7 use Scalar::Util 'blessed';
9 use Class::Load 'is_class_loaded';
12 use Moose::Deprecated;
18 die "Class::MOP version $Moose::VERSION required--this is version $Class::MOP::VERSION"
19 if $Moose::VERSION && $Class::MOP::VERSION ne $Moose::VERSION;
22 use Moose::Meta::Class;
23 use Moose::Meta::TypeConstraint;
24 use Moose::Meta::TypeCoercion;
25 use Moose::Meta::Attribute;
26 use Moose::Meta::Instance;
30 use Moose::Meta::Role;
31 use Moose::Meta::Role::Composite;
32 use Moose::Meta::Role::Application;
33 use Moose::Meta::Role::Application::RoleSummation;
34 use Moose::Meta::Role::Application::ToClass;
35 use Moose::Meta::Role::Application::ToRole;
36 use Moose::Meta::Role::Application::ToInstance;
38 use Moose::Util::TypeConstraints;
41 use Moose::Meta::Attribute::Native;
52 Moose->throw_error("Must derive at least one class") unless @_;
54 # this checks the metaclass to make sure
55 # it is correct, sometimes it can get out
56 # of sync when the classes are being built
57 $meta->superclasses(@_);
61 Moose::Util::apply_all_roles(shift, @_);
68 Moose->throw_error('Usage: has \'name\' => ( key => value, ... )')
71 my %options = ( definition_context => Moose::Util::_caller_info(), @_ );
72 my $attrs = ( ref($name) eq 'ARRAY' ) ? $name : [ ($name) ];
73 $meta->add_attribute( $_, %options ) for @$attrs;
77 Moose::Util::add_method_modifier(shift, 'before', \@_);
81 Moose::Util::add_method_modifier(shift, 'after', \@_);
85 Moose::Util::add_method_modifier(shift, 'around', \@_);
93 # This check avoids a recursion loop - see
94 # t/bugs/super_recursion.t
95 return if defined $SUPER_PACKAGE && $SUPER_PACKAGE ne caller();
96 return unless $SUPER_BODY; $SUPER_BODY->(@SUPER_ARGS);
101 my ( $name, $method ) = @_;
102 $meta->add_override_method_modifier( $name => $method );
107 our ( %INNER_BODY, %INNER_ARGS );
109 if ( my $body = $INNER_BODY{$pkg} ) {
110 my @args = @{ $INNER_ARGS{$pkg} };
111 local $INNER_ARGS{$pkg};
112 local $INNER_BODY{$pkg};
113 return $body->(@args);
121 my ( $name, $method ) = @_;
122 $meta->add_augment_method_modifier( $name => $method );
125 Moose::Exporter->setup_import_methods(
127 qw( extends with has before after around override augment )
132 \&Scalar::Util::blessed,
140 my $class = $args{for_class}
141 or Moose->throw_error("Cannot call init_meta without specifying a for_class");
142 my $base_class = $args{base_class} || 'Moose::Object';
143 my $metaclass = $args{metaclass} || 'Moose::Meta::Class';
144 my $meta_name = exists $args{meta_name} ? $args{meta_name} : 'meta';
146 Moose->throw_error("The Metaclass $metaclass must be loaded. (Perhaps you forgot to 'use $metaclass'?)")
147 unless is_class_loaded($metaclass);
149 Moose->throw_error("The Metaclass $metaclass must be a subclass of Moose::Meta::Class.")
150 unless $metaclass->isa('Moose::Meta::Class');
152 # make a subtype for each Moose class
154 unless find_type_constraint($class);
158 if ( $meta = Class::MOP::get_metaclass_by_name($class) ) {
159 unless ( $meta->isa("Moose::Meta::Class") ) {
160 my $error_message = "$class already has a metaclass, but it does not inherit $metaclass ($meta).";
161 if ( $meta->isa('Moose::Meta::Role') ) {
162 Moose->throw_error($error_message . ' You cannot make the same thing a role and a class. Remove either Moose or Moose::Role.');
164 Moose->throw_error($error_message);
170 # now we check whether our ancestors have metaclass, and if so borrow that
171 my ( undef, @isa ) = @{ mro::get_linear_isa($class) };
173 foreach my $ancestor ( @isa ) {
174 my $ancestor_meta = Class::MOP::get_metaclass_by_name($ancestor) || next;
176 my $ancestor_meta_class = $ancestor_meta->_real_ref_name;
178 # if we have an ancestor metaclass that inherits $metaclass, we use
179 # that. This is like _fix_metaclass_incompatibility, but we can do it now.
