7 use Scalar::Util 'blessed';
8 use Carp 'carp', 'confess';
9 use Class::Load 'is_class_loaded';
11 use Moose::Deprecated;
17 die "Class::MOP version $Moose::VERSION required--this is version $Class::MOP::VERSION"
18 if $Moose::VERSION && $Class::MOP::VERSION ne $Moose::VERSION;
21 use Moose::Meta::Class;
22 use Moose::Meta::TypeConstraint;
23 use Moose::Meta::TypeCoercion;
24 use Moose::Meta::Attribute;
25 use Moose::Meta::Instance;
29 use Moose::Meta::Role;
30 use Moose::Meta::Role::Composite;
31 use Moose::Meta::Role::Application;
32 use Moose::Meta::Role::Application::RoleSummation;
33 use Moose::Meta::Role::Application::ToClass;
34 use Moose::Meta::Role::Application::ToRole;
35 use Moose::Meta::Role::Application::ToInstance;
37 use Moose::Util::TypeConstraints;
40 use Moose::Meta::Attribute::Native;
51 Moose->throw_error("Must derive at least one class") unless @_;
53 # this checks the metaclass to make sure
54 # it is correct, sometimes it can get out
55 # of sync when the classes are being built
56 $meta->superclasses(@_);
60 Moose::Util::apply_all_roles(shift, @_);
67 Moose->throw_error('Usage: has \'name\' => ( key => value, ... )')
70 my %context = Moose::Util::_caller_info;
71 $context{context} = 'has declaration';
72 $context{type} = 'class';
73 my %options = ( definition_context => \%context, @_ );
74 my $attrs = ( ref($name) eq 'ARRAY' ) ? $name : [ ($name) ];
75 $meta->add_attribute( $_, %options ) for @$attrs;
79 Moose::Util::add_method_modifier(shift, 'before', \@_);
83 Moose::Util::add_method_modifier(shift, 'after', \@_);
87 Moose::Util::add_method_modifier(shift, 'around', \@_);
96 carp 'Arguments passed to super() are ignored';
99 # This check avoids a recursion loop - see
100 # t/bugs/super_recursion.t
101 return if defined $SUPER_PACKAGE && $SUPER_PACKAGE ne caller();
102 return unless $SUPER_BODY; $SUPER_BODY->(@SUPER_ARGS);
107 my ( $name, $method ) = @_;
108 $meta->add_override_method_modifier( $name => $method );
113 our ( %INNER_BODY, %INNER_ARGS );
115 if ( my $body = $INNER_BODY{$pkg} ) {
116 my @args = @{ $INNER_ARGS{$pkg} };
117 local $INNER_ARGS{$pkg};
118 local $INNER_BODY{$pkg};
119 return $body->(@args);
127 my ( $name, $method ) = @_;
128 $meta->add_augment_method_modifier( $name => $method );
131 Moose::Exporter->setup_import_methods(
133 qw( extends with has before after around override augment )
138 \&Scalar::Util::blessed,
146 my $class = $args{for_class}
147 or Moose->throw_error("Cannot call init_meta without specifying a for_class");
148 my $base_class = $args{base_class} || 'Moose::Object';
149 my $metaclass = $args{metaclass} || 'Moose::Meta::Class';
150 my $meta_name = exists $args{meta_name} ? $args{meta_name} : 'meta';
