7 use Scalar::Util 'blessed';
10 use Moose::Deprecated;
16 die "Class::MOP version $Moose::VERSION required--this is version $Class::MOP::VERSION"
17 if $Moose::VERSION && $Class::MOP::VERSION ne $Moose::VERSION;
20 use Moose::Meta::Class;
21 use Moose::Meta::TypeConstraint;
22 use Moose::Meta::TypeCoercion;
23 use Moose::Meta::Attribute;
24 use Moose::Meta::Instance;
28 use Moose::Meta::Role;
29 use Moose::Meta::Role::Composite;
30 use Moose::Meta::Role::Application;
31 use Moose::Meta::Role::Application::RoleSummation;
32 use Moose::Meta::Role::Application::ToClass;
33 use Moose::Meta::Role::Application::ToRole;
34 use Moose::Meta::Role::Application::ToInstance;
36 use Moose::Util::TypeConstraints;
39 use Moose::Meta::Attribute::Native;
50 Moose->throw_error("Must derive at least one class") unless @_;
52 # this checks the metaclass to make sure
53 # it is correct, sometimes it can get out
54 # of sync when the classes are being built
55 $meta->superclasses(@_);
59 Moose::Util::apply_all_roles(shift, @_);
66 Moose->throw_error('Usage: has \'name\' => ( key => value, ... )')
69 my %options = ( definition_context => Moose::Util::_caller_info(), @_ );
70 my $attrs = ( ref($name) eq 'ARRAY' ) ? $name : [ ($name) ];
71 $meta->add_attribute( $_, %options ) for @$attrs;
75 Moose::Util::add_method_modifier(shift, 'before', \@_);
79 Moose::Util::add_method_modifier(shift, 'after', \@_);
83 Moose::Util::add_method_modifier(shift, 'around', \@_);
91 # This check avoids a recursion loop - see
92 # t/bugs/super_recursion.t
93 return if defined $SUPER_PACKAGE && $SUPER_PACKAGE ne caller();
94 return unless $SUPER_BODY; $SUPER_BODY->(@SUPER_ARGS);
99 my ( $name, $method ) = @_;
100 $meta->add_override_method_modifier( $name => $method );
105 our ( %INNER_BODY, %INNER_ARGS );
107 if ( my $body = $INNER_BODY{$pkg} ) {
108 my @args = @{ $INNER_ARGS{$pkg} };
109 local $INNER_ARGS{$pkg};
110 local $INNER_BODY{$pkg};
111 return $body->(@args);
119 my ( $name, $method ) = @_;
120 $meta->add_augment_method_modifier( $name => $method );
123 Moose::Exporter->setup_import_methods(
125 qw( extends with has before after around override augment )
130 \&Scalar::Util::blessed,
135 # This used to be called as a function. This hack preserves
136 # backwards compatibility.
137 if ( $_[0] ne __PACKAGE__ ) {
138 Moose::Deprecated::deprecated(
139 feature => 'Moose::init_meta',
140 message => 'Calling Moose::init_meta as a function is deprecated.'
141 . ' Doing so will throw an error in Moose 2.0200.'
144 return __PACKAGE__->init_meta(
154 my $class = $args{for_class}
155 or Moose->throw_error("Cannot call init_meta without specifying a for_class");
156 my $base_class = $args{base_class} || 'Moose::Object';
157 my $metaclass = $args{metaclass} || 'Moose::Meta::Class';
158 my $meta_name = exists $args{meta_name} ? $args{meta_name} : 'meta';