181 # the case of having an ancestry is not very common, but arises in
183 unless ( $metaclass->isa( $ancestor_meta_class ) ) {
184 if ( $ancestor_meta_class->isa($metaclass) ) {
185 $metaclass = $ancestor_meta_class;
190 $meta = $metaclass->initialize($class);
193 if (defined $meta_name) {
194 # also check for inherited non moose 'meta' method?
195 my $existing = $meta->get_method($meta_name);
196 if ($existing && !$existing->isa('Class::MOP::Method::Meta')) {
197 Carp::cluck "Moose is overwriting an existing method named "
198 . "$meta_name in class $class with a method "
199 . "which returns the class's metaclass. If this is "
200 . "actually what you want, you should remove the "
201 . "existing method, otherwise, you should rename or "
202 . "disable this generated method using the "
203 . "'-meta_name' option to 'use Moose'.";
205 $meta->_add_meta_method($meta_name);
208 # make sure they inherit from Moose::Object
209 $meta->superclasses($base_class)
210 unless $meta->superclasses();
215 # This may be used in some older MooseX extensions.
217 goto &Moose::Exporter::_get_caller;
220 ## make 'em all immutable
223 inline_constructor => 1,
224 constructor_name => "_new",
225 # these are Class::MOP accessors, so they need inlining
226 inline_accessors => 1
227 ) for grep { $_->is_mutable }
230 Moose::Meta::Attribute
232 Moose::Meta::Instance
234 Moose::Meta::TypeCoercion
235 Moose::Meta::TypeCoercion::Union
238 Moose::Meta::Method::Constructor
239 Moose::Meta::Method::Destructor
240 Moose::Meta::Method::Overridden
241 Moose::Meta::Method::Augmented
244 Moose::Meta::Role::Attribute
245 Moose::Meta::Role::Method
246 Moose::Meta::Role::Method::Required
247 Moose::Meta::Role::Method::Conflicting
249 Moose::Meta::Role::Composite
251 Moose::Meta::Role::Application
252 Moose::Meta::Role::Application::RoleSummation
253 Moose::Meta::Role::Application::ToClass
254 Moose::Meta::Role::Application::ToRole
255 Moose::Meta::Role::Application::ToInstance
259 inline_constructor => 0,
260 constructor_name => undef,
261 # these are Class::MOP accessors, so they need inlining
262 inline_accessors => 1
263 ) for grep { $_->is_mutable }
266 Moose::Meta::Method::Accessor
267 Moose::Meta::Method::Delegation
268 Moose::Meta::Mixin::AttributeCore
273 # ABSTRACT: A postmodern object system for Perl 5
282 use Moose; # automatically turns on strict and warnings
284 has 'x' => (is => 'rw', isa => 'Int');
285 has 'y' => (is => 'rw', isa => 'Int');
298 has 'z' => (is => 'rw', isa => 'Int');
300 after 'clear' => sub {
307 Moose is an extension of the Perl 5 object system.
309 The main goal of Moose is to make Perl 5 Object Oriented programming
310 easier, more consistent, and less tedious. With Moose you can think
311 more about what you want to do and less about the mechanics of OOP.
313 Additionally, Moose is built on top of L<Class::MOP>, which is a
314 metaclass system for Perl 5. This means that Moose not only makes
315 building normal Perl 5 objects better, but it provides the power of
316 metaclass programming as well.
320 If you're new to Moose, the best place to start is the
321 L<Moose::Manual> docs, followed by the L<Moose::Cookbook>. The intro
322 will show you what Moose is, and how it makes Perl 5 OO better.
324 The cookbook recipes on Moose basics will get you up to speed with
325 many of Moose's features quickly. Once you have an idea of what Moose
326 can do, you can use the API documentation to get more detail on
327 features which interest you.
329 =head2 Moose Extensions
331 The C<MooseX::> namespace is the official place to find Moose extensions.
332 These extensions can be found on the CPAN. The easiest way to find them
333 is to search for them (L<http://search.cpan.org/search?query=MooseX::>),
334 or to examine L<Task::Moose> which aims to keep an up-to-date, easily
335 installable list of Moose extensions.
