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 %options = ( definition_context => Moose::Util::_caller_info(), @_ );
71 my $attrs = ( ref($name) eq 'ARRAY' ) ? $name : [ ($name) ];
72 $meta->add_attribute( $_, %options ) for @$attrs;
76 Moose::Util::add_method_modifier(shift, 'before', \@_);
80 Moose::Util::add_method_modifier(shift, 'after', \@_);
84 Moose::Util::add_method_modifier(shift, 'around', \@_);
93 carp 'Arguments passed to super() are ignored';
96 # This check avoids a recursion loop - see
97 # t/bugs/super_recursion.t
98 return if defined $SUPER_PACKAGE && $SUPER_PACKAGE ne caller();
99 return unless $SUPER_BODY; $SUPER_BODY->(@SUPER_ARGS);
104 my ( $name, $method ) = @_;
105 $meta->add_override_method_modifier( $name => $method );
110 our ( %INNER_BODY, %INNER_ARGS );
112 if ( my $body = $INNER_BODY{$pkg} ) {
113 my @args = @{ $INNER_ARGS{$pkg} };
114 local $INNER_ARGS{$pkg};
115 local $INNER_BODY{$pkg};
116 return $body->(@args);
124 my ( $name, $method ) = @_;
125 $meta->add_augment_method_modifier( $name => $method );
128 Moose::Exporter->setup_import_methods(
130 qw( extends with has before after around override augment )
135 \&Scalar::Util::blessed,
143 my $class = $args{for_class}
144 or Moose->throw_error("Cannot call init_meta without specifying a for_class");
145 my $base_class = $args{base_class} || 'Moose::Object';
146 my $metaclass = $args{metaclass} || 'Moose::Meta::Class';
147 my $meta_name = exists $args{meta_name} ? $args{meta_name} : 'meta';
149 Moose->throw_error("The Metaclass $metaclass must be loaded. (Perhaps you forgot to 'use $metaclass'?)")
150 unless is_class_loaded($metaclass);
152 Moose->throw_error("The Metaclass $metaclass must be a subclass of Moose::Meta::Class.")
153 unless $metaclass->isa('Moose::Meta::Class');
155 # make a subtype for each Moose class
157 unless find_type_constraint($class);
161 if ( $meta = Class::MOP::get_metaclass_by_name($class) ) {
162 unless ( $meta->isa("Moose::Meta::Class") ) {
163 my $error_message = "$class already has a metaclass, but it does not inherit $metaclass ($meta).";
164 if ( $meta->isa('Moose::Meta::Role') ) {
165 Moose->throw_error($error_message . ' You cannot make the same thing a role and a class. Remove either Moose or Moose::Role.');
167 Moose->throw_error($error_message);
173 # now we check whether our ancestors have metaclass, and if so borrow that
174 my ( undef, @isa ) = @{ mro::get_linear_isa($class) };
176 foreach my $ancestor ( @isa ) {
177 my $ancestor_meta = Class::MOP::get_metaclass_by_name($ancestor) || next;
179 my $ancestor_meta_class = $ancestor_meta->_real_ref_name;
181 # if we have an ancestor metaclass that inherits $metaclass, we use
182 # that. This is like _fix_metaclass_incompatibility, but we can do it now.
184 # the case of having an ancestry is not very common, but arises in
186 unless ( $metaclass->isa( $ancestor_meta_class ) ) {
187 if ( $ancestor_meta_class->isa($metaclass) ) {
188 $metaclass = $ancestor_meta_class;
193 $meta = $metaclass->initialize($class);
196 if (defined $meta_name) {
197 # also check for inherited non moose 'meta' method?
198 my $existing = $meta->get_method($meta_name);
199 if ($existing && !$existing->isa('Class::MOP::Method::Meta')) {
200 Carp::cluck "Moose is overwriting an existing method named "
201 . "$meta_name in class $class with a method "
202 . "which returns the class's metaclass. If this is "
203 . "actually what you want, you should remove the "
204 . "existing method, otherwise, you should rename or "
205 . "disable this generated method using the "
206 . "'-meta_name' option to 'use Moose'.";
208 $meta->_add_meta_method($meta_name);
211 # make sure they inherit from Moose::Object
212 $meta->superclasses($base_class)
213 unless $meta->superclasses();
218 # This may be used in some older MooseX extensions.