160 Moose->throw_error("The Metaclass $metaclass must be a subclass of Moose::Meta::Class.")
161 unless $metaclass->isa('Moose::Meta::Class');
163 # make a subtype for each Moose class
165 unless find_type_constraint($class);
169 if ( $meta = Class::MOP::get_metaclass_by_name($class) ) {
170 unless ( $meta->isa("Moose::Meta::Class") ) {
171 my $error_message = "$class already has a metaclass, but it does not inherit $metaclass ($meta).";
172 if ( $meta->isa('Moose::Meta::Role') ) {
173 Moose->throw_error($error_message . ' You cannot make the same thing a role and a class. Remove either Moose or Moose::Role.');
175 Moose->throw_error($error_message);
181 # now we check whether our ancestors have metaclass, and if so borrow that
182 my ( undef, @isa ) = @{ mro::get_linear_isa($class) };
184 foreach my $ancestor ( @isa ) {
185 my $ancestor_meta = Class::MOP::get_metaclass_by_name($ancestor) || next;
187 my $ancestor_meta_class = $ancestor_meta->_real_ref_name;
189 # if we have an ancestor metaclass that inherits $metaclass, we use
190 # that. This is like _fix_metaclass_incompatibility, but we can do it now.
192 # the case of having an ancestry is not very common, but arises in
194 unless ( $metaclass->isa( $ancestor_meta_class ) ) {
195 if ( $ancestor_meta_class->isa($metaclass) ) {
196 $metaclass = $ancestor_meta_class;
201 $meta = $metaclass->initialize($class);
204 if (defined $meta_name) {
205 # also check for inherited non moose 'meta' method?
206 my $existing = $meta->get_method($meta_name);
207 if ($existing && !$existing->isa('Class::MOP::Method::Meta')) {
208 Carp::cluck "Moose is overwriting an existing method named "
209 . "$meta_name in class $class with a method "
210 . "which returns the class's metaclass. If this is "
211 . "actually what you want, you should remove the "
212 . "existing method, otherwise, you should rename or "
213 . "disable this generated method using the "
214 . "'-meta_name' option to 'use Moose'.";
216 $meta->_add_meta_method($meta_name);
219 # make sure they inherit from Moose::Object
220 $meta->superclasses($base_class)
221 unless $meta->superclasses();
226 # This may be used in some older MooseX extensions.
228 goto &Moose::Exporter::_get_caller;
231 ## make 'em all immutable
234 inline_constructor => 1,
235 constructor_name => "_new",
236 # these are Class::MOP accessors, so they need inlining
237 inline_accessors => 1
238 ) for grep { $_->is_mutable }
241 Moose::Meta::Attribute
243 Moose::Meta::Instance
245 Moose::Meta::TypeCoercion
246 Moose::Meta::TypeCoercion::Union
249 Moose::Meta::Method::Accessor
250 Moose::Meta::Method::Constructor
251 Moose::Meta::Method::Destructor
252 Moose::Meta::Method::Overridden
253 Moose::Meta::Method::Augmented
256 Moose::Meta::Role::Attribute
257 Moose::Meta::Role::Method
258 Moose::Meta::Role::Method::Required
259 Moose::Meta::Role::Method::Conflicting
261 Moose::Meta::Role::Composite
263 Moose::Meta::Role::Application
264 Moose::Meta::Role::Application::RoleSummation
265 Moose::Meta::Role::Application::ToClass
266 Moose::Meta::Role::Application::ToRole
267 Moose::Meta::Role::Application::ToInstance
270 Moose::Meta::Mixin::AttributeCore->meta->make_immutable(
271 inline_constructor => 0,
272 constructor_name => undef,
277 # ABSTRACT: A postmodern object system for Perl 5
286 use Moose; # automatically turns on strict and warnings
288 has 'x' => (is => 'rw', isa => 'Int');
289 has 'y' => (is => 'rw', isa => 'Int');
302 has 'z' => (is => 'rw', isa => 'Int');
304 after 'clear' => sub {
311 Moose is an extension of the Perl 5 object system.
313 The main goal of Moose is to make Perl 5 Object Oriented programming
314 easier, more consistent, and less tedious. With Moose you can think
315 more about what you want to do and less about the mechanics of OOP.
317 Additionally, Moose is built on top of L<Class::MOP>, which is a
318 metaclass system for Perl 5. This means that Moose not only makes
319 building normal Perl 5 objects better, but it provides the power of
320 metaclass programming as well.
324 If you're new to Moose, the best place to start is the
325 L<Moose::Manual> docs, followed by the L<Moose::Cookbook>. The intro
326 will show you what Moose is, and how it makes Perl 5 OO better.