339 Much of the Moose documentation has been translated into other languages.
345 Japanese docs can be found at
346 L<http://perldoc.perlassociation.org/pod/Moose-Doc-JA/index.html>. The
347 source POD files can be found in GitHub:
348 L<http://github.com/jpa/Moose-Doc-JA>
352 =head1 BUILDING CLASSES WITH MOOSE
354 Moose makes every attempt to provide as much convenience as possible during
355 class construction/definition, but still stay out of your way if you want it
356 to. Here are a few items to note when building classes with Moose.
358 When you C<use Moose>, Moose will set the class's parent class to
359 L<Moose::Object>, I<unless> the class using Moose already has a parent
360 class. In addition, specifying a parent with C<extends> will change the parent
363 Moose will also manage all attributes (including inherited ones) that are
364 defined with C<has>. And (assuming you call C<new>, which is inherited from
365 L<Moose::Object>) this includes properly initializing all instance slots,
366 setting defaults where appropriate, and performing any type constraint checking
369 =head1 PROVIDED METHODS
371 Moose provides a number of methods to all your classes, mostly through the
372 inheritance of L<Moose::Object>. There is however, one exception.
378 This is a method which provides access to the current class's metaclass.
382 =head1 EXPORTED FUNCTIONS
384 Moose will export a number of functions into the class's namespace which
385 may then be used to set up the class. These functions all work directly
386 on the current class.
390 =item B<extends (@superclasses)>
392 This function will set the superclass(es) for the current class.
394 This approach is recommended instead of C<use base>, because C<use base>
395 actually C<push>es onto the class's C<@ISA>, whereas C<extends> will
396 replace it. This is important to ensure that classes which do not have
397 superclasses still properly inherit from L<Moose::Object>.
399 Each superclass can be followed by a hash reference with options. Currently,
400 only L<-version|Class::MOP/Class Loading Options> is recognized:
402 extends 'My::Parent' => { -version => 0.01 },
403 'My::OtherParent' => { -version => 0.03 };
405 An exception will be thrown if the version requirements are not
408 =item B<with (@roles)>
410 This will apply a given set of C<@roles> to the local class.
412 Like with C<extends>, each specified role can be followed by a hash
413 reference with a L<-version|Class::MOP/Class Loading Options> option:
415 with 'My::Role' => { -version => 0.32 },
416 'My::Otherrole' => { -version => 0.23 };
418 The specified version requirements must be satisfied, otherwise an
419 exception will be thrown.
421 If your role takes options or arguments, they can be passed along in the
422 hash reference as well.
424 =item B<has $name|@$names =E<gt> %options>
426 This will install an attribute of a given C<$name> into the current class. If
427 the first parameter is an array reference, it will create an attribute for
428 every C<$name> in the list. The C<%options> will be passed to the constructor
429 for L<Moose::Meta::Attribute> (which inherits from L<Class::MOP::Attribute>),
430 so the full documentation for the valid options can be found there. These are
431 the most commonly used options:
435 =item I<is =E<gt> 'rw'|'ro'>
437 The I<is> option accepts either I<rw> (for read/write) or I<ro> (for read
438 only). These will create either a read/write accessor or a read-only
439 accessor respectively, using the same name as the C<$name> of the attribute.
441 If you need more control over how your accessors are named, you can
442 use the L<reader|Class::MOP::Attribute/reader>,
443 L<writer|Class::MOP::Attribute/writer> and
444 L<accessor|Class::MOP::Attribute/accessor> options inherited from
445 L<Class::MOP::Attribute>, however if you use those, you won't need the
448 =item I<isa =E<gt> $type_name>
450 The I<isa> option uses Moose's type constraint facilities to set up runtime
451 type checking for this attribute. Moose will perform the checks during class
452 construction, and within any accessors. The C<$type_name> argument must be a
453 string. The string may be either a class name or a type defined using
454 Moose's type definition features. (Refer to L<Moose::Util::TypeConstraints>
455 for information on how to define a new type, and how to retrieve type meta-data).
