7 use Scalar::Util 'blessed';
10 use Moose::Deprecated;
15 use Moose::Meta::Class;
16 use Moose::Meta::TypeConstraint;
17 use Moose::Meta::TypeCoercion;
18 use Moose::Meta::Attribute;
19 use Moose::Meta::Instance;
23 use Moose::Meta::Role;
24 use Moose::Meta::Role::Composite;
25 use Moose::Meta::Role::Application;
26 use Moose::Meta::Role::Application::RoleSummation;
27 use Moose::Meta::Role::Application::ToClass;
28 use Moose::Meta::Role::Application::ToRole;
29 use Moose::Meta::Role::Application::ToInstance;
31 use Moose::Util::TypeConstraints;
34 use Moose::Meta::Attribute::Native;
45 Moose->throw_error("Must derive at least one class") unless @_;
47 # this checks the metaclass to make sure
48 # it is correct, sometimes it can get out
49 # of sync when the classes are being built
50 $meta->superclasses(@_);
54 Moose::Util::apply_all_roles(shift, @_);
61 Moose->throw_error('Usage: has \'name\' => ( key => value, ... )')
64 my %options = ( definition_context => Moose::Util::_caller_info(), @_ );
65 my $attrs = ( ref($name) eq 'ARRAY' ) ? $name : [ ($name) ];
66 $meta->add_attribute( $_, %options ) for @$attrs;
70 Moose::Util::add_method_modifier(shift, 'before', \@_);
74 Moose::Util::add_method_modifier(shift, 'after', \@_);
78 Moose::Util::add_method_modifier(shift, 'around', \@_);
86 # This check avoids a recursion loop - see
87 # t/bugs/super_recursion.t
88 return if defined $SUPER_PACKAGE && $SUPER_PACKAGE ne caller();
89 return unless $SUPER_BODY; $SUPER_BODY->(@SUPER_ARGS);
94 my ( $name, $method ) = @_;
95 $meta->add_override_method_modifier( $name => $method );
100 our ( %INNER_BODY, %INNER_ARGS );
102 if ( my $body = $INNER_BODY{$pkg} ) {
103 my @args = @{ $INNER_ARGS{$pkg} };
104 local $INNER_ARGS{$pkg};
105 local $INNER_BODY{$pkg};
106 return $body->(@args);
114 my ( $name, $method ) = @_;
115 $meta->add_augment_method_modifier( $name => $method );
118 Moose::Exporter->setup_import_methods(
120 qw( extends with has before after around override augment )
125 \&Scalar::Util::blessed,
130 # This used to be called as a function. This hack preserves
131 # backwards compatibility.
132 if ( $_[0] ne __PACKAGE__ ) {
133 Moose::Deprecated::deprecated(
134 feature => 'Moose::init_meta',
135 message => 'Calling Moose::init_meta as a function is deprecated.'
136 . ' Doing so will throw an error in Moose 2.0200.'
139 return __PACKAGE__->init_meta(
149 my $class = $args{for_class}
150 or Moose->throw_error("Cannot call init_meta without specifying a for_class");
151 my $base_class = $args{base_class} || 'Moose::Object';
152 my $metaclass = $args{metaclass} || 'Moose::Meta::Class';
153 my $meta_name = exists $args{meta_name} ? $args{meta_name} : 'meta';
155 Moose->throw_error("The Metaclass $metaclass must be a subclass of Moose::Meta::Class.")
156 unless $metaclass->isa('Moose::Meta::Class');
158 # make a subtype for each Moose class
160 unless find_type_constraint($class);
164 if ( $meta = Class::MOP::get_metaclass_by_name($class) ) {
165 unless ( $meta->isa("Moose::Meta::Class") ) {
166 my $error_message = "$class already has a metaclass, but it does not inherit $metaclass ($meta).";
167 if ( $meta->isa('Moose::Meta::Role') ) {
168 Moose->throw_error($error_message . ' You cannot make the same thing a role and a class. Remove either Moose or Moose::Role.');
170 Moose->throw_error($error_message);
176 # now we check whether our ancestors have metaclass, and if so borrow that
177 my ( undef, @isa ) = @{ mro::get_linear_isa($class) };
179 foreach my $ancestor ( @isa ) {
180 my $ancestor_meta = Class::MOP::get_metaclass_by_name($ancestor) || next;
182 my $ancestor_meta_class = $ancestor_meta->_real_ref_name;
184 # if we have an ancestor metaclass that inherits $metaclass, we use
185 # that. This is like _fix_metaclass_incompatibility, but we can do it now.