152 Moose->throw_error("The Metaclass $metaclass must be loaded. (Perhaps you forgot to 'use $metaclass'?)")
153 unless is_class_loaded($metaclass);
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::Constructor
245 Moose::Meta::Method::Destructor
246 Moose::Meta::Method::Overridden
247 Moose::Meta::Method::Augmented
250 Moose::Meta::Role::Attribute
251 Moose::Meta::Role::Method
252 Moose::Meta::Role::Method::Required
253 Moose::Meta::Role::Method::Conflicting
255 Moose::Meta::Role::Composite
257 Moose::Meta::Role::Application
258 Moose::Meta::Role::Application::RoleSummation
259 Moose::Meta::Role::Application::ToClass
260 Moose::Meta::Role::Application::ToRole
261 Moose::Meta::Role::Application::ToInstance
265 inline_constructor => 0,
266 constructor_name => undef,
267 # these are Class::MOP accessors, so they need inlining
268 inline_accessors => 1
269 ) for grep { $_->is_mutable }
272 Moose::Meta::Method::Accessor
273 Moose::Meta::Method::Delegation
274 Moose::Meta::Mixin::AttributeCore
279 # ABSTRACT: A postmodern object system for Perl 5
288 use Moose; # automatically turns on strict and warnings
290 has 'x' => (is => 'rw', isa => 'Int');
291 has 'y' => (is => 'rw', isa => 'Int');
304 has 'z' => (is => 'rw', isa => 'Int');
306 after 'clear' => sub {
313 Moose is an extension of the Perl 5 object system.
315 The main goal of Moose is to make Perl 5 Object Oriented programming
316 easier, more consistent, and less tedious. With Moose you can think
317 more about what you want to do and less about the mechanics of OOP.
319 Additionally, Moose is built on top of L<Class::MOP>, which is a
320 metaclass system for Perl 5. This means that Moose not only makes
321 building normal Perl 5 objects better, but it provides the power of
322 metaclass programming as well.
326 If you're new to Moose, the best place to start is the
327 L<Moose::Manual> docs, followed by the L<Moose::Cookbook>. The intro
328 will show you what Moose is, and how it makes Perl 5 OO better.
330 The cookbook recipes on Moose basics will get you up to speed with
331 many of Moose's features quickly. Once you have an idea of what Moose
332 can do, you can use the API documentation to get more detail on
333 features which interest you.
335 =head2 Moose Extensions
337 The C<MooseX::> namespace is the official place to find Moose extensions.
338 These extensions can be found on the CPAN. The easiest way to find them
339 is to search for them (L<http://search.cpan.org/search?query=MooseX::>),
340 or to examine L<Task::Moose> which aims to keep an up-to-date, easily
341 installable list of Moose extensions.
345 Much of the Moose documentation has been translated into other languages.
351 Japanese docs can be found at
352 L<http://perldoc.perlassociation.org/pod/Moose-Doc-JA/index.html>. The
353 source POD files can be found in GitHub:
354 L<http://github.com/jpa/Moose-Doc-JA>
358 =head1 BUILDING CLASSES WITH MOOSE
360 Moose makes every attempt to provide as much convenience as possible during
361 class construction/definition, but still stay out of your way if you want it
362 to. Here are a few items to note when building classes with Moose.
364 When you C<use Moose>, Moose will set the class's parent class to
365 L<Moose::Object>, I<unless> the class using Moose already has a parent
366 class. In addition, specifying a parent with C<extends> will change the parent
369 Moose will also manage all attributes (including inherited ones) that are
370 defined with C<has>. And (assuming you call C<new>, which is inherited from
371 L<Moose::Object>) this includes properly initializing all instance slots,
372 setting defaults where appropriate, and performing any type constraint checking
375 =head1 PROVIDED METHODS
377 Moose provides a number of methods to all your classes, mostly through the
378 inheritance of L<Moose::Object>. There is however, one exception.
384 This is a method which provides access to the current class's metaclass.
388 =head1 EXPORTED FUNCTIONS
390 Moose will export a number of functions into the class's namespace which
391 may then be used to set up the class. These functions all work directly
392 on the current class.
396 =item B<extends (@superclasses)>
398 This function will set the superclass(es) for the current class.
400 This approach is recommended instead of C<use base>, because C<use base>
401 actually C<push>es onto the class's C<@ISA>, whereas C<extends> will
402 replace it. This is important to ensure that classes which do not have
403 superclasses still properly inherit from L<Moose::Object>.