220 goto &Moose::Exporter::_get_caller;
223 ## make 'em all immutable
226 inline_constructor => 1,
227 constructor_name => "_new",
228 # these are Class::MOP accessors, so they need inlining
229 inline_accessors => 1
230 ) for grep { $_->is_mutable }
233 Moose::Meta::Attribute
235 Moose::Meta::Instance
237 Moose::Meta::TypeCoercion
238 Moose::Meta::TypeCoercion::Union
241 Moose::Meta::Method::Constructor
242 Moose::Meta::Method::Destructor
243 Moose::Meta::Method::Overridden
244 Moose::Meta::Method::Augmented
247 Moose::Meta::Role::Attribute
248 Moose::Meta::Role::Method
249 Moose::Meta::Role::Method::Required
250 Moose::Meta::Role::Method::Conflicting
252 Moose::Meta::Role::Composite
254 Moose::Meta::Role::Application
255 Moose::Meta::Role::Application::RoleSummation
256 Moose::Meta::Role::Application::ToClass
257 Moose::Meta::Role::Application::ToRole
258 Moose::Meta::Role::Application::ToInstance
262 inline_constructor => 0,
263 constructor_name => undef,
264 # these are Class::MOP accessors, so they need inlining
265 inline_accessors => 1
266 ) for grep { $_->is_mutable }
269 Moose::Meta::Method::Accessor
270 Moose::Meta::Method::Delegation
271 Moose::Meta::Mixin::AttributeCore
276 # ABSTRACT: A postmodern object system for Perl 5
285 use Moose; # automatically turns on strict and warnings
287 has 'x' => (is => 'rw', isa => 'Int');
288 has 'y' => (is => 'rw', isa => 'Int');
301 has 'z' => (is => 'rw', isa => 'Int');
303 after 'clear' => sub {
310 Moose is an extension of the Perl 5 object system.
312 The main goal of Moose is to make Perl 5 Object Oriented programming
313 easier, more consistent, and less tedious. With Moose you can think
314 more about what you want to do and less about the mechanics of OOP.
316 Additionally, Moose is built on top of L<Class::MOP>, which is a
317 metaclass system for Perl 5. This means that Moose not only makes
318 building normal Perl 5 objects better, but it provides the power of
319 metaclass programming as well.
323 If you're new to Moose, the best place to start is the
324 L<Moose::Manual> docs, followed by the L<Moose::Cookbook>. The intro
325 will show you what Moose is, and how it makes Perl 5 OO better.
327 The cookbook recipes on Moose basics will get you up to speed with
328 many of Moose's features quickly. Once you have an idea of what Moose
329 can do, you can use the API documentation to get more detail on
330 features which interest you.
332 =head2 Moose Extensions
334 The C<MooseX::> namespace is the official place to find Moose extensions.
335 These extensions can be found on the CPAN. The easiest way to find them
336 is to search for them (L<http://search.cpan.org/search?query=MooseX::>),
337 or to examine L<Task::Moose> which aims to keep an up-to-date, easily
338 installable list of Moose extensions.
342 Much of the Moose documentation has been translated into other languages.
348 Japanese docs can be found at
349 L<http://perldoc.perlassociation.org/pod/Moose-Doc-JA/index.html>. The
350 source POD files can be found in GitHub:
351 L<http://github.com/jpa/Moose-Doc-JA>
355 =head1 BUILDING CLASSES WITH MOOSE
357 Moose makes every attempt to provide as much convenience as possible during
358 class construction/definition, but still stay out of your way if you want it
359 to. Here are a few items to note when building classes with Moose.
361 When you C<use Moose>, Moose will set the class's parent class to
362 L<Moose::Object>, I<unless> the class using Moose already has a parent
363 class. In addition, specifying a parent with C<extends> will change the parent
366 Moose will also manage all attributes (including inherited ones) that are
367 defined with C<has>. And (assuming you call C<new>, which is inherited from
368 L<Moose::Object>) this includes properly initializing all instance slots,
369 setting defaults where appropriate, and performing any type constraint checking
372 =head1 PROVIDED METHODS
374 Moose provides a number of methods to all your classes, mostly through the
375 inheritance of L<Moose::Object>. There is however, one exception.
381 This is a method which provides access to the current class's metaclass.
385 =head1 EXPORTED FUNCTIONS
387 Moose will export a number of functions into the class's namespace which
388 may then be used to set up the class. These functions all work directly
389 on the current class.