187 # the case of having an ancestry is not very common, but arises in
189 unless ( $metaclass->isa( $ancestor_meta_class ) ) {
190 if ( $ancestor_meta_class->isa($metaclass) ) {
191 $metaclass = $ancestor_meta_class;
196 $meta = $metaclass->initialize($class);
199 if (defined $meta_name) {
200 # also check for inherited non moose 'meta' method?
201 my $existing = $meta->get_method($meta_name);
202 if ($existing && !$existing->isa('Class::MOP::Method::Meta')) {
203 Carp::cluck "Moose is overwriting an existing method named "
204 . "$meta_name in class $class with a method "
205 . "which returns the class's metaclass. If this is "
206 . "actually what you want, you should remove the "
207 . "existing method, otherwise, you should rename or "
208 . "disable this generated method using the "
209 . "'-meta_name' option to 'use Moose'.";
211 $meta->_add_meta_method($meta_name);
214 # make sure they inherit from Moose::Object
215 $meta->superclasses($base_class)
216 unless $meta->superclasses();
221 # This may be used in some older MooseX extensions.
223 goto &Moose::Exporter::_get_caller;
226 ## make 'em all immutable
229 inline_constructor => 1,
230 constructor_name => "_new",
231 # these are Class::MOP accessors, so they need inlining
232 inline_accessors => 1
233 ) for grep { $_->is_mutable }
236 Moose::Meta::Attribute
238 Moose::Meta::Instance
240 Moose::Meta::TypeCoercion
241 Moose::Meta::TypeCoercion::Union
244 Moose::Meta::Method::Accessor
245 Moose::Meta::Method::Constructor
246 Moose::Meta::Method::Destructor
247 Moose::Meta::Method::Overridden
248 Moose::Meta::Method::Augmented
251 Moose::Meta::Role::Attribute
252 Moose::Meta::Role::Method
253 Moose::Meta::Role::Method::Required
254 Moose::Meta::Role::Method::Conflicting
256 Moose::Meta::Role::Composite
258 Moose::Meta::Role::Application
259 Moose::Meta::Role::Application::RoleSummation
260 Moose::Meta::Role::Application::ToClass
261 Moose::Meta::Role::Application::ToRole
262 Moose::Meta::Role::Application::ToInstance
265 Moose::Meta::Mixin::AttributeCore->meta->make_immutable(
266 inline_constructor => 0,
267 constructor_name => undef,
272 # ABSTRACT: A postmodern object system for Perl 5
281 use Moose; # automatically turns on strict and warnings
283 has 'x' => (is => 'rw', isa => 'Int');
284 has 'y' => (is => 'rw', isa => 'Int');
297 has 'z' => (is => 'rw', isa => 'Int');
299 after 'clear' => sub {
306 Moose is an extension of the Perl 5 object system.
308 The main goal of Moose is to make Perl 5 Object Oriented programming
309 easier, more consistent, and less tedious. With Moose you can think
310 more about what you want to do and less about the mechanics of OOP.
312 Additionally, Moose is built on top of L<Class::MOP>, which is a
313 metaclass system for Perl 5. This means that Moose not only makes
314 building normal Perl 5 objects better, but it provides the power of
315 metaclass programming as well.
319 If you're new to Moose, the best place to start is the
320 L<Moose::Manual> docs, followed by the L<Moose::Cookbook>. The intro
321 will show you what Moose is, and how it makes Perl 5 OO better.
323 The cookbook recipes on Moose basics will get you up to speed with
324 many of Moose's features quickly. Once you have an idea of what Moose
325 can do, you can use the API documentation to get more detail on
326 features which interest you.