457 =item I<coerce =E<gt> (1|0)>
459 This will attempt to use coercion with the supplied type constraint to change
460 the value passed into any accessors or constructors. You B<must> supply a type
461 constraint, and that type constraint B<must> define a coercion. See
462 L<Moose::Cookbook::Basics::HTTP_SubtypesAndCoercion> for an example.
464 =item I<does =E<gt> $role_name>
466 This will accept the name of a role which the value stored in this attribute
467 is expected to have consumed.
469 =item I<required =E<gt> (1|0)>
471 This marks the attribute as being required. This means a value must be
472 supplied during class construction, I<or> the attribute must be lazy
473 and have either a default or a builder. Note that c<required> does not
474 say anything about the attribute's value, which can be C<undef>.
476 =item I<weak_ref =E<gt> (1|0)>
478 This will tell the class to store the value of this attribute as a weakened
479 reference. If an attribute is a weakened reference, it B<cannot> also be
480 coerced. Note that when a weak ref expires, the attribute's value becomes
481 undefined, and is still considered to be set for purposes of predicate,
484 =item I<lazy =E<gt> (1|0)>
486 This will tell the class to not create this slot until absolutely necessary.
487 If an attribute is marked as lazy it B<must> have a default or builder
490 =item I<trigger =E<gt> $code>
492 The I<trigger> option is a CODE reference which will be called after
493 the value of the attribute is set. The CODE ref is passed the
494 instance itself, the updated value, and the original value if the
495 attribute was already set.
497 You B<can> have a trigger on a read-only attribute.
499 B<NOTE:> Triggers will only fire when you B<assign> to the attribute,
500 either in the constructor, or using the writer. Default and built values will
501 B<not> cause the trigger to be fired.
503 =item I<handles =E<gt> ARRAY | HASH | REGEXP | ROLE | ROLETYPE | DUCKTYPE | CODE>
505 The I<handles> option provides Moose classes with automated delegation features.
506 This is a pretty complex and powerful option. It accepts many different option
507 formats, each with its own benefits and drawbacks.
509 B<NOTE:> The class being delegated to does not need to be a Moose based class,
510 which is why this feature is especially useful when wrapping non-Moose classes.
512 All I<handles> option formats share the following traits:
514 You cannot override a locally defined method with a delegated method; an
515 exception will be thrown if you try. That is to say, if you define C<foo> in
516 your class, you cannot override it with a delegated C<foo>. This is almost never
517 something you would want to do, and if it is, you should do it by hand and not
520 You cannot override any of the methods found in Moose::Object, or the C<BUILD>
521 and C<DEMOLISH> methods. These will not throw an exception, but will silently
522 move on to the next method in the list. My reasoning for this is that you would
523 almost never want to do this, since it usually breaks your class. As with
524 overriding locally defined methods, if you do want to do this, you should do it
525 manually, not with Moose.
527 You do not I<need> to have a reader (or accessor) for the attribute in order
528 to delegate to it. Moose will create a means of accessing the value for you,
529 however this will be several times B<less> efficient then if you had given
530 the attribute a reader (or accessor) to use.
532 Below is the documentation for each option format:
538 This is the most common usage for I<handles>. You basically pass a list of
539 method names to be delegated, and Moose will install a delegation method
544 This is the second most common usage for I<handles>. Instead of a list of
545 method names, you pass a HASH ref where each key is the method name you
546 want installed locally, and its value is the name of the original method
547 in the class being delegated to.
549 This can be very useful for recursive classes like trees. Here is a
550 quick example (soon to be expanded into a Moose::Cookbook recipe):
555 has 'node' => (is => 'rw', isa => 'Any');
560 default => sub { [] }
568 parent_node => 'node',
569 siblings => 'children',
573 In this example, the Tree package gets C<parent_node> and C<siblings> methods,
574 which delegate to the C<node> and C<children> methods (respectively) of the Tree
575 instance stored in the C<parent> slot.
577 You may also use an array reference to curry arguments to the original method.
581 handles => { set_foo => [ set => 'foo' ] },
584 # $self->set_foo(...) calls $self->thing->set('foo', ...)
586 The first element of the array reference is the original method name, and the
587 rest is a list of curried arguments.
591 The regexp option works very similar to the ARRAY option, except that it builds
592 the list of methods for you. It starts by collecting all possible methods of the
593 class being delegated to, then filters that list using the regexp supplied here.