328 The cookbook recipes on Moose basics will get you up to speed with
329 many of Moose's features quickly. Once you have an idea of what Moose
330 can do, you can use the API documentation to get more detail on
331 features which interest you.
333 =head2 Moose Extensions
335 The C<MooseX::> namespace is the official place to find Moose extensions.
336 These extensions can be found on the CPAN. The easiest way to find them
337 is to search for them (L<http://search.cpan.org/search?query=MooseX::>),
338 or to examine L<Task::Moose> which aims to keep an up-to-date, easily
339 installable list of Moose extensions.
343 Much of the Moose documentation has been translated into other languages.
349 Japanese docs can be found at
350 L<http://perldoc.perlassociation.org/pod/Moose-Doc-JA/index.html>. The
351 source POD files can be found in GitHub:
352 L<http://github.com/jpa/Moose-Doc-JA>
356 =head1 BUILDING CLASSES WITH MOOSE
358 Moose makes every attempt to provide as much convenience as possible during
359 class construction/definition, but still stay out of your way if you want it
360 to. Here are a few items to note when building classes with Moose.
362 When you C<use Moose>, Moose will set the class's parent class to
363 L<Moose::Object>, I<unless> the class using Moose already has a parent
364 class. In addition, specifying a parent with C<extends> will change the parent
367 Moose will also manage all attributes (including inherited ones) that are
368 defined with C<has>. And (assuming you call C<new>, which is inherited from
369 L<Moose::Object>) this includes properly initializing all instance slots,
370 setting defaults where appropriate, and performing any type constraint checking
373 =head1 PROVIDED METHODS
375 Moose provides a number of methods to all your classes, mostly through the
376 inheritance of L<Moose::Object>. There is however, one exception.
382 This is a method which provides access to the current class's metaclass.
386 =head1 EXPORTED FUNCTIONS
388 Moose will export a number of functions into the class's namespace which
389 may then be used to set up the class. These functions all work directly
390 on the current class.
394 =item B<extends (@superclasses)>
396 This function will set the superclass(es) for the current class.
398 This approach is recommended instead of C<use base>, because C<use base>
399 actually C<push>es onto the class's C<@ISA>, whereas C<extends> will
400 replace it. This is important to ensure that classes which do not have
401 superclasses still properly inherit from L<Moose::Object>.
403 Each superclass can be followed by a hash reference with options. Currently,
404 only L<-version|Class::MOP/Class Loading Options> is recognized:
406 extends 'My::Parent' => { -version => 0.01 },
407 'My::OtherParent' => { -version => 0.03 };
409 An exception will be thrown if the version requirements are not
412 =item B<with (@roles)>
414 This will apply a given set of C<@roles> to the local class.
416 Like with C<extends>, each specified role can be followed by a hash
417 reference with a L<-version|Class::MOP/Class Loading Options> option:
419 with 'My::Role' => { -version => 0.32 },
420 'My::Otherrole' => { -version => 0.23 };
422 The specified version requirements must be satisfied, otherwise an
423 exception will be thrown.
425 If your role takes options or arguments, they can be passed along in the
426 hash reference as well.
428 =item B<has $name|@$names =E<gt> %options>
430 This will install an attribute of a given C<$name> into the current class. If
431 the first parameter is an array reference, it will create an attribute for
432 every C<$name> in the list. The C<%options> will be passed to the constructor
433 for L<Moose::Meta::Attribute> (which inherits from L<Class::MOP::Attribute>),
434 so the full documentation for the valid options can be found there. These are
435 the most commonly used options:
439 =item I<is =E<gt> 'rw'|'ro'>
441 The I<is> option accepts either I<rw> (for read/write) or I<ro> (for read
442 only). These will create either a read/write accessor or a read-only
443 accessor respectively, using the same name as the C<$name> of the attribute.