328 =head2 Moose Extensions
330 The C<MooseX::> namespace is the official place to find Moose extensions.
331 These extensions can be found on the CPAN. The easiest way to find them
332 is to search for them (L<http://search.cpan.org/search?query=MooseX::>),
333 or to examine L<Task::Moose> which aims to keep an up-to-date, easily
334 installable list of Moose extensions.
338 Much of the Moose documentation has been translated into other languages.
344 Japanese docs can be found at
345 L<http://perldoc.perlassociation.org/pod/Moose-Doc-JA/index.html>. The
346 source POD files can be found in GitHub:
347 L<http://github.com/jpa/Moose-Doc-JA>
351 =head1 BUILDING CLASSES WITH MOOSE
353 Moose makes every attempt to provide as much convenience as possible during
354 class construction/definition, but still stay out of your way if you want it
355 to. Here are a few items to note when building classes with Moose.
357 When you C<use Moose>, Moose will set the class's parent class to
358 L<Moose::Object>, I<unless> the class using Moose already has a parent
359 class. In addition, specifying a parent with C<extends> will change the parent
362 Moose will also manage all attributes (including inherited ones) that are
363 defined with C<has>. And (assuming you call C<new>, which is inherited from
364 L<Moose::Object>) this includes properly initializing all instance slots,
365 setting defaults where appropriate, and performing any type constraint checking
368 =head1 PROVIDED METHODS
370 Moose provides a number of methods to all your classes, mostly through the
371 inheritance of L<Moose::Object>. There is however, one exception.
377 This is a method which provides access to the current class's metaclass.
381 =head1 EXPORTED FUNCTIONS
383 Moose will export a number of functions into the class's namespace which
384 may then be used to set up the class. These functions all work directly
385 on the current class.
389 =item B<extends (@superclasses)>
391 This function will set the superclass(es) for the current class.
393 This approach is recommended instead of C<use base>, because C<use base>
394 actually C<push>es onto the class's C<@ISA>, whereas C<extends> will
395 replace it. This is important to ensure that classes which do not have
396 superclasses still properly inherit from L<Moose::Object>.
398 Each superclass can be followed by a hash reference with options. Currently,
399 only L<-version|Class::MOP/Class Loading Options> is recognized:
401 extends 'My::Parent' => { -version => 0.01 },
402 'My::OtherParent' => { -version => 0.03 };
404 An exception will be thrown if the version requirements are not
407 =item B<with (@roles)>
409 This will apply a given set of C<@roles> to the local class.
411 Like with C<extends>, each specified role can be followed by a hash
412 reference with a L<-version|Class::MOP/Class Loading Options> option:
414 with 'My::Role' => { -version => 0.32 },
415 'My::Otherrole' => { -version => 0.23 };
417 The specified version requirements must be satisfied, otherwise an
418 exception will be thrown.
420 If your role takes options or arguments, they can be passed along in the
421 hash reference as well.
423 =item B<has $name|@$names =E<gt> %options>
425 This will install an attribute of a given C<$name> into the current class. If
426 the first parameter is an array reference, it will create an attribute for
427 every C<$name> in the list. The C<%options> will be passed to the constructor
428 for L<Moose::Meta::Attribute> (which inherits from L<Class::MOP::Attribute>),
429 so the full documentation for the valid options can be found there. These are
430 the most commonly used options:
434 =item I<is =E<gt> 'rw'|'ro'>
436 The I<is> option accepts either I<rw> (for read/write) or I<ro> (for read
437 only). These will create either a read/write accessor or a read-only
438 accessor respectively, using the same name as the C<$name> of the attribute.
440 If you need more control over how your accessors are named, you can
441 use the L<reader|Class::MOP::Attribute/reader>,
442 L<writer|Class::MOP::Attribute/writer> and
443 L<accessor|Class::MOP::Attribute/accessor> options inherited from
444 L<Class::MOP::Attribute>, however if you use those, you won't need the
447 =item I<isa =E<gt> $type_name>
449 The I<isa> option uses Moose's type constraint facilities to set up runtime
450 type checking for this attribute. Moose will perform the checks during class
451 construction, and within any accessors. The C<$type_name> argument must be a
452 string. The string may be either a class name or a type defined using
453 Moose's type definition features. (Refer to L<Moose::Util::TypeConstraints>
454 for information on how to define a new type, and how to retrieve type meta-data).