595 B<NOTE:> An I<isa> option is required when using the regexp option format. This
596 is so that we can determine (at compile time) the method list from the class.
597 Without an I<isa> this is just not possible.
599 =item C<ROLE> or C<ROLETYPE>
601 With the role option, you specify the name of a role or a
602 L<role type|Moose::Meta::TypeConstraint::Role> whose "interface" then becomes
603 the list of methods to handle. The "interface" can be defined as; the methods
604 of the role and any required methods of the role. It should be noted that this
605 does B<not> include any method modifiers or generated attribute methods (which
606 is consistent with role composition).
610 With the duck type option, you pass a duck type object whose "interface" then
611 becomes the list of methods to handle. The "interface" can be defined as the
612 list of methods passed to C<duck_type> to create a duck type object. For more
613 information on C<duck_type> please check
614 L<Moose::Util::TypeConstraints>.
618 This is the option to use when you really want to do something funky. You should
619 only use it if you really know what you are doing, as it involves manual
622 This takes a code reference, which should expect two arguments. The first is the
623 attribute meta-object this I<handles> is attached to. The second is the
624 metaclass of the class being delegated to. It expects you to return a hash (not
625 a HASH ref) of the methods you want mapped.
629 =item I<traits =E<gt> [ @role_names ]>
631 This tells Moose to take the list of C<@role_names> and apply them to the
632 attribute meta-object. Custom attribute metaclass traits are useful for
633 extending the capabilities of the I<has> keyword: they are the simplest way to
634 extend the MOP, but they are still a fairly advanced topic and too much to
637 See L<Metaclass and Trait Name Resolution> for details on how a trait name is
638 resolved to a role name.
640 Also see L<Moose::Cookbook::Meta::Labeled_AttributeTrait> for a metaclass
643 =item I<builder> => Str
645 The value of this key is the name of the method that will be called to obtain
646 the value used to initialize the attribute. See the L<builder option docs in
647 Class::MOP::Attribute|Class::MOP::Attribute/builder> and/or
648 L<Moose::Cookbook::Basics::BinaryTree_BuilderAndLazyBuild> for more
651 =item I<default> => SCALAR | CODE
653 The value of this key is the default value which will initialize the attribute.
655 NOTE: If the value is a simple scalar (string or number), then it can
656 be just passed as is. However, if you wish to initialize it with a
657 HASH or ARRAY ref, then you need to wrap that inside a CODE reference.
658 See the L<default option docs in
659 Class::MOP::Attribute|Class::MOP::Attribute/default> for more
662 =item I<clearer> => Str
664 Creates a method allowing you to clear the value. See the L<clearer option
665 docs in Class::MOP::Attribute|Class::MOP::Attribute/clearer> for more
668 =item I<predicate> => Str
670 Creates a method to perform a basic test to see if a value has been set in the
671 attribute. See the L<predicate option docs in
672 Class::MOP::Attribute|Class::MOP::Attribute/predicate> for more information.
674 Note that the predicate will return true even for a C<weak_ref> attribute
675 whose value has expired.
677 =item I<documentation> => $string
679 An arbitrary string that can be retrieved later by calling C<<
680 $attr->documentation >>.
686 =item B<has +$name =E<gt> %options>
688 This is variation on the normal attribute creator C<has> which allows you to
689 clone and extend an attribute from a superclass or from a role. Here is an
690 example of the superclass usage:
698 default => 'Hello, I am a Foo'
706 has '+message' => (default => 'Hello I am My::Foo');
708 What is happening here is that B<My::Foo> is cloning the C<message> attribute
709 from its parent class B<Foo>, retaining the C<is =E<gt> 'rw'> and C<isa =E<gt>
710 'Str'> characteristics, but changing the value in C<default>.
712 Here is another example, but within the context of a role:
720 default => 'Hello, I am a Foo'
728 has '+message' => (default => 'Hello I am My::Foo');
730 In this case, we are basically taking the attribute which the role supplied
731 and altering it within the bounds of this feature.