405 Each superclass can be followed by a hash reference with options. Currently,
406 only L<-version|Class::MOP/Class Loading Options> is recognized:
408 extends 'My::Parent' => { -version => 0.01 },
409 'My::OtherParent' => { -version => 0.03 };
411 An exception will be thrown if the version requirements are not
414 =item B<with (@roles)>
416 This will apply a given set of C<@roles> to the local class.
418 Like with C<extends>, each specified role can be followed by a hash
419 reference with a L<-version|Class::MOP/Class Loading Options> option:
421 with 'My::Role' => { -version => 0.32 },
422 'My::Otherrole' => { -version => 0.23 };
424 The specified version requirements must be satisfied, otherwise an
425 exception will be thrown.
427 If your role takes options or arguments, they can be passed along in the
428 hash reference as well.
430 =item B<has $name|@$names =E<gt> %options>
432 This will install an attribute of a given C<$name> into the current class. If
433 the first parameter is an array reference, it will create an attribute for
434 every C<$name> in the list. The C<%options> will be passed to the constructor
435 for L<Moose::Meta::Attribute> (which inherits from L<Class::MOP::Attribute>),
436 so the full documentation for the valid options can be found there. These are
437 the most commonly used options:
441 =item I<is =E<gt> 'rw'|'ro'>
443 The I<is> option accepts either I<rw> (for read/write) or I<ro> (for read
444 only). These will create either a read/write accessor or a read-only
445 accessor respectively, using the same name as the C<$name> of the attribute.
447 If you need more control over how your accessors are named, you can
448 use the L<reader|Class::MOP::Attribute/reader>,
449 L<writer|Class::MOP::Attribute/writer> and
450 L<accessor|Class::MOP::Attribute/accessor> options inherited from
451 L<Class::MOP::Attribute>, however if you use those, you won't need the
454 =item I<isa =E<gt> $type_name>
456 The I<isa> option uses Moose's type constraint facilities to set up runtime
457 type checking for this attribute. Moose will perform the checks during class
458 construction, and within any accessors. The C<$type_name> argument must be a
459 string. The string may be either a class name or a type defined using
460 Moose's type definition features. (Refer to L<Moose::Util::TypeConstraints>
461 for information on how to define a new type, and how to retrieve type meta-data).
463 =item I<coerce =E<gt> (1|0)>
465 This will attempt to use coercion with the supplied type constraint to change
466 the value passed into any accessors or constructors. You B<must> supply a type
467 constraint, and that type constraint B<must> define a coercion. See
468 L<Moose::Cookbook::Basics::HTTP_SubtypesAndCoercion> for an example.
470 =item I<does =E<gt> $role_name>
472 This will accept the name of a role which the value stored in this attribute
473 is expected to have consumed.
475 =item I<required =E<gt> (1|0)>
477 This marks the attribute as being required. This means a value must be
478 supplied during class construction, I<or> the attribute must be lazy
479 and have either a default or a builder. Note that c<required> does not
480 say anything about the attribute's value, which can be C<undef>.
482 =item I<weak_ref =E<gt> (1|0)>
484 This will tell the class to store the value of this attribute as a weakened
485 reference. If an attribute is a weakened reference, it B<cannot> also be
486 coerced. Note that when a weak ref expires, the attribute's value becomes
487 undefined, and is still considered to be set for purposes of predicate,
490 =item I<lazy =E<gt> (1|0)>
492 This will tell the class to not create this slot until absolutely necessary.
493 If an attribute is marked as lazy it B<must> have a default or builder
496 =item I<trigger =E<gt> $code>
498 The I<trigger> option is a CODE reference which will be called after
499 the value of the attribute is set. The CODE ref is passed the
500 instance itself, the updated value, and the original value if the
501 attribute was already set.
503 You B<can> have a trigger on a read-only attribute.
505 B<NOTE:> Triggers will only fire when you B<assign> to the attribute,
506 either in the constructor, or using the writer. Default and built values will
507 B<not> cause the trigger to be fired.
509 =item I<handles =E<gt> ARRAY | HASH | REGEXP | ROLE | ROLETYPE | DUCKTYPE | CODE>
511 The I<handles> option provides Moose classes with automated delegation features.
512 This is a pretty complex and powerful option. It accepts many different option
513 formats, each with its own benefits and drawbacks.
