribute.
679 NOTE: If the value is a simple scalar (string or number), then it can
680 be just passed as is. However, if you wish to initialize it with a
681 HASH or ARRAY ref, then you need to wrap that inside a CODE reference.
682 See the L<default option docs in
683 Class::MOP::Attribute|Class::MOP::Attribute/default> for more
686 =item I<clearer> => Str
688 Creates a method allowing you to clear the value, see the L<clearer option
689 docs in Class::MOP::Attribute|Class::MOP::Attribute/clearer> for more
692 =item I<predicate> => Str
694 Creates a method to perform a basic test to see if a value has been set in the
695 attribute, see the L<predicate option docs in
696 Class::MOP::Attribute|Class::MOP::Attribute/predicate> for more information.
698 =item I<lazy_build> => (0|1)
700 Automatically define lazy => 1 as well as builder => "_build_$attr", clearer =>
701 "clear_$attr', predicate => 'has_$attr' unless they are already defined.
703 =item I<initializer> => Str
705 This may be a method name (referring to a method on the class with
706 this attribute) or a CODE ref. The initializer is used to set the
707 attribute value on an instance when the attribute is set during
708 instance initialization (but not when the value is being assigned
709 to). See the L<initializer option docs in
710 Class::MOP::Attribute|Class::MOP::Attribute/initializer> for more
713 =item I<documentation> => $string
715 An arbitrary string that can be retrieved later by calling C<<
716 $attr->documentation >>.
722 =item B<has +$name =E<gt> %options>
724 This is variation on the normal attribute creator C<has> which allows you to
725 clone and extend an attribute from a superclass or from a role. Here is an
726 example of the superclass usage:
734 default => 'Hello, I am a Foo'
742 has '+message' => (default => 'Hello I am My::Foo');
744 What is happening here is that B<My::Foo> is cloning the C<message> attribute
745 from its parent class B<Foo>, retaining the C<is =E<gt> 'rw'> and C<isa =E<gt>
746 'Str'> characteristics, but changing the value in C<default>.
748 Here is another example, but within the context of a role:
756 default => 'Hello, I am a Foo'
764 has '+message' => (default => 'Hello I am My::Foo');
766 In this case, we are basically taking the attribute which the role supplied
767 and altering it within the bounds of this feature.
769 Note that you can only extend an attribute from either a superclass or a role,
770 you cannot extend an attribute in a role that composes over an attribute from
773 Aside from where the attributes come from (one from superclass, the other
774 from a role), this feature works exactly the same. This feature is restricted
775 somewhat, so as to try and force at least I<some> sanity into it. You are only
776 allowed to change the following attributes:
782 Change the default value of an attribute.
786 Change whether the attribute attempts to coerce a value passed to it.
790 Change if the attribute is required to have a value.
792 =item I<documentation>
794 Change the documentation string associated with the attribute.
798 Change if the attribute lazily initializes the slot.
802 You I<are> allowed to change the type without restriction.
804 It is recommended that you use this freedom with caution. We used to
805 only allow for extension only if the type was a subtype of the parent's
806 type, but we felt that was too restrictive and is better left as a
811 You are allowed to B<add> a new C<handles> definition, but you are B<not>
812 allowed to I<change> one.
816 You are allowed to B<add> a new C<builder> definition, but you are B<not>
817 allowed to I<change> one.
821 You are allowed to B<add> a new C<metaclass> definition, but you are
822 B<not> allowed to I<change> one.
826 You are allowed to B<add> additional traits to the C<traits> definition.
827 These traits will be composed into the attribute, but preexisting traits
828 B<are not> overridden, or removed.
832 =item B<before $name|@names|\@names|qr/.../ =E<gt> sub { ... }>
834 =item B<after $name|@names|\@names|qr/.../ =E<gt> sub { ... }>
836 =item B<around $name|@names|\@names|qr/.../ =E<gt> sub { ... }>
838 These three items are syntactic sugar for the before, after, and around method
839 modifier features that L<Class::MOP> provides. More information on these may be
840 found in L<Moose::Manual::MethodModifiers> and the
841 L<Class::MOP::Class documentation|Class::MOP::Class/"Method Modifiers">.
845 The keyword C<super> is a no-op when called outside of an C<override> method. In
846 the context of an C<override> method, it will call the next most appropriate
847 superclass method with the same arguments as the original method.
849 =item B<override ($name, &sub)>
851 An C<override> method is a way of explicitly saying "I am overriding this
852 method from my superclass". You can call C<super> within this method, and
853 it will work as expected. The same thing I<can> be accomplished with a normal
854 method call and the C<SUPER::> pseudo-package; it is really your choice.
858 The keyword C<inner>, much like C<super>, is a no-op outside of the context of
859 an C<augment> method. You can think of C<inner> as being the inverse of
860 C<super>; the details of how C<inner> and C<augment> work is best described in
861 the L<Moose::Cookbook::Basics::Recipe6>.