456 =item I<coerce =E<gt> (1|0)>
458 This will attempt to use coercion with the supplied type constraint to change
459 the value passed into any accessors or constructors. You B<must> supply a type
460 constraint, and that type constraint B<must> define a coercion. See
461 L<Moose::Cookbook::Basics::Recipe5> for an example.
463 =item I<does =E<gt> $role_name>
465 This will accept the name of a role which the value stored in this attribute
466 is expected to have consumed.
468 =item I<required =E<gt> (1|0)>
470 This marks the attribute as being required. This means a value must be
471 supplied during class construction, I<or> the attribute must be lazy
472 and have either a default or a builder. Note that c<required> does not
473 say anything about the attribute's value, which can be C<undef>.
475 =item I<weak_ref =E<gt> (1|0)>
477 This will tell the class to store the value of this attribute as a weakened
478 reference. If an attribute is a weakened reference, it B<cannot> also be
479 coerced. Note that when a weak ref expires, the attribute's value becomes
480 undefined, and is still considered to be set for purposes of predicate,
483 =item I<lazy =E<gt> (1|0)>
485 This will tell the class to not create this slot until absolutely necessary.
486 If an attribute is marked as lazy it B<must> have a default or builder
489 =item I<trigger =E<gt> $code>
491 The I<trigger> option is a CODE reference which will be called after
492 the value of the attribute is set. The CODE ref is passed the
493 instance itself, the updated value, and the original value if the
494 attribute was already set.
496 You B<can> have a trigger on a read-only attribute.
498 B<NOTE:> Triggers will only fire when you B<assign> to the attribute,
499 either in the constructor, or using the writer. Default and built values will
500 B<not> cause the trigger to be fired.
502 =item I<handles =E<gt> ARRAY | HASH | REGEXP | ROLE | ROLETYPE | DUCKTYPE | CODE>
504 The I<handles> option provides Moose classes with automated delegation features.
505 This is a pretty complex and powerful option. It accepts many different option
506 formats, each with its own benefits and drawbacks.
508 B<NOTE:> The class being delegated to does not need to be a Moose based class,
509 which is why this feature is especially useful when wrapping non-Moose classes.
511 All I<handles> option formats share the following traits:
513 You cannot override a locally defined method with a delegated method; an
514 exception will be thrown if you try. That is to say, if you define C<foo> in
515 your class, you cannot override it with a delegated C<foo>. This is almost never
516 something you would want to do, and if it is, you should do it by hand and not
519 You cannot override any of the methods found in Moose::Object, or the C<BUILD>
520 and C<DEMOLISH> methods. These will not throw an exception, but will silently
521 move on to the next method in the list. My reasoning for this is that you would
522 almost never want to do this, since it usually breaks your class. As with
523 overriding locally defined methods, if you do want to do this, you should do it
524 manually, not with Moose.
526 You do not I<need> to have a reader (or accessor) for the attribute in order
527 to delegate to it. Moose will create a means of accessing the value for you,
528 however this will be several times B<less> efficient then if you had given
529 the attribute a reader (or accessor) to use.
531 Below is the documentation for each option format:
537 This is the most common usage for I<handles>. You basically pass a list of
538 method names to be delegated, and Moose will install a delegation method
543 This is the second most common usage for I<handles>. Instead of a list of
544 method names, you pass a HASH ref where each key is the method name you
545 want installed locally, and its value is the name of the original method
546 in the class being delegated to.
548 This can be very useful for recursive classes like trees. Here is a
549 quick example (soon to be expanded into a Moose::Cookbook recipe):
554 has 'node' => (is => 'rw', isa => 'Any');
559 default => sub { [] }
567 parent_node => 'node',
568 siblings => 'children',
572 In this example, the Tree package gets C<parent_node> and C<siblings> methods,
573 which delegate to the C<node> and C<children> methods (respectively) of the Tree
574 instance stored in the C<parent> slot.