515 B<NOTE:> The class being delegated to does not need to be a Moose based class,
516 which is why this feature is especially useful when wrapping non-Moose classes.
518 All I<handles> option formats share the following traits:
520 You cannot override a locally defined method with a delegated method; an
521 exception will be thrown if you try. That is to say, if you define C<foo> in
522 your class, you cannot override it with a delegated C<foo>. This is almost never
523 something you would want to do, and if it is, you should do it by hand and not
526 You cannot override any of the methods found in Moose::Object, or the C<BUILD>
527 and C<DEMOLISH> methods. These will not throw an exception, but will silently
528 move on to the next method in the list. My reasoning for this is that you would
529 almost never want to do this, since it usually breaks your class. As with
530 overriding locally defined methods, if you do want to do this, you should do it
531 manually, not with Moose.
533 You do not I<need> to have a reader (or accessor) for the attribute in order
534 to delegate to it. Moose will create a means of accessing the value for you,
535 however this will be several times B<less> efficient then if you had given
536 the attribute a reader (or accessor) to use.
538 Below is the documentation for each option format:
544 This is the most common usage for I<handles>. You basically pass a list of
545 method names to be delegated, and Moose will install a delegation method
550 This is the second most common usage for I<handles>. Instead of a list of
551 method names, you pass a HASH ref where each key is the method name you
552 want installed locally, and its value is the name of the original method
553 in the class being delegated to.
555 This can be very useful for recursive classes like trees. Here is a
556 quick example (soon to be expanded into a Moose::Cookbook recipe):
561 has 'node' => (is => 'rw', isa => 'Any');
566 default => sub { [] }
574 parent_node => 'node',
575 siblings => 'children',
579 In this example, the Tree package gets C<parent_node> and C<siblings> methods,
580 which delegate to the C<node> and C<children> methods (respectively) of the Tree
581 instance stored in the C<parent> slot.
583 You may also use an array reference to curry arguments to the original method.
587 handles => { set_foo => [ set => 'foo' ] },
590 # $self->set_foo(...) calls $self->thing->set('foo', ...)
592 The first element of the array reference is the original method name, and the
593 rest is a list of curried arguments.
597 The regexp option works very similar to the ARRAY option, except that it builds
598 the list of methods for you. It starts by collecting all possible methods of the
599 class being delegated to, then filters that list using the regexp supplied here.
601 B<NOTE:> An I<isa> option is required when using the regexp option format. This
602 is so that we can determine (at compile time) the method list from the class.
603 Without an I<isa> this is just not possible.
605 =item C<ROLE> or C<ROLETYPE>
607 With the role option, you specify the name of a role or a
608 L<role type|Moose::Meta::TypeConstraint::Role> whose "interface" then becomes
609 the list of methods to handle. The "interface" can be defined as; the methods
610 of the role and any required methods of the role. It should be noted that this
611 does B<not> include any method modifiers or generated attribute methods (which
612 is consistent with role composition).
616 With the duck type option, you pass a duck type object whose "interface" then
617 becomes the list of methods to handle. The "interface" can be defined as the
618 list of methods passed to C<duck_type> to create a duck type object. For more
619 information on C<duck_type> please check
620 L<Moose::Util::TypeConstraints>.
624 This is the option to use when you really want to do something funky. You should
625 only use it if you really know what you are doing, as it involves manual
628 This takes a code reference, which should expect two arguments. The first is the
629 attribute meta-object this I<handles> is attached to. The second is the
630 metaclass of the class being delegated to. It expects you to return a hash (not
631 a HASH ref) of the methods you want mapped.
635 =item I<traits =E<gt> [ @role_names ]>
637 This tells Moose to take the list of C<@role_names> and apply them to the
638 attribute meta-object. Custom attribute metaclass traits are useful for
639 extending the capabilities of the I<has> keyword: they are the simplest way to
640 extend the MOP, but they are still a fairly advanced topic and too much to
643 See L<Metaclass and Trait Name Resolution> for details on how a trait name is
644 resolved to a role name.