733 Note that you can only extend an attribute from either a superclass or a role,
734 you cannot extend an attribute in a role that composes over an attribute from
737 Aside from where the attributes come from (one from superclass, the other
738 from a role), this feature works exactly the same. This feature is restricted
739 somewhat, so as to try and force at least I<some> sanity into it. Most options work the same, but there are some exceptions:
753 These options can be added, but cannot override a superclass definition.
757 You are allowed to B<add> additional traits to the C<traits> definition.
758 These traits will be composed into the attribute, but preexisting traits
759 B<are not> overridden, or removed.
763 =item B<before $name|@names|\@names|qr/.../ =E<gt> sub { ... }>
765 =item B<after $name|@names|\@names|qr/.../ =E<gt> sub { ... }>
767 =item B<around $name|@names|\@names|qr/.../ =E<gt> sub { ... }>
769 These three items are syntactic sugar for the before, after, and around method
770 modifier features that L<Class::MOP> provides. More information on these may be
771 found in L<Moose::Manual::MethodModifiers> and the
772 L<Class::MOP::Class documentation|Class::MOP::Class/"Method Modifiers">.
774 =item B<override ($name, &sub)>
776 An C<override> method is a way of explicitly saying "I am overriding this
777 method from my superclass". You can call C<super> within this method, and
778 it will work as expected. The same thing I<can> be accomplished with a normal
779 method call and the C<SUPER::> pseudo-package; it is really your choice.
783 The keyword C<super> is a no-op when called outside of an C<override> method. In
784 the context of an C<override> method, it will call the next most appropriate
785 superclass method with the same arguments as the original method.
787 =item B<augment ($name, &sub)>
789 An C<augment> method, is a way of explicitly saying "I am augmenting this
790 method from my superclass". Once again, the details of how C<inner> and
791 C<augment> work is best described in the
792 L<Moose::Cookbook::Basics::Document_AugmentAndInner>.
796 The keyword C<inner>, much like C<super>, is a no-op outside of the context of
797 an C<augment> method. You can think of C<inner> as being the inverse of
798 C<super>; the details of how C<inner> and C<augment> work is best described in
799 the L<Moose::Cookbook::Basics::Document_AugmentAndInner>.
803 This is the C<Scalar::Util::blessed> function. It is highly recommended that
804 this is used instead of C<ref> anywhere you need to test for an object's class
809 This is the C<Carp::confess> function, and exported here for historical
816 When you use Moose, you can specify traits which will be applied to your
819 use Moose -traits => 'My::Trait';
821 This is very similar to the attribute traits feature. When you do
822 this, your class's C<meta> object will have the specified traits
823 applied to it. See L<Metaclass and Trait Name Resolution> for more
826 =head2 Metaclass and Trait Name Resolution
828 By default, when given a trait name, Moose simply tries to load a
829 class of the same name. If such a class does not exist, it then looks
830 for for a class matching
831 B<Moose::Meta::$type::Custom::Trait::$trait_name>. The C<$type>
832 variable here will be one of B<Attribute> or B<Class>, depending on
833 what the trait is being applied to.
835 If a class with this long name exists, Moose checks to see if it has
836 the method C<register_implementation>. This method is expected to
837 return the I<real> class name of the trait. If there is no
838 C<register_implementation> method, it will fall back to using
839 B<Moose::Meta::$type::Custom::Trait::$trait> as the trait name.
841 The lookup method for metaclasses is the same, except that it looks
842 for a class matching B<Moose::Meta::$type::Custom::$metaclass_name>.
844 If all this is confusing, take a look at
845 L<Moose::Cookbook::Meta::Labeled_AttributeTrait>, which demonstrates how to
846 create an attribute trait.
848 =head1 UNIMPORTING FUNCTIONS
852 Moose offers a way to remove the keywords it exports, through the C<unimport>
853 method. You simply have to say C<no Moose> at the bottom of your code for this
854 to work. Here is an example:
859 has 'first_name' => (is => 'rw', isa => 'Str');
860 has 'last_name' => (is => 'rw', isa => 'Str');
864 $self->first_name . ' ' . $self->last_name
867 no Moose; # keywords are removed from the Person package
869 =head1 EXTENDING AND EMBEDDING MOOSE
871 To learn more about extending Moose, we recommend checking out the
872 "Extending" recipes in the L<Moose::Cookbook>, starting with
873 L<Moose::Cookbook::Extending::ExtensionOverview>, which provides an overview of
874 all the different ways you might extend Moose. L<Moose::Exporter> and
875 L<Moose::Util::MetaRole> are the modules which provide the majority of the
876 extension functionality, so reading their documentation should also be helpful.