576 You may also use an array reference to curry arguments to the original method.
580 handles => { set_foo => [ set => 'foo' ] },
583 # $self->set_foo(...) calls $self->thing->set('foo', ...)
585 The first element of the array reference is the original method name, and the
586 rest is a list of curried arguments.
590 The regexp option works very similar to the ARRAY option, except that it builds
591 the list of methods for you. It starts by collecting all possible methods of the
592 class being delegated to, then filters that list using the regexp supplied here.
594 B<NOTE:> An I<isa> option is required when using the regexp option format. This
595 is so that we can determine (at compile time) the method list from the class.
596 Without an I<isa> this is just not possible.
598 =item C<ROLE> or C<ROLETYPE>
600 With the role option, you specify the name of a role or a
601 L<role type|Moose::Meta::TypeConstraint::Role> whose "interface" then becomes
602 the list of methods to handle. The "interface" can be defined as; the methods
603 of the role and any required methods of the role. It should be noted that this
604 does B<not> include any method modifiers or generated attribute methods (which
605 is consistent with role composition).
609 With the duck type option, you pass a duck type object whose "interface" then
610 becomes the list of methods to handle. The "interface" can be defined as the
611 list of methods passed to C<duck_type> to create a duck type object. For more
612 information on C<duck_type> please check
613 L<Moose::Util::TypeConstraints>.
617 This is the option to use when you really want to do something funky. You should
618 only use it if you really know what you are doing, as it involves manual
621 This takes a code reference, which should expect two arguments. The first is the
622 attribute meta-object this I<handles> is attached to. The second is the
623 metaclass of the class being delegated to. It expects you to return a hash (not
624 a HASH ref) of the methods you want mapped.
628 =item I<traits =E<gt> [ @role_names ]>
630 This tells Moose to take the list of C<@role_names> and apply them to the
631 attribute meta-object. Custom attribute metaclass traits are useful for
632 extending the capabilities of the I<has> keyword: they are the simplest way to
633 extend the MOP, but they are still a fairly advanced topic and too much to
636 See L<Metaclass and Trait Name Resolution> for details on how a trait name is
637 resolved to a role name.
639 Also see L<Moose::Cookbook::Meta::Recipe3> for a metaclass trait
642 =item I<builder> => Str
644 The value of this key is the name of the method that will be called to
645 obtain the value used to initialize the attribute. See the L<builder
646 option docs in Class::MOP::Attribute|Class::MOP::Attribute/builder>
647 and/or L<Moose::Cookbook::Basics::Recipe8> for more information.
649 =item I<default> => SCALAR | CODE
651 The value of this key is the default value which will initialize the attribute.
653 NOTE: If the value is a simple scalar (string or number), then it can
654 be just passed as is. However, if you wish to initialize it with a
655 HASH or ARRAY ref, then you need to wrap that inside a CODE reference.
656 See the L<default option docs in
657 Class::MOP::Attribute|Class::MOP::Attribute/default> for more
660 =item I<clearer> => Str
662 Creates a method allowing you to clear the value. See the L<clearer option
663 docs in Class::MOP::Attribute|Class::MOP::Attribute/clearer> for more
666 =item I<predicate> => Str
668 Creates a method to perform a basic test to see if a value has been set in the
669 attribute. See the L<predicate option docs in
670 Class::MOP::Attribute|Class::MOP::Attribute/predicate> for more information.
672 Note that the predicate will return true even for a C<weak_ref> attribute
673 whose value has expired.
675 =item I<documentation> => $string
677 An arbitrary string that can be retrieved later by calling C<<
678 $attr->documentation >>.