646 Also see L<Moose::Cookbook::Meta::Labeled_AttributeTrait> for a metaclass
649 =item I<builder> => Str
651 The value of this key is the name of the method that will be called to obtain
652 the value used to initialize the attribute. See the L<builder option docs in
653 Class::MOP::Attribute|Class::MOP::Attribute/builder> and/or
654 L<Moose::Cookbook::Basics::BinaryTree_BuilderAndLazyBuild> for more
657 =item I<default> => SCALAR | CODE
659 The value of this key is the default value which will initialize the attribute.
661 NOTE: If the value is a simple scalar (string or number), then it can
662 be just passed as is. However, if you wish to initialize it with a
663 HASH or ARRAY ref, then you need to wrap that inside a CODE reference.
664 See the L<default option docs in
665 Class::MOP::Attribute|Class::MOP::Attribute/default> for more
668 =item I<clearer> => Str
670 Creates a method allowing you to clear the value. See the L<clearer option
671 docs in Class::MOP::Attribute|Class::MOP::Attribute/clearer> for more
674 =item I<predicate> => Str
676 Creates a method to perform a basic test to see if a value has been set in the
677 attribute. See the L<predicate option docs in
678 Class::MOP::Attribute|Class::MOP::Attribute/predicate> for more information.
680 Note that the predicate will return true even for a C<weak_ref> attribute
681 whose value has expired.
683 =item I<documentation> => $string
685 An arbitrary string that can be retrieved later by calling C<<
686 $attr->documentation >>.
692 =item B<has +$name =E<gt> %options>
694 This is variation on the normal attribute creator C<has> which allows you to
695 clone and extend an attribute from a superclass or from a role. Here is an
696 example of the superclass usage:
704 default => 'Hello, I am a Foo'
712 has '+message' => (default => 'Hello I am My::Foo');
714 What is happening here is that B<My::Foo> is cloning the C<message> attribute
715 from its parent class B<Foo>, retaining the C<is =E<gt> 'rw'> and C<isa =E<gt>
716 'Str'> characteristics, but changing the value in C<default>.
718 Here is another example, but within the context of a role:
726 default => 'Hello, I am a Foo'
734 has '+message' => (default => 'Hello I am My::Foo');
736 In this case, we are basically taking the attribute which the role supplied
737 and altering it within the bounds of this feature.
739 Note that you can only extend an attribute from either a superclass or a role,
740 you cannot extend an attribute in a role that composes over an attribute from
743 Aside from where the attributes come from (one from superclass, the other
744 from a role), this feature works exactly the same. This feature is restricted
745 somewhat, so as to try and force at least I<some> sanity into it. Most options work the same, but there are some exceptions:
759 These options can be added, but cannot override a superclass definition.
763 You are allowed to B<add> additional traits to the C<traits> definition.
764 These traits will be composed into the attribute, but preexisting traits
765 B<are not> overridden, or removed.
769 =item B<before $name|@names|\@names|qr/.../ =E<gt> sub { ... }>
771 =item B<after $name|@names|\@names|qr/.../ =E<gt> sub { ... }>
773 =item B<around $name|@names|\@names|qr/.../ =E<gt> sub { ... }>
775 These three items are syntactic sugar for the before, after, and around method
776 modifier features that L<Class::MOP> provides. More information on these may be
777 found in L<Moose::Manual::MethodModifiers> and the
778 L<Class::MOP::Class documentation|Class::MOP::Class/"Method Modifiers">.
780 =item B<override ($name, &sub)>
782 An C<override> method is a way of explicitly saying "I am overriding this
783 method from my superclass". You can call C<super> within this method, and
784 it will work as expected. The same thing I<can> be accomplished with a normal
785 method call and the C<SUPER::> pseudo-package; it is really your choice.
789 The keyword C<super> is a no-op when called outside of an C<override> method. In
790 the context of an C<override> method, it will call the next most appropriate
791 superclass method with the same arguments as the original method.