445 If you need more control over how your accessors are named, you can
446 use the L<reader|Class::MOP::Attribute/reader>,
447 L<writer|Class::MOP::Attribute/writer> and
448 L<accessor|Class::MOP::Attribute/accessor> options inherited from
449 L<Class::MOP::Attribute>, however if you use those, you won't need the
452 =item I<isa =E<gt> $type_name>
454 The I<isa> option uses Moose's type constraint facilities to set up runtime
455 type checking for this attribute. Moose will perform the checks during class
456 construction, and within any accessors. The C<$type_name> argument must be a
457 string. The string may be either a class name or a type defined using
458 Moose's type definition features. (Refer to L<Moose::Util::TypeConstraints>
459 for information on how to define a new type, and how to retrieve type meta-data).
461 =item I<coerce =E<gt> (1|0)>
463 This will attempt to use coercion with the supplied type constraint to change
464 the value passed into any accessors or constructors. You B<must> supply a type
465 constraint, and that type constraint B<must> define a coercion. See
466 L<Moose::Cookbook::Basics::Recipe5> for an example.
468 =item I<does =E<gt> $role_name>
470 This will accept the name of a role which the value stored in this attribute
471 is expected to have consumed.
473 =item I<required =E<gt> (1|0)>
475 This marks the attribute as being required. This means a value must be
476 supplied during class construction, I<or> the attribute must be lazy
477 and have either a default or a builder. Note that c<required> does not
478 say anything about the attribute's value, which can be C<undef>.
480 =item I<weak_ref =E<gt> (1|0)>
482 This will tell the class to store the value of this attribute as a weakened
483 reference. If an attribute is a weakened reference, it B<cannot> also be
484 coerced. Note that when a weak ref expires, the attribute's value becomes
485 undefined, and is still considered to be set for purposes of predicate,
488 =item I<lazy =E<gt> (1|0)>
490 This will tell the class to not create this slot until absolutely necessary.
491 If an attribute is marked as lazy it B<must> have a default or builder
494 =item I<trigger =E<gt> $code>
496 The I<trigger> option is a CODE reference which will be called after
497 the value of the attribute is set. The CODE ref is passed the
498 instance itself, the updated value, and the original value if the
499 attribute was already set.
501 You B<can> have a trigger on a read-only attribute.
503 B<NOTE:> Triggers will only fire when you B<assign> to the attribute,
504 either in the constructor, or using the writer. Default and built values will
505 B<not> cause the trigger to be fired.
507 =item I<handles =E<gt> ARRAY | HASH | REGEXP | ROLE | ROLETYPE | DUCKTYPE | CODE>
509 The I<handles> option provides Moose classes with automated delegation features.
510 This is a pretty complex and powerful option. It accepts many different option
511 formats, each with its own benefits and drawbacks.
513 B<NOTE:> The class being delegated to does not need to be a Moose based class,
514 which is why this feature is especially useful when wrapping non-Moose classes.
516 All I<handles> option formats share the following traits:
518 You cannot override a locally defined method with a delegated method; an
519 exception will be thrown if you try. That is to say, if you define C<foo> in
520 your class, you cannot override it with a delegated C<foo>. This is almost never
521 something you would want to do, and if it is, you should do it by hand and not
524 You cannot override any of the methods found in Moose::Object, or the C<BUILD>
525 and C<DEMOLISH> methods. These will not throw an exception, but will silently
526 move on to the next method in the list. My reasoning for this is that you would
527 almost never want to do this, since it usually breaks your class. As with
528 overriding locally defined methods, if you do want to do this, you should do it
529 manually, not with Moose.
531 You do not I<need> to have a reader (or accessor) for the attribute in order
532 to delegate to it. Moose will create a means of accessing the value for you,
533 however this will be several times B<less> efficient then if you had given
534 the attribute a reader (or accessor) to use.
536 Below is the documentation for each option format:
542 This is the most common usage for I<handles>. You basically pass a list of
543 method names to be delegated, and Moose will install a delegation method
548 This is the second most common usage for I<handles>. Instead of a list of
549 method names, you pass a HASH ref where each key is the method name you
550 want installed locally, and its value is the name of the original method
551 in the class being delegated to.