393 =item B<extends (@superclasses)>
395 This function will set the superclass(es) for the current class.
397 This approach is recommended instead of C<use base>, because C<use base>
398 actually C<push>es onto the class's C<@ISA>, whereas C<extends> will
399 replace it. This is important to ensure that classes which do not have
400 superclasses still properly inherit from L<Moose::Object>.
402 Each superclass can be followed by a hash reference with options. Currently,
403 only L<-version|Class::MOP/Class Loading Options> is recognized:
405 extends 'My::Parent' => { -version => 0.01 },
406 'My::OtherParent' => { -version => 0.03 };
408 An exception will be thrown if the version requirements are not
411 =item B<with (@roles)>
413 This will apply a given set of C<@roles> to the local class.
415 Like with C<extends>, each specified role can be followed by a hash
416 reference with a L<-version|Class::MOP/Class Loading Options> option:
418 with 'My::Role' => { -version => 0.32 },
419 'My::Otherrole' => { -version => 0.23 };
421 The specified version requirements must be satisfied, otherwise an
422 exception will be thrown.
424 If your role takes options or arguments, they can be passed along in the
425 hash reference as well.
427 =item B<has $name|@$names =E<gt> %options>
429 This will install an attribute of a given C<$name> into the current class. If
430 the first parameter is an array reference, it will create an attribute for
431 every C<$name> in the list. The C<%options> will be passed to the constructor
432 for L<Moose::Meta::Attribute> (which inherits from L<Class::MOP::Attribute>),
433 so the full documentation for the valid options can be found there. These are
434 the most commonly used options:
438 =item I<is =E<gt> 'rw'|'ro'>
440 The I<is> option accepts either I<rw> (for read/write) or I<ro> (for read
441 only). These will create either a read/write accessor or a read-only
442 accessor respectively, using the same name as the C<$name> of the attribute.
444 If you need more control over how your accessors are named, you can
445 use the L<reader|Class::MOP::Attribute/reader>,
446 L<writer|Class::MOP::Attribute/writer> and
447 L<accessor|Class::MOP::Attribute/accessor> options inherited from
448 L<Class::MOP::Attribute>, however if you use those, you won't need the
451 =item I<isa =E<gt> $type_name>
453 The I<isa> option uses Moose's type constraint facilities to set up runtime
454 type checking for this attribute. Moose will perform the checks during class
455 construction, and within any accessors. The C<$type_name> argument must be a
456 string. The string may be either a class name or a type defined using
457 Moose's type definition features. (Refer to L<Moose::Util::TypeConstraints>
458 for information on how to define a new type, and how to retrieve type meta-data).
460 =item I<coerce =E<gt> (1|0)>
462 This will attempt to use coercion with the supplied type constraint to change
463 the value passed into any accessors or constructors. You B<must> supply a type
464 constraint, and that type constraint B<must> define a coercion. See
465 L<Moose::Cookbook::Basics::HTTP_SubtypesAndCoercion> for an example.
467 =item I<does =E<gt> $role_name>
469 This will accept the name of a role which the value stored in this attribute
470 is expected to have consumed.
472 =item I<required =E<gt> (1|0)>
474 This marks the attribute as being required. This means a value must be
475 supplied during class construction, I<or> the attribute must be lazy
476 and have either a default or a builder. Note that c<required> does not
477 say anything about the attribute's value, which can be C<undef>.
479 =item I<weak_ref =E<gt> (1|0)>
481 This will tell the class to store the value of this attribute as a weakened
482 reference. If an attribute is a weakened reference, it B<cannot> also be
483 coerced. Note that when a weak ref expires, the attribute's value becomes
484 undefined, and is still considered to be set for purposes of predicate,
487 =item I<lazy =E<gt> (1|0)>
489 This will tell the class to not create this slot until absolutely necessary.
490 If an attribute is marked as lazy it B<must> have a default or builder
493 =item I<trigger =E<gt> $code>
495 The I<trigger> option is a CODE reference which will be called after
496 the value of the attribute is set. The CODE ref is passed the
497 instance itself, the updated value, and the original value if the
498 attribute was already set.
500 You B<can> have a trigger on a read-only attribute.
502 B<NOTE:> Triggers will only fire when you B<assign> to the attribute,
503 either in the constructor, or using the writer. Default and built values will
504 B<not> cause the trigger to be fired.
506 =item I<handles =E<gt> ARRAY | HASH | REGEXP | ROLE | ROLETYPE | DUCKTYPE | CODE>
508 The I<handles> option provides Moose classes with automated delegation features.
509 This is a pretty complex and powerful option. It accepts many different option
510 formats, each with its own benefits and drawbacks.