793 =item B<augment ($name, &sub)>
795 An C<augment> method, is a way of explicitly saying "I am augmenting this
796 method from my superclass". Once again, the details of how C<inner> and
797 C<augment> work is best described in the
798 L<Moose::Cookbook::Basics::Document_AugmentAndInner>.
802 The keyword C<inner>, much like C<super>, is a no-op outside of the context of
803 an C<augment> method. You can think of C<inner> as being the inverse of
804 C<super>; the details of how C<inner> and C<augment> work is best described in
805 the L<Moose::Cookbook::Basics::Document_AugmentAndInner>.
809 This is the C<Scalar::Util::blessed> function. It is highly recommended that
810 this is used instead of C<ref> anywhere you need to test for an object's class
815 This is the C<Carp::confess> function, and exported here for historical
822 When you use Moose, you can specify traits which will be applied to your
825 use Moose -traits => 'My::Trait';
827 This is very similar to the attribute traits feature. When you do
828 this, your class's C<meta> object will have the specified traits
829 applied to it. See L<Metaclass and Trait Name Resolution> for more
832 =head2 Metaclass and Trait Name Resolution
834 By default, when given a trait name, Moose simply tries to load a
835 class of the same name. If such a class does not exist, it then looks
836 for for a class matching
837 B<Moose::Meta::$type::Custom::Trait::$trait_name>. The C<$type>
838 variable here will be one of B<Attribute> or B<Class>, depending on
839 what the trait is being applied to.
841 If a class with this long name exists, Moose checks to see if it has
842 the method C<register_implementation>. This method is expected to
843 return the I<real> class name of the trait. If there is no
844 C<register_implementation> method, it will fall back to using
845 B<Moose::Meta::$type::Custom::Trait::$trait> as the trait name.
847 The lookup method for metaclasses is the same, except that it looks
848 for a class matching B<Moose::Meta::$type::Custom::$metaclass_name>.
850 If all this is confusing, take a look at
851 L<Moose::Cookbook::Meta::Labeled_AttributeTrait>, which demonstrates how to
852 create an attribute trait.
854 =head1 UNIMPORTING FUNCTIONS
858 Moose offers a way to remove the keywords it exports, through the C<unimport>
859 method. You simply have to say C<no Moose> at the bottom of your code for this
860 to work. Here is an example:
865 has 'first_name' => (is => 'rw', isa => 'Str');
866 has 'last_name' => (is => 'rw', isa => 'Str');
870 $self->first_name . ' ' . $self->last_name
873 no Moose; # keywords are removed from the Person package
875 =head1 EXTENDING AND EMBEDDING MOOSE
877 To learn more about extending Moose, we recommend checking out the
878 "Extending" recipes in the L<Moose::Cookbook>, starting with
879 L<Moose::Cookbook::Extending::ExtensionOverview>, which provides an overview of
880 all the different ways you might extend Moose. L<Moose::Exporter> and
881 L<Moose::Util::MetaRole> are the modules which provide the majority of the
882 extension functionality, so reading their documentation should also be helpful.
884 =head2 The MooseX:: namespace
886 Generally if you're writing an extension I<for> Moose itself you'll want
887 to put your extension in the C<MooseX::> namespace. This namespace is
888 specifically for extensions that make Moose better or different in some
889 fundamental way. It is traditionally B<not> for a package that just happens
890 to use Moose. This namespace follows from the examples of the C<LWPx::>
891 and C<DBIx::> namespaces that perform the same function for C<LWP> and C<DBI>
894 =head1 METACLASS COMPATIBILITY AND MOOSE
896 Metaclass compatibility is a thorny subject. You should start by
897 reading the "About Metaclass compatibility" section in the
900 Moose will attempt to resolve a few cases of metaclass incompatibility
901 when you set the superclasses for a class, in addition to the cases that
902 C<Class::MOP> handles.
904 Moose tries to determine if the metaclasses only "differ by roles". This
905 means that the parent and child's metaclass share a common ancestor in
906 their respective hierarchies, and that the subclasses under the common
907 ancestor are only different because of role applications. This case is
908 actually fairly common when you mix and match various C<MooseX::*>
909 modules, many of which apply roles to the metaclass.