878 =head2 The MooseX:: namespace
880 Generally if you're writing an extension I<for> Moose itself you'll want
881 to put your extension in the C<MooseX::> namespace. This namespace is
882 specifically for extensions that make Moose better or different in some
883 fundamental way. It is traditionally B<not> for a package that just happens
884 to use Moose. This namespace follows from the examples of the C<LWPx::>
885 and C<DBIx::> namespaces that perform the same function for C<LWP> and C<DBI>
888 =head1 METACLASS COMPATIBILITY AND MOOSE
890 Metaclass compatibility is a thorny subject. You should start by
891 reading the "About Metaclass compatibility" section in the
894 Moose will attempt to resolve a few cases of metaclass incompatibility
895 when you set the superclasses for a class, in addition to the cases that
896 C<Class::MOP> handles.
898 Moose tries to determine if the metaclasses only "differ by roles". This
899 means that the parent and child's metaclass share a common ancestor in
900 their respective hierarchies, and that the subclasses under the common
901 ancestor are only different because of role applications. This case is
902 actually fairly common when you mix and match various C<MooseX::*>
903 modules, many of which apply roles to the metaclass.
905 If the parent and child do differ by roles, Moose replaces the
906 metaclass in the child with a newly created metaclass. This metaclass
907 is a subclass of the parent's metaclass which does all of the roles that
908 the child's metaclass did before being replaced. Effectively, this
909 means the new metaclass does all of the roles done by both the
910 parent's and child's original metaclasses.
912 Ultimately, this is all transparent to you except in the case of an
913 unresolvable conflict.
921 It should be noted that C<super> and C<inner> B<cannot> be used in the same
922 method. However, they may be combined within the same class hierarchy; see
923 F<t/basics/override_augment_inner_super.t> for an example.
925 The reason for this is that C<super> is only valid within a method
926 with the C<override> modifier, and C<inner> will never be valid within an
927 C<override> method. In fact, C<augment> will skip over any C<override> methods
928 when searching for its appropriate C<inner>.
930 This might seem like a restriction, but I am of the opinion that keeping these
931 two features separate (yet interoperable) actually makes them easy to use, since
932 their behavior is then easier to predict. Time will tell whether I am right or
933 not (UPDATE: so far so good).
939 We offer both a mailing list and a very active IRC channel.
941 The mailing list is L<mailto:moose@perl.org>. You must be subscribed to send
942 a message. To subscribe, send an empty message to
943 L<mailto:moose-subscribe@perl.org>
945 You can also visit us at C<#moose> on L<irc://irc.perl.org/#moose>
946 This channel is quite active, and questions at all levels (on Moose-related
947 topics ;) are welcome.
949 =head1 ACKNOWLEDGEMENTS
953 =item I blame Sam Vilain for introducing me to the insanity that is meta-models.
955 =item I blame Audrey Tang for then encouraging my meta-model habit in #perl6.
957 =item Without Yuval "nothingmuch" Kogman this module would not be possible,
958 and it certainly wouldn't have this name ;P
960 =item The basis of the TypeContraints module was Rob Kinyon's idea
961 originally, I just ran with it.
963 =item Thanks to mst & chansen and the whole #moose posse for all the
964 early ideas/feature-requests/encouragement/bug-finding.
966 =item Thanks to David "Theory" Wheeler for meta-discussions and spelling fixes.
974 =item L<http://www.iinteractive.com/moose>
976 This is the official web home of Moose. It contains links to our public git
977 repository, as well as links to a number of talks and articles on Moose and
978 Moose related technologies.
980 =item the L<Moose manual|Moose::Manual>
982 This is an introduction to Moose which covers most of the basics.
984 =item Modern Perl, by chromatic
986 This is an introduction to modern Perl programming, which includes a section on
987 Moose. It is available in print and as a free download from
988 L<http://onyxneon.com/books/modern_perl/>.
990 =item The Moose is flying, a tutorial by Randal Schwartz
992 Part 1 - L<http://www.stonehenge.com/merlyn/LinuxMag/col94.html>
994 Part 2 - L<http://www.stonehenge.com/merlyn/LinuxMag/col95.html>
996 =item Several Moose extension modules in the C<MooseX::> namespace.