512 B<NOTE:> The class being delegated to does not need to be a Moose based class,
513 which is why this feature is especially useful when wrapping non-Moose classes.
515 All I<handles> option formats share the following traits:
517 You cannot override a locally defined method with a delegated method; an
518 exception will be thrown if you try. That is to say, if you define C<foo> in
519 your class, you cannot override it with a delegated C<foo>. This is almost never
520 something you would want to do, and if it is, you should do it by hand and not
523 You cannot override any of the methods found in Moose::Object, or the C<BUILD>
524 and C<DEMOLISH> methods. These will not throw an exception, but will silently
525 move on to the next method in the list. My reasoning for this is that you would
526 almost never want to do this, since it usually breaks your class. As with
527 overriding locally defined methods, if you do want to do this, you should do it
528 manually, not with Moose.
530 You do not I<need> to have a reader (or accessor) for the attribute in order
531 to delegate to it. Moose will create a means of accessing the value for you,
532 however this will be several times B<less> efficient then if you had given
533 the attribute a reader (or accessor) to use.
535 Below is the documentation for each option format:
541 This is the most common usage for I<handles>. You basically pass a list of
542 method names to be delegated, and Moose will install a delegation method
547 This is the second most common usage for I<handles>. Instead of a list of
548 method names, you pass a HASH ref where each key is the method name you
549 want installed locally, and its value is the name of the original method
550 in the class being delegated to.
552 This can be very useful for recursive classes like trees. Here is a
553 quick example (soon to be expanded into a Moose::Cookbook recipe):
558 has 'node' => (is => 'rw', isa => 'Any');
563 default => sub { [] }
571 parent_node => 'node',
572 siblings => 'children',
576 In this example, the Tree package gets C<parent_node> and C<siblings> methods,
577 which delegate to the C<node> and C<children> methods (respectively) of the Tree
578 instance stored in the C<parent> slot.
580 You may also use an array reference to curry arguments to the original method.
584 handles => { set_foo => [ set => 'foo' ] },
587 # $self->set_foo(...) calls $self->thing->set('foo', ...)
589 The first element of the array reference is the original method name, and the
590 rest is a list of curried arguments.
594 The regexp option works very similar to the ARRAY option, except that it builds
595 the list of methods for you. It starts by collecting all possible methods of the
596 class being delegated to, then filters that list using the regexp supplied here.
598 B<NOTE:> An I<isa> option is required when using the regexp option format. This
599 is so that we can determine (at compile time) the method list from the class.
600 Without an I<isa> this is just not possible.
602 =item C<ROLE> or C<ROLETYPE>
604 With the role option, you specify the name of a role or a
605 L<role type|Moose::Meta::TypeConstraint::Role> whose "interface" then becomes
606 the list of methods to handle. The "interface" can be defined as; the methods
607 of the role and any required methods of the role. It should be noted that this
608 does B<not> include any method modifiers or generated attribute methods (which
609 is consistent with role composition).
613 With the duck type option, you pass a duck type object whose "interface" then
614 becomes the list of methods to handle. The "interface" can be defined as the
615 list of methods passed to C<duck_type> to create a duck type object. For more
616 information on C<duck_type> please check
617 L<Moose::Util::TypeConstraints>.
621 This is the option to use when you really want to do something funky. You should
622 only use it if you really know what you are doing, as it involves manual
625 This takes a code reference, which should expect two arguments. The first is the
626 attribute meta-object this I<handles> is attached to. The second is the
627 metaclass of the class being delegated to. It expects you to return a hash (not
628 a HASH ref) of the methods you want mapped.
632 =item I<traits =E<gt> [ @role_names ]>
634 This tells Moose to take the list of C<@role_names> and apply them to the
635 attribute meta-object. Custom attribute metaclass traits are useful for
636 extending the capabilities of the I<has> keyword: they are the simplest way to
637 extend the MOP, but they are still a fairly advanced topic and too much to
640 See L<Metaclass and Trait Name Resolution> for details on how a trait name is
641 resolved to a role name.