553 This can be very useful for recursive classes like trees. Here is a
554 quick example (soon to be expanded into a Moose::Cookbook recipe):
559 has 'node' => (is => 'rw', isa => 'Any');
564 default => sub { [] }
572 parent_node => 'node',
573 siblings => 'children',
577 In this example, the Tree package gets C<parent_node> and C<siblings> methods,
578 which delegate to the C<node> and C<children> methods (respectively) of the Tree
579 instance stored in the C<parent> slot.
581 You may also use an array reference to curry arguments to the original method.
585 handles => { set_foo => [ set => 'foo' ] },
588 # $self->set_foo(...) calls $self->thing->set('foo', ...)
590 The first element of the array reference is the original method name, and the
591 rest is a list of curried arguments.
595 The regexp option works very similar to the ARRAY option, except that it builds
596 the list of methods for you. It starts by collecting all possible methods of the
597 class being delegated to, then filters that list using the regexp supplied here.
599 B<NOTE:> An I<isa> option is required when using the regexp option format. This
600 is so that we can determine (at compile time) the method list from the class.
601 Without an I<isa> this is just not possible.
603 =item C<ROLE> or C<ROLETYPE>
605 With the role option, you specify the name of a role or a
606 L<role type|Moose::Meta::TypeConstraint::Role> whose "interface" then becomes
607 the list of methods to handle. The "interface" can be defined as; the methods
608 of the role and any required methods of the role. It should be noted that this
609 does B<not> include any method modifiers or generated attribute methods (which
610 is consistent with role composition).
614 With the duck type option, you pass a duck type object whose "interface" then
615 becomes the list of methods to handle. The "interface" can be defined as the
616 list of methods passed to C<duck_type> to create a duck type object. For more
617 information on C<duck_type> please check
618 L<Moose::Util::TypeConstraints>.
622 This is the option to use when you really want to do something funky. You should
623 only use it if you really know what you are doing, as it involves manual
626 This takes a code reference, which should expect two arguments. The first is the
627 attribute meta-object this I<handles> is attached to. The second is the
628 metaclass of the class being delegated to. It expects you to return a hash (not
629 a HASH ref) of the methods you want mapped.
633 =item I<traits =E<gt> [ @role_names ]>
635 This tells Moose to take the list of C<@role_names> and apply them to the
636 attribute meta-object. Custom attribute metaclass traits are useful for
637 extending the capabilities of the I<has> keyword: they are the simplest way to
638 extend the MOP, but they are still a fairly advanced topic and too much to
641 See L<Metaclass and Trait Name Resolution> for details on how a trait name is
642 resolved to a role name.
644 Also see L<Moose::Cookbook::Meta::Recipe3> for a metaclass trait
647 =item I<builder> => Str
649 The value of this key is the name of the method that will be called to
650 obtain the value used to initialize the attribute. See the L<builder
651 option docs in Class::MOP::Attribute|Class::MOP::Attribute/builder>
652 and/or L<Moose::Cookbook::Basics::Recipe8> for more information.
654 =item I<default> => SCALAR | CODE
656 The value of this key is the default value which will initialize the attribute.
658 NOTE: If the value is a simple scalar (string or number), then it can
659 be just passed as is. However, if you wish to initialize it with a
660 HASH or ARRAY ref, then you need to wrap that inside a CODE reference.
661 See the L<default option docs in
662 Class::MOP::Attribute|Class::MOP::Attribute/default> for more
665 =item I<clearer> => Str
667 Creates a method allowing you to clear the value. See the L<clearer option
668 docs in Class::MOP::Attribute|Class::MOP::Attribute/clearer> for more
671 =item I<predicate> => Str
673 Creates a method to perform a basic test to see if a value has been set in the
674 attribute. See the L<predicate option docs in
675 Class::MOP::Attribute|Class::MOP::Attribute/predicate> for more information.
677 Note that the predicate will return true even for a C<weak_ref> attribute
678 whose value has expired.
680 =item I<documentation> => $string
682 An arbitrary string that can be retrieved later by calling C<<
683 $attr->documentation >>.
