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,
138 my $class = $args{for_class}
139 or Moose->throw_error("Cannot call init_meta without specifying a for_class");
140 my $base_class = $args{base_class} || 'Moose::Object';
141 my $metaclass = $args{metaclass} || 'Moose::Meta::Class';
142 my $meta_name = exists $args{meta_name} ? $args{meta_name} : 'meta';
144 Moose->throw_error("The Metaclass $metaclass must be a subclass of Moose::Meta::Class.")
145 unless $metaclass->isa('Moose::Meta::Class');
147 # make a subtype for each Moose class
149 unless find_type_constraint($class);
153 if ( $meta = Class::MOP::get_metaclass_by_name($class) ) {
154 unless ( $meta->isa("Moose::Meta::Class") ) {
155 my $error_message = "$class already has a metaclass, but it does not inherit $metaclass ($meta).";
156 if ( $meta->isa('Moose::Meta::Role') ) {
157 Moose->throw_error($error_message . ' You cannot make the same thing a role and a class. Remove either Moose or Moose::Role.');
159 Moose->throw_error($error_message);
165 # now we check whether our ancestors have metaclass, and if so borrow that
166 my ( undef, @isa ) = @{ mro::get_linear_isa($class) };
168 foreach my $ancestor ( @isa ) {
169 my $ancestor_meta = Class::MOP::get_metaclass_by_name($ancestor) || next;
171 my $ancestor_meta_class = $ancestor_meta->_real_ref_name;
173 # if we have an ancestor metaclass that inherits $metaclass, we use
174 # that. This is like _fix_metaclass_incompatibility, but we can do it now.
176 # the case of having an ancestry is not very common, but arises in
178 unless ( $metaclass->isa( $ancestor_meta_class ) ) {
179 if ( $ancestor_meta_class->isa($metaclass) ) {
180 $metaclass = $ancestor_meta_class;
185 $meta = $metaclass->initialize($class);
188 if (defined $meta_name) {
189 # also check for inherited non moose 'meta' method?
190 my $existing = $meta->get_method($meta_name);
191 if ($existing && !$existing->isa('Class::MOP::Method::Meta')) {
192 Carp::cluck "Moose is overwriting an existing method named "
193 . "$meta_name in class $class with a method "
194 . "which returns the class's metaclass. If this is "
195 . "actually what you want, you should remove the "
196 . "existing method, otherwise, you should rename or "
197 . "disable this generated method using the "
198 . "'-meta_name' option to 'use Moose'.";
200 $meta->_add_meta_method($meta_name);
203 # make sure they inherit from Moose::Object
204 $meta->superclasses($base_class)
205 unless $meta->superclasses();
210 # This may be used in some older MooseX extensions.
212 goto &Moose::Exporter::_get_caller;
215 ## make 'em all immutable
218 inline_constructor => 1,
219 constructor_name => "_new",
220 # these are Class::MOP accessors, so they need inlining
221 inline_accessors => 1
222 ) for grep { $_->is_mutable }
225 Moose::Meta::Attribute
227 Moose::Meta::Instance
229 Moose::Meta::TypeCoercion
230 Moose::Meta::TypeCoercion::Union
233 Moose::Meta::Method::Constructor
234 Moose::Meta::Method::Destructor
235 Moose::Meta::Method::Overridden
236 Moose::Meta::Method::Augmented
239 Moose::Meta::Role::Attribute
240 Moose::Meta::Role::Method
241 Moose::Meta::Role::Method::Required
242 Moose::Meta::Role::Method::Conflicting
244 Moose::Meta::Role::Composite
246 Moose::Meta::Role::Application
247 Moose::Meta::Role::Application::RoleSummation
248 Moose::Meta::Role::Application::ToClass
249 Moose::Meta::Role::Application::ToRole
250 Moose::Meta::Role::Application::ToInstance
254 inline_constructor => 0,
255 constructor_name => undef,
256 # these are Class::MOP accessors, so they need inlining
257 inline_accessors => 1
258 ) for grep { $_->is_mutable }
261 Moose::Meta::Method::Accessor
262 Moose::Meta::Method::Delegation
263 Moose::Meta::Mixin::AttributeCore
268 # ABSTRACT: A postmodern object system for Perl 5
277 use Moose; # automatically turns on strict and warnings
279 has 'x' => (is => 'rw', isa => 'Int');
280 has 'y' => (is => 'rw', isa => 'Int');
293 has 'z' => (is => 'rw', isa => 'Int');
295 after 'clear' => sub {
302 Moose is an extension of the Perl 5 object system.
304 The main goal of Moose is to make Perl 5 Object Oriented programming
305 easier, more consistent, and less tedious. With Moose you can think
306 more about what you want to do and less about the mechanics of OOP.