684 =item B<has +$name =E<gt> %options>
686 This is variation on the normal attribute creator C<has> which allows you to
687 clone and extend an attribute from a superclass or from a role. Here is an
688 example of the superclass usage:
696 default => 'Hello, I am a Foo'
704 has '+message' => (default => 'Hello I am My::Foo');
706 What is happening here is that B<My::Foo> is cloning the C<message> attribute
707 from its parent class B<Foo>, retaining the C<is =E<gt> 'rw'> and C<isa =E<gt>
708 'Str'> characteristics, but changing the value in C<default>.
710 Here is another example, but within the context of a role:
718 default => 'Hello, I am a Foo'
726 has '+message' => (default => 'Hello I am My::Foo');
728 In this case, we are basically taking the attribute which the role supplied
729 and altering it within the bounds of this feature.
731 Note that you can only extend an attribute from either a superclass or a role,
732 you cannot extend an attribute in a role that composes over an attribute from
735 Aside from where the attributes come from (one from superclass, the other
736 from a role), this feature works exactly the same. This feature is restricted
737 somewhat, so as to try and force at least I<some> sanity into it. Most options work the same, but there are some exceptions:
751 These options can be added, but cannot override a superclass definition.
755 You are allowed to B<add> additional traits to the C<traits> definition.
756 These traits will be composed into the attribute, but preexisting traits
757 B<are not> overridden, or removed.
761 =item B<before $name|@names|\@names|qr/.../ =E<gt> sub { ... }>
763 =item B<after $name|@names|\@names|qr/.../ =E<gt> sub { ... }>
765 =item B<around $name|@names|\@names|qr/.../ =E<gt> sub { ... }>
767 These three items are syntactic sugar for the before, after, and around method
768 modifier features that L<Class::MOP> provides. More information on these may be
769 found in L<Moose::Manual::MethodModifiers> and the
770 L<Class::MOP::Class documentation|Class::MOP::Class/"Method Modifiers">.
772 =item B<override ($name, &sub)>
774 An C<override> method is a way of explicitly saying "I am overriding this
775 method from my superclass". You can call C<super> within this method, and
776 it will work as expected. The same thing I<can> be accomplished with a normal
777 method call and the C<SUPER::> pseudo-package; it is really your choice.
781 The keyword C<super> is a no-op when called outside of an C<override> method. In
782 the context of an C<override> method, it will call the next most appropriate
783 superclass method with the same arguments as the original method.
785 =item B<augment ($name, &sub)>
787 An C<augment> method, is a way of explicitly saying "I am augmenting this
788 method from my superclass". Once again, the details of how C<inner> and
789 C<augment> work is best described in the L<Moose::Cookbook::Basics::Recipe6>.
793 The keyword C<inner>, much like C<super>, is a no-op outside of the context of
794 an C<augment> method. You can think of C<inner> as being the inverse of
795 C<super>; the details of how C<inner> and C<augment> work is best described in
796 the L<Moose::Cookbook::Basics::Recipe6>.
800 This is the C<Scalar::Util::blessed> function. It is highly recommended that
801 this is used instead of C<ref> anywhere you need to test for an object's class
806 This is the C<Carp::confess> function, and exported here for historical
813 When you use Moose, you can specify traits which will be applied to your
816 use Moose -traits => 'My::Trait';
818 This is very similar to the attribute traits feature. When you do
819 this, your class's C<meta> object will have the specified traits
820 applied to it. See L<Metaclass and Trait Name Resolution> for more
823 =head2 Metaclass and Trait Name Resolution
825 By default, when given a trait name, Moose simply tries to load a
826 class of the same name. If such a class does not exist, it then looks
827 for for a class matching
828 B<Moose::Meta::$type::Custom::Trait::$trait_name>. The C<$type>
829 variable here will be one of B<Attribute> or B<Class>, depending on
830 what the trait is being applied to.
832 If a class with this long name exists, Moose checks to see if it has
833 the method C<register_implementation>. This method is expected to
834 return the I<real> class name of the trait. If there is no
835 C<register_implementation> method, it will fall back to using
836 B<Moose::Meta::$type::Custom::Trait::$trait> as the trait name.
838 The lookup method for metaclasses is the same, except that it looks
839 for a class matching B<Moose::Meta::$type::Custom::$metaclass_name>.