863 =item B<augment ($name, &sub)>
865 An C<augment> method, is a way of explicitly saying "I am augmenting this
866 method from my superclass". Once again, the details of how C<inner> and
867 C<augment> work is best described in the L<Moose::Cookbook::Basics::Recipe6>.
871 This is the C<Carp::confess> function, and exported here because I use it
876 This is the C<Scalar::Util::blessed> function, it is exported here because I
877 use it all the time. It is highly recommended that this is used instead of
878 C<ref> anywhere you need to test for an object's class name.
884 When you use Moose, you can specify which metaclass to use:
886 use Moose -metaclass => 'My::Meta::Class';
888 You can also specify traits which will be applied to your metaclass:
890 use Moose -traits => 'My::Trait';
892 This is very similar to the attribute traits feature. When you do
893 this, your class's C<meta> object will have the specified traits
894 applied to it. See L<Metaclass and Trait Name Resolution> for more
897 =head2 Metaclass and Trait Name Resolution
899 By default, when given a trait name, Moose simply tries to load a
900 class of the same name. If such a class does not exist, it then looks
901 for for a class matching
902 B<Moose::Meta::$type::Custom::Trait::$trait_name>. The C<$type>
903 variable here will be one of B<Attribute> or B<Class>, depending on
904 what the trait is being applied to.
906 If a class with this long name exists, Moose checks to see if it has
907 the method C<register_implementation>. This method is expected to
908 return the I<real> class name of the trait. If there is no
909 C<register_implementation> method, it will fall back to using
910 B<Moose::Meta::$type::Custom::Trait::$trait> as the trait name.
912 The lookup method for metaclasses is the same, except that it looks
913 for a class matching B<Moose::Meta::$type::Custom::$metaclass_name>.
915 If all this is confusing, take a look at
916 L<Moose::Cookbook::Meta::Recipe3>, which demonstrates how to create an
919 =head1 UNIMPORTING FUNCTIONS
923 Moose offers a way to remove the keywords it exports, through the C<unimport>
924 method. You simply have to say C<no Moose> at the bottom of your code for this
925 to work. Here is an example:
930 has 'first_name' => (is => 'rw', isa => 'Str');
931 has 'last_name' => (is => 'rw', isa => 'Str');
935 $self->first_name . ' ' . $self->last_name
938 no Moose; # keywords are removed from the Person package
940 =head1 EXTENDING AND EMBEDDING MOOSE
942 To learn more about extending Moose, we recommend checking out the
943 "Extending" recipes in the L<Moose::Cookbook>, starting with
944 L<Moose::Cookbook::Extending::Recipe1>, which provides an overview of
945 all the different ways you might extend Moose.
947 =head2 B<< Moose->init_meta(for_class => $class, base_class => $baseclass, metaclass => $metaclass) >>
949 The C<init_meta> method sets up the metaclass object for the class
950 specified by C<for_class>. This method injects a a C<meta> accessor
951 into the class so you can get at this object. It also sets the class's
952 superclass to C<base_class>, with L<Moose::Object> as the default.
954 C<init_meta> returns the metaclass object for C<$class>.
956 You can specify an alternate metaclass with the C<metaclass> option.
958 For more detail on this topic, see L<Moose::Cookbook::Extending::Recipe2>.
960 This method used to be documented as a function which accepted
961 positional parameters. This calling style will still work for
962 backwards compatibility, but is deprecated.
966 Moose's C<import> method supports the L<Sub::Exporter> form of C<{into =E<gt> $pkg}>
967 and C<{into_level =E<gt> 1}>.
969 B<NOTE>: Doing this is more or less deprecated. Use L<Moose::Exporter>
970 instead, which lets you stack multiple C<Moose.pm>-alike modules
971 sanely. It handles getting the exported functions into the right place
974 =head2 B<throw_error>
976 An alias for C<confess>, used by internally by Moose.
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, 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.
1005 =head2 The MooseX:: namespace
1007 Generally if you're writing an extension I<for> Moose itself you'll want
1008 to put your extension in the C<MooseX::> namespace. This namespace is
1009 specifically for extensions that make Moose better or different in some
1010 fundamental way. It is traditionally B<not> for a package that just happens
1011 to use Moose. This namespace follows from the examples of the C<LWPx::>
1012 and C<DBIx::> namespaces that perform the same function for C<LWP> and C<DBI>
1021 It should be noted that C<super> and C<inner> B<cannot> be used in the same
1022 method. However, they may be combined within the same class hierarchy; see
1023 F<t/014_override_augment_inner_super.t> for an example.
1025 The reason for this is that C<super> is only valid within a method
1026 with the C<override> modifier, and C<inner> will never be valid within an
1027 C<override> method. In fact, C<augment> will skip over any C<override> methods
1028 when searching for its appropriate C<inner>.
1030 This might seem like a restriction, but I am of the opinion that keeping these
1031 two features separate (yet interoperable) actually makes them easy to use, since
1032 their behavior is then easier to predict. Time will tell whether I am right or
1033 not (UPDATE: so far so good).