308 Additionally, Moose is built on top of L<Class::MOP>, which is a
309 metaclass system for Perl 5. This means that Moose not only makes
310 building normal Perl 5 objects better, but it provides the power of
311 metaclass programming as well.
315 If you're new to Moose, the best place to start is the
316 L<Moose::Manual> docs, followed by the L<Moose::Cookbook>. The intro
317 will show you what Moose is, and how it makes Perl 5 OO better.
319 The cookbook recipes on Moose basics will get you up to speed with
320 many of Moose's features quickly. Once you have an idea of what Moose
321 can do, you can use the API documentation to get more detail on
322 features which interest you.
324 =head2 Moose Extensions
326 The C<MooseX::> namespace is the official place to find Moose extensions.
327 These extensions can be found on the CPAN. The easiest way to find them
328 is to search for them (L<http://search.cpan.org/search?query=MooseX::>),
329 or to examine L<Task::Moose> which aims to keep an up-to-date, easily
330 installable list of Moose extensions.
334 Much of the Moose documentation has been translated into other languages.
340 Japanese docs can be found at
341 L<http://perldoc.perlassociation.org/pod/Moose-Doc-JA/index.html>. The
342 source POD files can be found in GitHub:
343 L<http://github.com/jpa/Moose-Doc-JA>
347 =head1 BUILDING CLASSES WITH MOOSE
349 Moose makes every attempt to provide as much convenience as possible during
350 class construction/definition, but still stay out of your way if you want it
351 to. Here are a few items to note when building classes with Moose.
353 When you C<use Moose>, Moose will set the class's parent class to
354 L<Moose::Object>, I<unless> the class using Moose already has a parent
355 class. In addition, specifying a parent with C<extends> will change the parent
358 Moose will also manage all attributes (including inherited ones) that are
359 defined with C<has>. And (assuming you call C<new>, which is inherited from
360 L<Moose::Object>) this includes properly initializing all instance slots,
361 setting defaults where appropriate, and performing any type constraint checking
364 =head1 PROVIDED METHODS
366 Moose provides a number of methods to all your classes, mostly through the
367 inheritance of L<Moose::Object>. There is however, one exception.
373 This is a method which provides access to the current class's metaclass.
377 =head1 EXPORTED FUNCTIONS
379 Moose will export a number of functions into the class's namespace which
380 may then be used to set up the class. These functions all work directly
381 on the current class.
385 =item B<extends (@superclasses)>
387 This function will set the superclass(es) for the current class.
389 This approach is recommended instead of C<use base>, because C<use base>
390 actually C<push>es onto the class's C<@ISA>, whereas C<extends> will
391 replace it. This is important to ensure that classes which do not have
392 superclasses still properly inherit from L<Moose::Object>.
394 Each superclass can be followed by a hash reference with options. Currently,
395 only L<-version|Class::MOP/Class Loading Options> is recognized:
397 extends 'My::Parent' => { -version => 0.01 },
398 'My::OtherParent' => { -version => 0.03 };
400 An exception will be thrown if the version requirements are not
403 =item B<with (@roles)>
405 This will apply a given set of C<@roles> to the local class.
407 Like with C<extends>, each specified role can be followed by a hash
408 reference with a L<-version|Class::MOP/Class Loading Options> option:
410 with 'My::Role' => { -version => 0.32 },
411 'My::Otherrole' => { -version => 0.23 };
413 The specified version requirements must be satisfied, otherwise an
414 exception will be thrown.
416 If your role takes options or arguments, they can be passed along in the
417 hash reference as well.