841 If all this is confusing, take a look at
842 L<Moose::Cookbook::Meta::Recipe3>, which demonstrates how to create an
845 =head1 UNIMPORTING FUNCTIONS
849 Moose offers a way to remove the keywords it exports, through the C<unimport>
850 method. You simply have to say C<no Moose> at the bottom of your code for this
851 to work. Here is an example:
856 has 'first_name' => (is => 'rw', isa => 'Str');
857 has 'last_name' => (is => 'rw', isa => 'Str');
861 $self->first_name . ' ' . $self->last_name
864 no Moose; # keywords are removed from the Person package
866 =head1 EXTENDING AND EMBEDDING MOOSE
868 To learn more about extending Moose, we recommend checking out the
869 "Extending" recipes in the L<Moose::Cookbook>, starting with
870 L<Moose::Cookbook::Extending::Recipe1>, which provides an overview of
871 all the different ways you might extend Moose. L<Moose::Exporter> and
872 L<Moose::Util::MetaRole> are the modules which provide the majority of the
873 extension functionality, so reading their documentation should also be helpful.
875 =head2 The MooseX:: namespace
877 Generally if you're writing an extension I<for> Moose itself you'll want
878 to put your extension in the C<MooseX::> namespace. This namespace is
879 specifically for extensions that make Moose better or different in some
880 fundamental way. It is traditionally B<not> for a package that just happens
881 to use Moose. This namespace follows from the examples of the C<LWPx::>
882 and C<DBIx::> namespaces that perform the same function for C<LWP> and C<DBI>
885 =head1 METACLASS COMPATIBILITY AND MOOSE
887 Metaclass compatibility is a thorny subject. You should start by
888 reading the "About Metaclass compatibility" section in the
891 Moose will attempt to resolve a few cases of metaclass incompatibility
892 when you set the superclasses for a class, in addition to the cases that
893 C<Class::MOP> handles.
895 Moose tries to determine if the metaclasses only "differ by roles". This
896 means that the parent and child's metaclass share a common ancestor in
897 their respective hierarchies, and that the subclasses under the common
898 ancestor are only different because of role applications. This case is
899 actually fairly common when you mix and match various C<MooseX::*>
900 modules, many of which apply roles to the metaclass.
902 If the parent and child do differ by roles, Moose replaces the
903 metaclass in the child with a newly created metaclass. This metaclass
904 is a subclass of the parent's metaclass which does all of the roles that
905 the child's metaclass did before being replaced. Effectively, this
906 means the new metaclass does all of the roles done by both the
907 parent's and child's original metaclasses.
909 Ultimately, this is all transparent to you except in the case of an
910 unresolvable conflict.
918 It should be noted that C<super> and C<inner> B<cannot> be used in the same
919 method. However, they may be combined within the same class hierarchy; see
920 F<t/basics/override_augment_inner_super.t> for an example.
922 The reason for this is that C<super> is only valid within a method
923 with the C<override> modifier, and C<inner> will never be valid within an
924 C<override> method. In fact, C<augment> will skip over any C<override> methods
925 when searching for its appropriate C<inner>.
927 This might seem like a restriction, but I am of the opinion that keeping these
928 two features separate (yet interoperable) actually makes them easy to use, since
929 their behavior is then easier to predict. Time will tell whether I am right or
930 not (UPDATE: so far so good).
936 We offer both a mailing list and a very active IRC channel.
938 The mailing list is L<moose@perl.org>. You must be subscribed to send
939 a message. To subscribe, send an empty message to
940 L<moose-subscribe@perl.org>
942 You can also visit us at C<#moose> on L<irc://irc.perl.org/#moose>
943 This channel is quite active, and questions at all levels (on Moose-related
944 topics ;) are welcome.
946 =head1 ACKNOWLEDGEMENTS
950 =item I blame Sam Vilain for introducing me to the insanity that is meta-models.
952 =item I blame Audrey Tang for then encouraging my meta-model habit in #perl6.