689 =item B<has +$name =E<gt> %options>
691 This is variation on the normal attribute creator C<has> which allows you to
692 clone and extend an attribute from a superclass or from a role. Here is an
693 example of the superclass usage:
701 default => 'Hello, I am a Foo'
709 has '+message' => (default => 'Hello I am My::Foo');
711 What is happening here is that B<My::Foo> is cloning the C<message> attribute
712 from its parent class B<Foo>, retaining the C<is =E<gt> 'rw'> and C<isa =E<gt>
713 'Str'> characteristics, but changing the value in C<default>.
715 Here is another example, but within the context of a role:
723 default => 'Hello, I am a Foo'
731 has '+message' => (default => 'Hello I am My::Foo');
733 In this case, we are basically taking the attribute which the role supplied
734 and altering it within the bounds of this feature.
736 Note that you can only extend an attribute from either a superclass or a role,
737 you cannot extend an attribute in a role that composes over an attribute from
740 Aside from where the attributes come from (one from superclass, the other
741 from a role), this feature works exactly the same. This feature is restricted
742 somewhat, so as to try and force at least I<some> sanity into it. Most options work the same, but there are some exceptions:
756 These options can be added, but cannot override a superclass definition.
760 You are allowed to B<add> additional traits to the C<traits> definition.
761 These traits will be composed into the attribute, but preexisting traits
762 B<are not> overridden, or removed.
766 =item B<before $name|@names|\@names|qr/.../ =E<gt> sub { ... }>
768 =item B<after $name|@names|\@names|qr/.../ =E<gt> sub { ... }>
770 =item B<around $name|@names|\@names|qr/.../ =E<gt> sub { ... }>
772 These three items are syntactic sugar for the before, after, and around method
773 modifier features that L<Class::MOP> provides. More information on these may be
774 found in L<Moose::Manual::MethodModifiers> and the
775 L<Class::MOP::Class documentation|Class::MOP::Class/"Method Modifiers">.
777 =item B<override ($name, &sub)>
779 An C<override> method is a way of explicitly saying "I am overriding this
780 method from my superclass". You can call C<super> within this method, and
781 it will work as expected. The same thing I<can> be accomplished with a normal
782 method call and the C<SUPER::> pseudo-package; it is really your choice.
786 The keyword C<super> is a no-op when called outside of an C<override> method. In
787 the context of an C<override> method, it will call the next most appropriate
788 superclass method with the same arguments as the original method.
790 =item B<augment ($name, &sub)>
792 An C<augment> method, is a way of explicitly saying "I am augmenting this
793 method from my superclass". Once again, the details of how C<inner> and
794 C<augment> work is best described in the L<Moose::Cookbook::Basics::Recipe6>.
798 The keyword C<inner>, much like C<super>, is a no-op outside of the context of
799 an C<augment> method. You can think of C<inner> as being the inverse of
800 C<super>; the details of how C<inner> and C<augment> work is best described in
801 the L<Moose::Cookbook::Basics::Recipe6>.
805 This is the C<Scalar::Util::blessed> function. It is highly recommended that
806 this is used instead of C<ref> anywhere you need to test for an object's class
811 This is the C<Carp::confess> function, and exported here for historical
818 When you use Moose, you can specify traits which will be applied to your
821 use Moose -traits => 'My::Trait';
823 This is very similar to the attribute traits feature. When you do
824 this, your class's C<meta> object will have the specified traits
825 applied to it. See L<Metaclass and Trait Name Resolution> for more
828 =head2 Metaclass and Trait Name Resolution
830 By default, when given a trait name, Moose simply tries to load a
831 class of the same name. If such a class does not exist, it then looks
832 for for a class matching
833 B<Moose::Meta::$type::Custom::Trait::$trait_name>. The C<$type>
834 variable here will be one of B<Attribute> or B<Class>, depending on
835 what the trait is being applied to.
837 If a class with this long name exists, Moose checks to see if it has
838 the method C<register_implementation>. This method is expected to
839 return the I<real> class name of the trait. If there is no
840 C<register_implementation> method, it will fall back to using
841 B<Moose::Meta::$type::Custom::Trait::$trait> as the trait name.
843 The lookup method for metaclasses is the same, except that it looks
844 for a class matching B<Moose::Meta::$type::Custom::$metaclass_name>.