419 =item B<has $name|@$names =E<gt> %options>
421 This will install an attribute of a given C<$name> into the current class. If
422 the first parameter is an array reference, it will create an attribute for
423 every C<$name> in the list. The C<%options> will be passed to the constructor
424 for L<Moose::Meta::Attribute> (which inherits from L<Class::MOP::Attribute>),
425 so the full documentation for the valid options can be found there. These are
426 the most commonly used options:
430 =item I<is =E<gt> 'rw'|'ro'>
432 The I<is> option accepts either I<rw> (for read/write) or I<ro> (for read
433 only). These will create either a read/write accessor or a read-only
434 accessor respectively, using the same name as the C<$name> of the attribute.
436 If you need more control over how your accessors are named, you can
437 use the L<reader|Class::MOP::Attribute/reader>,
438 L<writer|Class::MOP::Attribute/writer> and
439 L<accessor|Class::MOP::Attribute/accessor> options inherited from
440 L<Class::MOP::Attribute>, however if you use those, you won't need the
443 =item I<isa =E<gt> $type_name>
445 The I<isa> option uses Moose's type constraint facilities to set up runtime
446 type checking for this attribute. Moose will perform the checks during class
447 construction, and within any accessors. The C<$type_name> argument must be a
448 string. The string may be either a class name or a type defined using
449 Moose's type definition features. (Refer to L<Moose::Util::TypeConstraints>
450 for information on how to define a new type, and how to retrieve type meta-data).
452 =item I<coerce =E<gt> (1|0)>
454 This will attempt to use coercion with the supplied type constraint to change
455 the value passed into any accessors or constructors. You B<must> supply a type
456 constraint, and that type constraint B<must> define a coercion. See
457 L<Moose::Cookbook::Basics::Recipe5> for an example.
459 =item I<does =E<gt> $role_name>
461 This will accept the name of a role which the value stored in this attribute
462 is expected to have consumed.
464 =item I<required =E<gt> (1|0)>
466 This marks the attribute as being required. This means a value must be
467 supplied during class construction, I<or> the attribute must be lazy
468 and have either a default or a builder. Note that c<required> does not
469 say anything about the attribute's value, which can be C<undef>.
471 =item I<weak_ref =E<gt> (1|0)>
473 This will tell the class to store the value of this attribute as a weakened
474 reference. If an attribute is a weakened reference, it B<cannot> also be
475 coerced. Note that when a weak ref expires, the attribute's value becomes
476 undefined, and is still considered to be set for purposes of predicate,
479 =item I<lazy =E<gt> (1|0)>
481 This will tell the class to not create this slot until absolutely necessary.
482 If an attribute is marked as lazy it B<must> have a default or builder
485 =item I<trigger =E<gt> $code>
487 The I<trigger> option is a CODE reference which will be called after
488 the value of the attribute is set. The CODE ref is passed the
489 instance itself, the updated value, and the original value if the
490 attribute was already set.
492 You B<can> have a trigger on a read-only attribute.
494 B<NOTE:> Triggers will only fire when you B<assign> to the attribute,
495 either in the constructor, or using the writer. Default and built values will
496 B<not> cause the trigger to be fired.
498 =item I<handles =E<gt> ARRAY | HASH | REGEXP | ROLE | ROLETYPE | DUCKTYPE | CODE>
500 The I<handles> option provides Moose classes with automated delegation features.
501 This is a pretty complex and powerful option. It accepts many different option
502 formats, each with its own benefits and drawbacks.
504 B<NOTE:> The class being delegated to does not need to be a Moose based class,
505 which is why this feature is especially useful when wrapping non-Moose classes.
507 All I<handles> option formats share the following traits:
509 You cannot override a locally defined method with a delegated method; an
510 exception will be thrown if you try. That is to say, if you define C<foo> in
511 your class, you cannot override it with a delegated C<foo>. This is almost never
512 something you would want to do, and if it is, you should do it by hand and not
515 You cannot override any of the methods found in Moose::Object, or the C<BUILD>
516 and C<DEMOLISH> methods. These will not throw an exception, but will silently
517 move on to the next method in the list. My reasoning for this is that you would
518 almost never want to do this, since it usually breaks your class. As with
519 overriding locally defined methods, if you do want to do this, you should do it
520 manually, not with Moose.
522 You do not I<need> to have a reader (or accessor) for the attribute in order
523 to delegate to it. Moose will create a means of accessing the value for you,
524 however this will be several times B<less> efficient then if you had given
525 the attribute a reader (or accessor) to use.