954 =item Without Yuval "nothingmuch" Kogman this module would not be possible,
955 and it certainly wouldn't have this name ;P
957 =item The basis of the TypeContraints module was Rob Kinyon's idea
958 originally, I just ran with it.
960 =item Thanks to mst & chansen and the whole #moose posse for all the
961 early ideas/feature-requests/encouragement/bug-finding.
963 =item Thanks to David "Theory" Wheeler for meta-discussions and spelling fixes.
971 =item L<http://www.iinteractive.com/moose>
973 This is the official web home of Moose, it contains links to our public git repository
974 as well as links to a number of talks and articles on Moose and Moose related
977 =item The Moose is flying, a tutorial by Randal Schwartz
979 Part 1 - L<http://www.stonehenge.com/merlyn/LinuxMag/col94.html>
981 Part 2 - L<http://www.stonehenge.com/merlyn/LinuxMag/col95.html>
983 =item Several Moose extension modules in the C<MooseX::> namespace.
985 See L<http://search.cpan.org/search?query=MooseX::> for extensions.
993 =item The Art of the MetaObject Protocol
995 I mention this in the L<Class::MOP> docs too, as this book was critical in
996 the development of both modules and is highly recommended.
1004 =item L<http://www.cs.utah.edu/plt/publications/oopsla04-gff.pdf>
1006 This paper (suggested by lbr on #moose) was what lead to the implementation
1007 of the C<super>/C<override> and C<inner>/C<augment> features. If you really
1008 want to understand them, I suggest you read this.
1014 All complex software has bugs lurking in it, and this module is no
1017 Please report any bugs to C<bug-moose@rt.cpan.org>, or through the web
1018 interface at L<http://rt.cpan.org>.
1020 You can also discuss feature requests or possible bugs on the Moose mailing
1021 list (moose@perl.org) or on IRC at L<irc://irc.perl.org/#moose>.
1023 =head1 FEATURE REQUESTS
1025 We are very strict about what features we add to the Moose core, especially
1026 the user-visible features. Instead we have made sure that the underlying
1027 meta-system of Moose is as extensible as possible so that you can add your
1028 own features easily.
1030 That said, occasionally there is a feature needed in the meta-system
1031 to support your planned extension, in which case you should either
1032 email the mailing list (moose@perl.org) or join us on IRC at
1033 L<irc://irc.perl.org/#moose> to discuss. The
1034 L<Moose::Manual::Contributing> has more detail about how and when you
1039 There are only a few people with the rights to release a new version
1040 of Moose. The Moose Cabal are the people to go to with questions regarding
1041 the wider purview of Moose. They help maintain not just the code
1042 but the community as well.
1044 Stevan (stevan) Little E<lt>stevan@iinteractive.comE<gt>
1046 Jesse (doy) Luehrs E<lt>doy at tozt dot netE<gt>
1048 Yuval (nothingmuch) Kogman
1050 Shawn (sartak) Moore E<lt>sartak@bestpractical.comE<gt>
1052 Hans Dieter (confound) Pearcey E<lt>hdp@pobox.comE<gt>
1054 Chris (perigrin) Prather
1056 Florian Ragwitz E<lt>rafl@debian.orgE<gt>
1058 Dave (autarch) Rolsky E<lt>autarch@urth.orgE<gt>
1064 Adam (Alias) Kennedy
1066 Anders (Debolaz) Nor Berle
1068 Chris (perigrin) Prather
1070 Christian (chansen) Hansen
1074 Dylan Hardison (doc fixes)
1076 Eric (ewilhelm) Wilhelm
1080 Florian (rafl) Ragwitz
1082 Guillermo (groditi) Roditi
1088 Jess (castaway) Robinson
1090 Jonathan (jrockway) Rockway
1094 Nathan (kolibrie) Gray
1096 Paul (frodwith) Driver
1098 Piotr (dexter) Roszatycki
1102 Robert (phaylon) Sedlacek
1106 Sam (mugwump) Vilain
1108 Scott (konobi) McWhirter
1110 Shawn (Sartak) Moore
1112 Shlomi (rindolf) Fish
1116 Wallace (wreis) Reis
1118 ... and many other #moose folks