846 If all this is confusing, take a look at
847 L<Moose::Cookbook::Meta::Recipe3>, which demonstrates how to create an
850 =head1 UNIMPORTING FUNCTIONS
854 Moose offers a way to remove the keywords it exports, through the C<unimport>
855 method. You simply have to say C<no Moose> at the bottom of your code for this
856 to work. Here is an example:
861 has 'first_name' => (is => 'rw', isa => 'Str');
862 has 'last_name' => (is => 'rw', isa => 'Str');
866 $self->first_name . ' ' . $self->last_name
869 no Moose; # keywords are removed from the Person package
871 =head1 EXTENDING AND EMBEDDING MOOSE
873 To learn more about extending Moose, we recommend checking out the
874 "Extending" recipes in the L<Moose::Cookbook>, starting with
875 L<Moose::Cookbook::Extending::Recipe1>, which provides an overview of
876 all the different ways you might extend Moose. L<Moose::Exporter> and
877 L<Moose::Util::MetaRole> are the modules which provide the majority of the
878 extension functionality, so reading their documentation should also be helpful.
880 =head2 The MooseX:: namespace
882 Generally if you're writing an extension I<for> Moose itself you'll want
883 to put your extension in the C<MooseX::> namespace. This namespace is
884 specifically for extensions that make Moose better or different in some
885 fundamental way. It is traditionally B<not> for a package that just happens
886 to use Moose. This namespace follows from the examples of the C<LWPx::>
887 and C<DBIx::> namespaces that perform the same function for C<LWP> and C<DBI>
890 =head1 METACLASS COMPATIBILITY AND MOOSE
892 Metaclass compatibility is a thorny subject. You should start by
893 reading the "About Metaclass compatibility" section in the
896 Moose will attempt to resolve a few cases of metaclass incompatibility
897 when you set the superclasses for a class, in addition to the cases that
898 C<Class::MOP> handles.
900 Moose tries to determine if the metaclasses only "differ by roles". This
901 means that the parent and child's metaclass share a common ancestor in
902 their respective hierarchies, and that the subclasses under the common
903 ancestor are only different because of role applications. This case is
904 actually fairly common when you mix and match various C<MooseX::*>
905 modules, many of which apply roles to the metaclass.
907 If the parent and child do differ by roles, Moose replaces the
908 metaclass in the child with a newly created metaclass. This metaclass
909 is a subclass of the parent's metaclass which does all of the roles that
910 the child's metaclass did before being replaced. Effectively, this
911 means the new metaclass does all of the roles done by both the
912 parent's and child's original metaclasses.
914 Ultimately, this is all transparent to you except in the case of an
915 unresolvable conflict.
923 It should be noted that C<super> and C<inner> B<cannot> be used in the same
924 method. However, they may be combined within the same class hierarchy; see
925 F<t/basics/override_augment_inner_super.t> for an example.
927 The reason for this is that C<super> is only valid within a method
928 with the C<override> modifier, and C<inner> will never be valid within an
929 C<override> method. In fact, C<augment> will skip over any C<override> methods
930 when searching for its appropriate C<inner>.
932 This might seem like a restriction, but I am of the opinion that keeping these
933 two features separate (yet interoperable) actually makes them easy to use, since
934 their behavior is then easier to predict. Time will tell whether I am right or
935 not (UPDATE: so far so good).
941 We offer both a mailing list and a very active IRC channel.
943 The mailing list is L<moose@perl.org>. You must be subscribed to send
944 a message. To subscribe, send an empty message to
945 L<moose-subscribe@perl.org>
947 You can also visit us at C<#moose> on L<irc://irc.perl.org/#moose>
948 This channel is quite active, and questions at all levels (on Moose-related
949 topics ;) are welcome.
951 =head1 ACKNOWLEDGEMENTS
955 =item I blame Sam Vilain for introducing me to the insanity that is meta-models.
957 =item I blame Audrey Tang for then encouraging my meta-model habit in #perl6.