527 Below is the documentation for each option format:
533 This is the most common usage for I<handles>. You basically pass a list of
534 method names to be delegated, and Moose will install a delegation method
539 This is the second most common usage for I<handles>. Instead of a list of
540 method names, you pass a HASH ref where each key is the method name you
541 want installed locally, and its value is the name of the original method
542 in the class being delegated to.
544 This can be very useful for recursive classes like trees. Here is a
545 quick example (soon to be expanded into a Moose::Cookbook recipe):
550 has 'node' => (is => 'rw', isa => 'Any');
555 default => sub { [] }
563 parent_node => 'node',
564 siblings => 'children',
568 In this example, the Tree package gets C<parent_node> and C<siblings> methods,
569 which delegate to the C<node> and C<children> methods (respectively) of the Tree
570 instance stored in the C<parent> slot.
572 You may also use an array reference to curry arguments to the original method.
576 handles => { set_foo => [ set => 'foo' ] },
579 # $self->set_foo(...) calls $self->thing->set('foo', ...)
581 The first element of the array reference is the original method name, and the
582 rest is a list of curried arguments.
586 The regexp option works very similar to the ARRAY option, except that it builds
587 the list of methods for you. It starts by collecting all possible methods of the
588 class being delegated to, then filters that list using the regexp supplied here.
590 B<NOTE:> An I<isa> option is required when using the regexp option format. This
591 is so that we can determine (at compile time) the method list from the class.
592 Without an I<isa> this is just not possible.
594 =item C<ROLE> or C<ROLETYPE>
596 With the role option, you specify the name of a role or a
597 L<role type|Moose::Meta::TypeConstraint::Role> whose "interface" then becomes
598 the list of methods to handle. The "interface" can be defined as; the methods
599 of the role and any required methods of the role. It should be noted that this
600 does B<not> include any method modifiers or generated attribute methods (which
601 is consistent with role composition).
605 With the duck type option, you pass a duck type object whose "interface" then
606 becomes the list of methods to handle. The "interface" can be defined as the
607 list of methods passed to C<duck_type> to create a duck type object. For more
608 information on C<duck_type> please check
609 L<Moose::Util::TypeConstraints>.
613 This is the option to use when you really want to do something funky. You should
614 only use it if you really know what you are doing, as it involves manual
617 This takes a code reference, which should expect two arguments. The first is the
618 attribute meta-object this I<handles> is attached to. The second is the
619 metaclass of the class being delegated to. It expects you to return a hash (not
620 a HASH ref) of the methods you want mapped.
624 =item I<traits =E<gt> [ @role_names ]>
626 This tells Moose to take the list of C<@role_names> and apply them to the
627 attribute meta-object. Custom attribute metaclass traits are useful for
628 extending the capabilities of the I<has> keyword: they are the simplest way to
629 extend the MOP, but they are still a fairly advanced topic and too much to
632 See L<Metaclass and Trait Name Resolution> for details on how a trait name is
633 resolved to a role name.
635 Also see L<Moose::Cookbook::Meta::Recipe3> for a metaclass trait
638 =item I<builder> => Str
640 The value of this key is the name of the method that will be called to
641 obtain the value used to initialize the attribute. See the L<builder
642 option docs in Class::MOP::Attribute|Class::MOP::Attribute/builder>
643 and/or L<Moose::Cookbook::Basics::Recipe8> for more information.
645 =item I<default> => SCALAR | CODE
647 The value of this key is the default value which will initialize the attribute.
649 NOTE: If the value is a simple scalar (string or number), then it can
650 be just passed as is. However, if you wish to initialize it with a
651 HASH or ARRAY ref, then you need to wrap that inside a CODE reference.
652 See the L<default option docs in
653 Class::MOP::Attribute|Class::MOP::Attribute/default> for more
656 =item I<clearer> => Str
658 Creates a method allowing you to clear the value. See the L<clearer option
659 docs in Class::MOP::Attribute|Class::MOP::Attribute/clearer> for more
662 =item I<predicate> => Str
664 Creates a method to perform a basic test to see if a value has been set in the
665 attribute. See the L<predicate option docs in
666 Class::MOP::Attribute|Class::MOP::Attribute/predicate> for more information.
668 Note that the predicate will return true even for a C<weak_ref> attribute
669 whose value has expired.