1039 We offer both a mailing list and a very active IRC channel.
1041 The mailing list is L<moose@perl.org>. You must be subscribed to send
1042 a message. To subscribe, send an empty message to
1043 L<moose-subscribe@perl.org>
1045 You can also visit us at C<#moose> on L<irc://irc.perl.org/#moose>
1046 This channel is quite active, and questions at all levels (on Moose-related
1047 topics ;) are welcome.
1049 =head1 ACKNOWLEDGEMENTS
1053 =item I blame Sam Vilain for introducing me to the insanity that is meta-models.
1055 =item I blame Audrey Tang for then encouraging my meta-model habit in #perl6.
1057 =item Without Yuval "nothingmuch" Kogman this module would not be possible,
1058 and it certainly wouldn't have this name ;P
1060 =item The basis of the TypeContraints module was Rob Kinyon's idea
1061 originally, I just ran with it.
1063 =item Thanks to mst & chansen and the whole #moose posse for all the
1064 early ideas/feature-requests/encouragement/bug-finding.
1066 =item Thanks to David "Theory" Wheeler for meta-discussions and spelling fixes.
1074 =item L<http://www.iinteractive.com/moose>
1076 This is the official web home of Moose, it contains links to our public git repository
1077 as well as links to a number of talks and articles on Moose and Moose related
1080 =item The Moose is flying, a tutorial by Randal Schwartz
1082 Part 1 - L<http://www.stonehenge.com/merlyn/LinuxMag/col94.html>
1084 Part 2 - L<http://www.stonehenge.com/merlyn/LinuxMag/col95.html>
1086 =item Several Moose extension modules in the C<MooseX::> namespace.
1088 See L<http://search.cpan.org/search?query=MooseX::> for extensions.
1090 =item Moose stats on ohloh.net - L<http://www.ohloh.net/projects/moose>
1098 =item The Art of the MetaObject Protocol
1100 I mention this in the L<Class::MOP> docs too, this book was critical in
1101 the development of both modules and is highly recommended.
1109 =item L<http://www.cs.utah.edu/plt/publications/oopsla04-gff.pdf>
1111 This paper (suggested by lbr on #moose) was what lead to the implementation
1112 of the C<super>/C<override> and C<inner>/C<augment> features. If you really
1113 want to understand them, I suggest you read this.
1119 All complex software has bugs lurking in it, and this module is no
1122 Please report any bugs to C<bug-moose@rt.cpan.org>, or through the web
1123 interface at L<http://rt.cpan.org>.
1125 You can also discuss feature requests or possible bugs on the Moose mailing
1126 list (moose@perl.org) or on IRC at L<irc://irc.perl.org/#moose>.
1128 =head1 FEATURE REQUESTS
1130 We are very strict about what features we add to the Moose core, especially
1131 the user-visible features. Instead we have made sure that the underlying
1132 meta-system of Moose is as extensible as possible so that you can add your
1133 own features easily.
1135 That said, occasionally there is a feature needed in the meta-system
1136 to support your planned extension, in which case you should either
1137 email the mailing list (moose@perl.org) or join us on IRC at
1138 L<irc://irc.perl.org/#moose> to discuss. The
1139 L<Moose::Manual::Contributing> has more detail about how and when you
1144 Moose is an open project, there are at this point dozens of people who have
1145 contributed, and can contribute. If you have added anything to the Moose
1146 project you have a commit bit on this file and can add your name to the list.
1150 However there are only a few people with the rights to release a new version
1151 of Moose. The Moose Cabal are the people to go to with questions regarding
1152 the wider purview of Moose, and help out maintaining not just the code
1153 but the community as well.
1155 Stevan (stevan) Little E<lt>stevan@iinteractive.comE<gt>
1157 Jesse (doy) Luehrs E<lt>doy at tozt dot netE<gt>
1159 Yuval (nothingmuch) Kogman
1161 Shawn (sartak) Moore E<lt>sartak@bestpractical.comE<gt>
1163 Hans Dieter (confound) Pearcey E<lt>hdp@pobox.comE<gt>
1165 Chris (perigrin) Prather
1167 Florian Ragwitz E<lt>rafl@debian.orgE<gt>
1169 Dave (autarch) Rolsky E<lt>autarch@urth.orgE<gt>
1171 =head2 OTHER CONTRIBUTORS
1175 Adam (Alias) Kennedy
1177 Anders (Debolaz) Nor Berle
1179 Nathan (kolibrie) Gray
1181 Christian (chansen) Hansen
1183 Eric (ewilhelm) Wilhelm
1185 Guillermo (groditi) Roditi
1187 Jess (castaway) Robinson
1191 Robert (phaylon) Sedlacek
1195 Scott (konobi) McWhirter
1197 Shlomi (rindolf) Fish
1199 Wallace (wreis) Reis
1201 Jonathan (jrockway) Rockway
1203 Piotr (dexter) Roszatycki
1205 Sam (mugwump) Vilain
1209 Dylan Hardison (doc fixes)
1211 ... and many other #moose folks
1213 =head1 COPYRIGHT AND LICENSE
1215 Copyright 2006-2010 by Infinity Interactive, Inc.
1217 L<http://www.iinteractive.com>
1219 This library is free software; you can redistribute it and/or modify
1220 it under the same terms as Perl itself.