911 If the parent and child do differ by roles, Moose replaces the
912 metaclass in the child with a newly created metaclass. This metaclass
913 is a subclass of the parent's metaclass which does all of the roles that
914 the child's metaclass did before being replaced. Effectively, this
915 means the new metaclass does all of the roles done by both the
916 parent's and child's original metaclasses.
918 Ultimately, this is all transparent to you except in the case of an
919 unresolvable conflict.
927 It should be noted that C<super> and C<inner> B<cannot> be used in the same
928 method. However, they may be combined within the same class hierarchy; see
929 F<t/basics/override_augment_inner_super.t> for an example.
931 The reason for this is that C<super> is only valid within a method
932 with the C<override> modifier, and C<inner> will never be valid within an
933 C<override> method. In fact, C<augment> will skip over any C<override> methods
934 when searching for its appropriate C<inner>.
936 This might seem like a restriction, but I am of the opinion that keeping these
937 two features separate (yet interoperable) actually makes them easy to use, since
938 their behavior is then easier to predict. Time will tell whether I am right or
939 not (UPDATE: so far so good).
945 We offer both a mailing list and a very active IRC channel.
947 The mailing list is L<mailto:moose@perl.org>. You must be subscribed to send
948 a message. To subscribe, send an empty message to
949 L<mailto:moose-subscribe@perl.org>
951 You can also visit us at C<#moose> on L<irc://irc.perl.org/#moose>
952 This channel is quite active, and questions at all levels (on Moose-related
953 topics ;) are welcome.
955 =head1 WHAT DOES MOOSE STAND FOR?
957 Moose doesn't stand for one thing in particular, however, if you want, here
958 are a few of our favorites. Feel free to contribute more!
962 =item * Make Other Object Systems Envious
964 =item * Makes Object Orientation So Easy
966 =item * Makes Object Orientation Spiffy- Er (sorry ingy)
968 =item * Most Other Object Systems Emasculate
970 =item * Moose Often Ovulate Sorta Early
972 =item * Moose Offers Often Super Extensions
974 =item * Meta Object Obligates Salivary Excitation
976 =item * Meta Object Orientation Syntax Extensions
980 =head1 ACKNOWLEDGEMENTS
984 =item I blame Sam Vilain for introducing me to the insanity that is meta-models.
986 =item I blame Audrey Tang for then encouraging my meta-model habit in #perl6.
988 =item Without Yuval "nothingmuch" Kogman this module would not be possible,
989 and it certainly wouldn't have this name ;P
991 =item The basis of the TypeContraints module was Rob Kinyon's idea
992 originally, I just ran with it.
994 =item Thanks to mst & chansen and the whole #moose posse for all the
995 early ideas/feature-requests/encouragement/bug-finding.
997 =item Thanks to David "Theory" Wheeler for meta-discussions and spelling fixes.
1005 =item L<http://www.iinteractive.com/moose>
1007 This is the official web home of Moose. It contains links to our public git
1008 repository, as well as links to a number of talks and articles on Moose and
1009 Moose related technologies.
1011 =item the L<Moose manual|Moose::Manual>
1013 This is an introduction to Moose which covers most of the basics.
1015 =item Modern Perl, by chromatic
1017 This is an introduction to modern Perl programming, which includes a section on
1018 Moose. It is available in print and as a free download from
1019 L<http://onyxneon.com/books/modern_perl/>.
1021 =item The Moose is flying, a tutorial by Randal Schwartz
1023 Part 1 - L<http://www.stonehenge.com/merlyn/LinuxMag/col94.html>
1025 Part 2 - L<http://www.stonehenge.com/merlyn/LinuxMag/col95.html>
1027 =item Several Moose extension modules in the C<MooseX::> namespace.
1029 See L<http://search.cpan.org/search?query=MooseX::> for extensions.
1037 =item The Art of the MetaObject Protocol
1039 I mention this in the L<Class::MOP> docs too, as this book was critical in
1040 the development of both modules and is highly recommended.