671 =item I<documentation> => $string
673 An arbitrary string that can be retrieved later by calling C<<
674 $attr->documentation >>.
680 =item B<has +$name =E<gt> %options>
682 This is variation on the normal attribute creator C<has> which allows you to
683 clone and extend an attribute from a superclass or from a role. Here is an
684 example of the superclass usage:
692 default => 'Hello, I am a Foo'
700 has '+message' => (default => 'Hello I am My::Foo');
702 What is happening here is that B<My::Foo> is cloning the C<message> attribute
703 from its parent class B<Foo>, retaining the C<is =E<gt> 'rw'> and C<isa =E<gt>
704 'Str'> characteristics, but changing the value in C<default>.
706 Here is another example, but within the context of a role:
714 default => 'Hello, I am a Foo'
722 has '+message' => (default => 'Hello I am My::Foo');
724 In this case, we are basically taking the attribute which the role supplied
725 and altering it within the bounds of this feature.
727 Note that you can only extend an attribute from either a superclass or a role,
728 you cannot extend an attribute in a role that composes over an attribute from
731 Aside from where the attributes come from (one from superclass, the other
732 from a role), this feature works exactly the same. This feature is restricted
733 somewhat, so as to try and force at least I<some> sanity into it. Most options work the same, but there are some exceptions:
747 These options can be added, but cannot override a superclass definition.
751 You are allowed to B<add> additional traits to the C<traits> definition.
752 These traits will be composed into the attribute, but preexisting traits
753 B<are not> overridden, or removed.
757 =item B<before $name|@names|\@names|qr/.../ =E<gt> sub { ... }>
759 =item B<after $name|@names|\@names|qr/.../ =E<gt> sub { ... }>
761 =item B<around $name|@names|\@names|qr/.../ =E<gt> sub { ... }>
763 These three items are syntactic sugar for the before, after, and around method
764 modifier features that L<Class::MOP> provides. More information on these may be
765 found in L<Moose::Manual::MethodModifiers> and the
766 L<Class::MOP::Class documentation|Class::MOP::Class/"Method Modifiers">.
768 =item B<override ($name, &sub)>
770 An C<override> method is a way of explicitly saying "I am overriding this
771 method from my superclass". You can call C<super> within this method, and
772 it will work as expected. The same thing I<can> be accomplished with a normal
773 method call and the C<SUPER::> pseudo-package; it is really your choice.
777 The keyword C<super> is a no-op when called outside of an C<override> method. In
778 the context of an C<override> method, it will call the next most appropriate
779 superclass method with the same arguments as the original method.
781 =item B<augment ($name, &sub)>
783 An C<augment> method, is a way of explicitly saying "I am augmenting this
784 method from my superclass". Once again, the details of how C<inner> and
785 C<augment> work is best described in the L<Moose::Cookbook::Basics::Recipe6>.
789 The keyword C<inner>, much like C<super>, is a no-op outside of the context of
790 an C<augment> method. You can think of C<inner> as being the inverse of
791 C<super>; the details of how C<inner> and C<augment> work is best described in
792 the L<Moose::Cookbook::Basics::Recipe6>.
796 This is the C<Scalar::Util::blessed> function. It is highly recommended that
797 this is used instead of C<ref> anywhere you need to test for an object's class
802 This is the C<Carp::confess> function, and exported here for historical
809 When you use Moose, you can specify traits which will be applied to your
812 use Moose -traits => 'My::Trait';
814 This is very similar to the attribute traits feature. When you do
815 this, your class's C<meta> object will have the specified traits
816 applied to it. See L<Metaclass and Trait Name Resolution> for more
819 =head2 Metaclass and Trait Name Resolution
821 By default, when given a trait name, Moose simply tries to load a
822 class of the same name. If such a class does not exist, it then looks
823 for for a class matching
824 B<Moose::Meta::$type::Custom::Trait::$trait_name>. The C<$type>
825 variable here will be one of B<Attribute> or B<Class>, depending on
826 what the trait is being applied to.