959 =item Without Yuval "nothingmuch" Kogman this module would not be possible,
960 and it certainly wouldn't have this name ;P
962 =item The basis of the TypeContraints module was Rob Kinyon's idea
963 originally, I just ran with it.
965 =item Thanks to mst & chansen and the whole #moose posse for all the
966 early ideas/feature-requests/encouragement/bug-finding.
968 =item Thanks to David "Theory" Wheeler for meta-discussions and spelling fixes.
976 =item L<http://www.iinteractive.com/moose>
978 This is the official web home of Moose, it contains links to our public git repository
979 as well as links to a number of talks and articles on Moose and Moose related
982 =item The Moose is flying, a tutorial by Randal Schwartz
984 Part 1 - L<http://www.stonehenge.com/merlyn/LinuxMag/col94.html>
986 Part 2 - L<http://www.stonehenge.com/merlyn/LinuxMag/col95.html>
988 =item Several Moose extension modules in the C<MooseX::> namespace.
990 See L<http://search.cpan.org/search?query=MooseX::> for extensions.
998 =item The Art of the MetaObject Protocol
1000 I mention this in the L<Class::MOP> docs too, as this book was critical in
1001 the development of both modules and is highly recommended.
1009 =item L<http://www.cs.utah.edu/plt/publications/oopsla04-gff.pdf>
1011 This paper (suggested by lbr on #moose) was what lead to the implementation
1012 of the C<super>/C<override> and C<inner>/C<augment> features. If you really
1013 want to understand them, I suggest you read this.
1019 All complex software has bugs lurking in it, and this module is no
1022 Please report any bugs to C<bug-moose@rt.cpan.org>, or through the web
1023 interface at L<http://rt.cpan.org>.
1025 You can also discuss feature requests or possible bugs on the Moose mailing
1026 list (moose@perl.org) or on IRC at L<irc://irc.perl.org/#moose>.
1028 =head1 FEATURE REQUESTS
1030 We are very strict about what features we add to the Moose core, especially
1031 the user-visible features. Instead we have made sure that the underlying
1032 meta-system of Moose is as extensible as possible so that you can add your
1033 own features easily.
1035 That said, occasionally there is a feature needed in the meta-system
1036 to support your planned extension, in which case you should either
1037 email the mailing list (moose@perl.org) or join us on IRC at
1038 L<irc://irc.perl.org/#moose> to discuss. The
1039 L<Moose::Manual::Contributing> has more detail about how and when you
1044 There are only a few people with the rights to release a new version
1045 of Moose. The Moose Cabal are the people to go to with questions regarding
1046 the wider purview of Moose. They help maintain not just the code
1047 but the community as well.
1049 Stevan (stevan) Little E<lt>stevan@iinteractive.comE<gt>
1051 Jesse (doy) Luehrs E<lt>doy at tozt dot netE<gt>
1053 Yuval (nothingmuch) Kogman
1055 Shawn (sartak) Moore E<lt>sartak@bestpractical.comE<gt>
1057 Hans Dieter (confound) Pearcey E<lt>hdp@pobox.comE<gt>
1059 Chris (perigrin) Prather
1061 Florian Ragwitz E<lt>rafl@debian.orgE<gt>
1063 Dave (autarch) Rolsky E<lt>autarch@urth.orgE<gt>
1069 Adam (Alias) Kennedy
1071 Anders (Debolaz) Nor Berle
1073 Chris (perigrin) Prather
1075 Christian (chansen) Hansen
1079 Dylan Hardison (doc fixes)
1081 Eric (ewilhelm) Wilhelm
1085 Florian (rafl) Ragwitz
1087 Guillermo (groditi) Roditi
1093 Jess (castaway) Robinson
1095 Jonathan (jrockway) Rockway
1099 Nathan (kolibrie) Gray
1101 Paul (frodwith) Driver
1103 Piotr (dexter) Roszatycki
1107 Robert (phaylon) Sedlacek
1111 Sam (mugwump) Vilain
1113 Scott (konobi) McWhirter
1115 Shawn (Sartak) Moore
1117 Shlomi (rindolf) Fish
1121 Wallace (wreis) Reis
1123 ... and many other #moose folks