1048 =item L<http://www.cs.utah.edu/plt/publications/oopsla04-gff.pdf>
1050 This paper (suggested by lbr on #moose) was what lead to the implementation
1051 of the C<super>/C<override> and C<inner>/C<augment> features. If you really
1052 want to understand them, I suggest you read this.
1058 All complex software has bugs lurking in it, and this module is no
1061 Please report any bugs to C<bug-moose@rt.cpan.org>, or through the web
1062 interface at L<http://rt.cpan.org>.
1064 You can also discuss feature requests or possible bugs on the Moose mailing
1065 list (moose@perl.org) or on IRC at L<irc://irc.perl.org/#moose>.
1067 =head1 FEATURE REQUESTS
1069 We are very strict about what features we add to the Moose core, especially
1070 the user-visible features. Instead we have made sure that the underlying
1071 meta-system of Moose is as extensible as possible so that you can add your
1072 own features easily.
1074 That said, occasionally there is a feature needed in the meta-system
1075 to support your planned extension, in which case you should either
1076 email the mailing list (moose@perl.org) or join us on IRC at
1077 L<irc://irc.perl.org/#moose> to discuss. The
1078 L<Moose::Manual::Contributing> has more detail about how and when you
1083 There are only a few people with the rights to release a new version
1084 of Moose. The Moose Cabal are the people to go to with questions regarding
1085 the wider purview of Moose. They help maintain not just the code
1086 but the community as well.
1088 Stevan (stevan) Little E<lt>stevan@iinteractive.comE<gt>
1090 Jesse (doy) Luehrs E<lt>doy at tozt dot netE<gt>
1092 Yuval (nothingmuch) Kogman
1094 Shawn (sartak) Moore E<lt>sartak@bestpractical.comE<gt>
1096 Hans Dieter (confound) Pearcey E<lt>hdp@pobox.comE<gt>
1098 Chris (perigrin) Prather
1100 Florian Ragwitz E<lt>rafl@debian.orgE<gt>
1102 Dave (autarch) Rolsky E<lt>autarch@urth.orgE<gt>
1106 Moose is a community project, and as such, involves the work of many, many
1107 members of the community beyond just the members in the cabal. In particular:
1109 Dave (autarch) Rolsky wrote most of the documentation in L<Moose::Manual>.
1111 John (jgoulah) Goulah wrote L<Moose::Cookbook::Snack::Keywords>.
1113 Jess (castaway) Robinson wrote L<Moose::Cookbook::Snack::Types>.
1115 Aran (bluefeet) Clary Deltac wrote
1116 L<Moose::Cookbook::Basics::Genome_OverloadingSubtypesAndCoercion>.
1118 Anders (Debolaz) Nor Berle contributed L<Test::Moose> and L<Moose::Util>.
1120 Also, the code in L<Moose::Meta::Attribute::Native> is based on code from the
1121 L<MooseX::AttributeHelpers> distribution, which had contributions from:
1123 Chris (perigrin) Prather
1129 Florian (rafl) Ragwitz
1137 Paul (frodwith) Driver
1143 Robert (phaylon) Sedlacek
1145 Shawn (Sartak) Moore
1153 Finally, these people also contributed various tests, bug fixes,
1154 documentation, and features to the Moose codebase:
1158 Adam (Alias) Kennedy
1160 Christian (chansen) Hansen
1164 Dylan Hardison (doc fixes)
1166 Eric (ewilhelm) Wilhelm
1170 Guillermo (groditi) Roditi
1176 Jonathan (jrockway) Rockway
1180 Nathan (kolibrie) Gray
1182 Paul (frodwith) Driver
1184 Piotr (dexter) Roszatycki
1188 Robert (phaylon) Sedlacek
1192 Sam (mugwump) Vilain
1194 Scott (konobi) McWhirter
1196 Shlomi (rindolf) Fish
1200 Wallace (wreis) Reis
1202 ... and many other #moose folks