828 If a class with this long name exists, Moose checks to see if it has
829 the method C<register_implementation>. This method is expected to
830 return the I<real> class name of the trait. If there is no
831 C<register_implementation> method, it will fall back to using
832 B<Moose::Meta::$type::Custom::Trait::$trait> as the trait name.
834 The lookup method for metaclasses is the same, except that it looks
835 for a class matching B<Moose::Meta::$type::Custom::$metaclass_name>.
837 If all this is confusing, take a look at
838 L<Moose::Cookbook::Meta::Recipe3>, which demonstrates how to create an
841 =head1 UNIMPORTING FUNCTIONS
845 Moose offers a way to remove the keywords it exports, through the C<unimport>
846 method. You simply have to say C<no Moose> at the bottom of your code for this
847 to work. Here is an example:
852 has 'first_name' => (is => 'rw', isa => 'Str');
853 has 'last_name' => (is => 'rw', isa => 'Str');
857 $self->first_name . ' ' . $self->last_name
860 no Moose; # keywords are removed from the Person package
862 =head1 EXTENDING AND EMBEDDING MOOSE
864 To learn more about extending Moose, we recommend checking out the
865 "Extending" recipes in the L<Moose::Cookbook>, starting with
866 L<Moose::Cookbook::Extending::Recipe1>, which provides an overview of
867 all the different ways you might extend Moose. L<Moose::Exporter> and
868 L<Moose::Util::MetaRole> are the modules which provide the majority of the
869 extension functionality, so reading their documentation should also be helpful.
871 =head2 The MooseX:: namespace
873 Generally if you're writing an extension I<for> Moose itself you'll want
874 to put your extension in the C<MooseX::> namespace. This namespace is
875 specifically for extensions that make Moose better or different in some
876 fundamental way. It is traditionally B<not> for a package that just happens
877 to use Moose. This namespace follows from the examples of the C<LWPx::>
878 and C<DBIx::> namespaces that perform the same function for C<LWP> and C<DBI>
881 =head1 METACLASS COMPATIBILITY AND MOOSE
883 Metaclass compatibility is a thorny subject. You should start by
884 reading the "About Metaclass compatibility" section in the
887 Moose will attempt to resolve a few cases of metaclass incompatibility
888 when you set the superclasses for a class, in addition to the cases that
889 C<Class::MOP> handles.
891 Moose tries to determine if the metaclasses only "differ by roles". This
892 means that the parent and child's metaclass share a common ancestor in
893 their respective hierarchies, and that the subclasses under the common
894 ancestor are only different because of role applications. This case is
895 actually fairly common when you mix and match various C<MooseX::*>
896 modules, many of which apply roles to the metaclass.
898 If the parent and child do differ by roles, Moose replaces the
899 metaclass in the child with a newly created metaclass. This metaclass
900 is a subclass of the parent's metaclass which does all of the roles that
901 the child's metaclass did before being replaced. Effectively, this
902 means the new metaclass does all of the roles done by both the
903 parent's and child's original metaclasses.
905 Ultimately, this is all transparent to you except in the case of an
906 unresolvable conflict.
914 It should be noted that C<super> and C<inner> B<cannot> be used in the same
915 method. However, they may be combined within the same class hierarchy; see
916 F<t/basics/override_augment_inner_super.t> for an example.
918 The reason for this is that C<super> is only valid within a method
919 with the C<override> modifier, and C<inner> will never be valid within an
920 C<override> method. In fact, C<augment> will skip over any C<override> methods
921 when searching for its appropriate C<inner>.
923 This might seem like a restriction, but I am of the opinion that keeping these
924 two features separate (yet interoperable) actually makes them easy to use, since
925 their behavior is then easier to predict. Time will tell whether I am right or
926 not (UPDATE: so far so good).
932 We offer both a mailing list and a very active IRC channel.
934 The mailing list is L<moose@perl.org>. You must be subscribed to send
935 a message. To subscribe, send an empty message to
936 L<moose-subscribe@perl.org>
938 You can also visit us at C<#moose> on L<irc://irc.perl.org/#moose>
939 This channel is quite active, and questions at all levels (on Moose-related
940 topics ;) are welcome.
942 =head1 ACKNOWLEDGEMENTS
946 =item I blame Sam Vilain for introducing me to the insanity that is meta-models.