998 See L<http://search.cpan.org/search?query=MooseX::> for extensions.
1006 =item The Art of the MetaObject Protocol
1008 I mention this in the L<Class::MOP> docs too, as this book was critical in
1009 the development of both modules and is highly recommended.
1017 =item L<http://www.cs.utah.edu/plt/publications/oopsla04-gff.pdf>
1019 This paper (suggested by lbr on #moose) was what lead to the implementation
1020 of the C<super>/C<override> and C<inner>/C<augment> features. If you really
1021 want to understand them, I suggest you read this.
1027 All complex software has bugs lurking in it, and this module is no
1030 Please report any bugs to C<bug-moose@rt.cpan.org>, or through the web
1031 interface at L<http://rt.cpan.org>.
1033 You can also discuss feature requests or possible bugs on the Moose mailing
1034 list (moose@perl.org) or on IRC at L<irc://irc.perl.org/#moose>.
1036 =head1 FEATURE REQUESTS
1038 We are very strict about what features we add to the Moose core, especially
1039 the user-visible features. Instead we have made sure that the underlying
1040 meta-system of Moose is as extensible as possible so that you can add your
1041 own features easily.
1043 That said, occasionally there is a feature needed in the meta-system
1044 to support your planned extension, in which case you should either
1045 email the mailing list (moose@perl.org) or join us on IRC at
1046 L<irc://irc.perl.org/#moose> to discuss. The
1047 L<Moose::Manual::Contributing> has more detail about how and when you
1052 There are only a few people with the rights to release a new version
1053 of Moose. The Moose Cabal are the people to go to with questions regarding
1054 the wider purview of Moose. They help maintain not just the code
1055 but the community as well.
1057 Stevan (stevan) Little E<lt>stevan@iinteractive.comE<gt>
1059 Jesse (doy) Luehrs E<lt>doy at tozt dot netE<gt>
1061 Yuval (nothingmuch) Kogman
1063 Shawn (sartak) Moore E<lt>sartak@bestpractical.comE<gt>
1065 Hans Dieter (confound) Pearcey E<lt>hdp@pobox.comE<gt>
1067 Chris (perigrin) Prather
1069 Florian Ragwitz E<lt>rafl@debian.orgE<gt>
1071 Dave (autarch) Rolsky E<lt>autarch@urth.orgE<gt>
1075 Moose is a community project, and as such, involves the work of many, many
1076 members of the community beyond just the members in the cabal. In particular:
1078 Dave (autarch) Rolsky wrote most of the documentation in L<Moose::Manual>.
1080 John (jgoulah) Goulah wrote L<Moose::Cookbook::Snack::Keywords>.
1082 Jess (castaway) Robinson wrote L<Moose::Cookbook::Snack::Types>.
1084 Aran (bluefeet) Clary Deltac wrote
1085 L<Moose::Cookbook::Basics::Genome_OverloadingSubtypesAndCoercion>.
1087 Anders (Debolaz) Nor Berle contributed L<Test::Moose> and L<Moose::Util>.
1089 Also, the code in L<Moose::Meta::Attribute::Native> is based on code from the
1090 L<MooseX::AttributeHelpers> distribution, which had contributions from:
1092 Chris (perigrin) Prather
1098 Florian (rafl) Ragwitz
1106 Paul (frodwith) Driver
1112 Robert (phaylon) Sedlacek
1114 Shawn (Sartak) Moore
1122 Finally, these people also contributed various tests, bug fixes,
1123 documentation, and features to the Moose codebase:
1127 Adam (Alias) Kennedy
1129 Christian (chansen) Hansen
1133 Dylan Hardison (doc fixes)
1135 Eric (ewilhelm) Wilhelm
1139 Guillermo (groditi) Roditi
1145 Jonathan (jrockway) Rockway
1149 Nathan (kolibrie) Gray
1151 Paul (frodwith) Driver
1153 Piotr (dexter) Roszatycki
1157 Robert (phaylon) Sedlacek
1161 Sam (mugwump) Vilain
1163 Scott (konobi) McWhirter
1165 Shlomi (rindolf) Fish
1169 Wallace (wreis) Reis
1171 ... and many other #moose folks