948 =item I blame Audrey Tang for then encouraging my meta-model habit in #perl6.
950 =item Without Yuval "nothingmuch" Kogman this module would not be possible,
951 and it certainly wouldn't have this name ;P
953 =item The basis of the TypeContraints module was Rob Kinyon's idea
954 originally, I just ran with it.
956 =item Thanks to mst & chansen and the whole #moose posse for all the
957 early ideas/feature-requests/encouragement/bug-finding.
959 =item Thanks to David "Theory" Wheeler for meta-discussions and spelling fixes.
967 =item L<http://www.iinteractive.com/moose>
969 This is the official web home of Moose, it contains links to our public git repository
970 as well as links to a number of talks and articles on Moose and Moose related
973 =item The Moose is flying, a tutorial by Randal Schwartz
975 Part 1 - L<http://www.stonehenge.com/merlyn/LinuxMag/col94.html>
977 Part 2 - L<http://www.stonehenge.com/merlyn/LinuxMag/col95.html>
979 =item Several Moose extension modules in the C<MooseX::> namespace.
981 See L<http://search.cpan.org/search?query=MooseX::> for extensions.
989 =item The Art of the MetaObject Protocol
991 I mention this in the L<Class::MOP> docs too, as this book was critical in
992 the development of both modules and is highly recommended.
1000 =item L<http://www.cs.utah.edu/plt/publications/oopsla04-gff.pdf>
1002 This paper (suggested by lbr on #moose) was what lead to the implementation
1003 of the C<super>/C<override> and C<inner>/C<augment> features. If you really
1004 want to understand them, I suggest you read this.
1010 All complex software has bugs lurking in it, and this module is no
1013 Please report any bugs to C<bug-moose@rt.cpan.org>, or through the web
1014 interface at L<http://rt.cpan.org>.
1016 You can also discuss feature requests or possible bugs on the Moose mailing
1017 list (moose@perl.org) or on IRC at L<irc://irc.perl.org/#moose>.
1019 =head1 FEATURE REQUESTS
1021 We are very strict about what features we add to the Moose core, especially
1022 the user-visible features. Instead we have made sure that the underlying
1023 meta-system of Moose is as extensible as possible so that you can add your
1024 own features easily.
1026 That said, occasionally there is a feature needed in the meta-system
1027 to support your planned extension, in which case you should either
1028 email the mailing list (moose@perl.org) or join us on IRC at
1029 L<irc://irc.perl.org/#moose> to discuss. The
1030 L<Moose::Manual::Contributing> has more detail about how and when you
1035 There are only a few people with the rights to release a new version
1036 of Moose. The Moose Cabal are the people to go to with questions regarding
1037 the wider purview of Moose. They help maintain not just the code
1038 but the community as well.
1040 Stevan (stevan) Little E<lt>stevan@iinteractive.comE<gt>
1042 Jesse (doy) Luehrs E<lt>doy at tozt dot netE<gt>
1044 Yuval (nothingmuch) Kogman
1046 Shawn (sartak) Moore E<lt>sartak@bestpractical.comE<gt>
1048 Hans Dieter (confound) Pearcey E<lt>hdp@pobox.comE<gt>
1050 Chris (perigrin) Prather
1052 Florian Ragwitz E<lt>rafl@debian.orgE<gt>
1054 Dave (autarch) Rolsky E<lt>autarch@urth.orgE<gt>
1060 Adam (Alias) Kennedy
1062 Anders (Debolaz) Nor Berle
1064 Chris (perigrin) Prather
1066 Christian (chansen) Hansen
1070 Dylan Hardison (doc fixes)
1072 Eric (ewilhelm) Wilhelm
1076 Florian (rafl) Ragwitz
1078 Guillermo (groditi) Roditi
1084 Jess (castaway) Robinson
1086 Jonathan (jrockway) Rockway
1090 Nathan (kolibrie) Gray
1092 Paul (frodwith) Driver
1094 Piotr (dexter) Roszatycki
1098 Robert (phaylon) Sedlacek
1102 Sam (mugwump) Vilain
1104 Scott (konobi) McWhirter
1106 Shawn (Sartak) Moore
1108 Shlomi (rindolf) Fish
1112 Wallace (wreis) Reis
1114 ... and many other #moose folks