643 Also see L<Moose::Cookbook::Meta::Labeled_AttributeTrait> for a metaclass
646 =item I<builder> => Str
648 The value of this key is the name of the method that will be called to obtain
649 the value used to initialize the attribute. See the L<builder option docs in
650 Class::MOP::Attribute|Class::MOP::Attribute/builder> and/or
651 L<Moose::Cookbook::Basics::BinaryTree_BuilderAndLazyBuild> for more
654 =item I<default> => SCALAR | CODE
656 The value of this key is the default value which will initialize the attribute.
658 NOTE: If the value is a simple scalar (string or number), then it can
659 be just passed as is. However, if you wish to initialize it with a
660 HASH or ARRAY ref, then you need to wrap that inside a CODE reference.
661 See the L<default option docs in
662 Class::MOP::Attribute|Class::MOP::Attribute/default> for more
665 =item I<clearer> => Str
667 Creates a method allowing you to clear the value. See the L<clearer option
668 docs in Class::MOP::Attribute|Class::MOP::Attribute/clearer> for more
671 =item I<predicate> => Str
673 Creates a method to perform a basic test to see if a value has been set in the
674 attribute. See the L<predicate option docs in
675 Class::MOP::Attribute|Class::MOP::Attribute/predicate> for more information.
677 Note that the predicate will return true even for a C<weak_ref> attribute
678 whose value has expired.
680 =item I<documentation> => $string
682 An arbitrary string that can be retrieved later by calling C<<
683 $attr->documentation >>.
689 =item B<has +$name =E<gt> %options>
691 This is variation on the normal attribute creator C<has> which allows you to
692 clone and extend an attribute from a superclass or from a role. Here is an
693 example of the superclass usage:
701 default => 'Hello, I am a Foo'
709 has '+message' => (default => 'Hello I am My::Foo');
711 What is happening here is that B<My::Foo> is cloning the C<message> attribute
712 from its parent class B<Foo>, retaining the C<is =E<gt> 'rw'> and C<isa =E<gt>
713 'Str'> characteristics, but changing the value in C<default>.
715 Here is another example, but within the context of a role:
723 default => 'Hello, I am a Foo'
731 has '+message' => (default => 'Hello I am My::Foo');
733 In this case, we are basically taking the attribute which the role supplied
734 and altering it within the bounds of this feature.
736 Note that you can only extend an attribute from either a superclass or a role,
737 you cannot extend an attribute in a role that composes over an attribute from
740 Aside from where the attributes come from (one from superclass, the other
741 from a role), this feature works exactly the same. This feature is restricted
742 somewhat, so as to try and force at least I<some> sanity into it. Most options work the same, but there are some exceptions:
756 These options can be added, but cannot override a superclass definition.
760 You are allowed to B<add> additional traits to the C<traits> definition.
761 These traits will be composed into the attribute, but preexisting traits
762 B<are not> overridden, or removed.
766 =item B<before $name|@names|\@names|qr/.../ =E<gt> sub { ... }>
768 =item B<after $name|@names|\@names|qr/.../ =E<gt> sub { ... }>
770 =item B<around $name|@names|\@names|qr/.../ =E<gt> sub { ... }>
772 These three items are syntactic sugar for the before, after, and around method
773 modifier features that L<Class::MOP> provides. More information on these may be
774 found in L<Moose::Manual::MethodModifiers> and the
775 L<Class::MOP::Class documentation|Class::MOP::Class/"Method Modifiers">.
777 =item B<override ($name, &sub)>
779 An C<override> method is a way of explicitly saying "I am overriding this
780 method from my superclass". You can call C<super> within this method, and
781 it will work as expected. The same thing I<can> be accomplished with a normal
782 method call and the C<SUPER::> pseudo-package; it is really your choice.
786 The keyword C<super> is a no-op when called outside of an C<override> method. In
787 the context of an C<override> method, it will call the next most appropriate
788 superclass method with the same arguments as the original method.
790 =item B<augment ($name, &sub)>
792 An C<augment> method, is a way of explicitly saying "I am augmenting this
793 method from my superclass". Once again, the details of how C<inner> and
794 C<augment> work is best described in the
795 L<Moose::Cookbook::Basics::Document_AugmentAndInner>.
799 The keyword C<inner>, much like C<super>, is a no-op outside of the context of
800 an C<augment> method. You can think of C<inner> as being the inverse of
801 C<super>; the details of how C<inner> and C<augment> work is best described in
802 the L<Moose::Cookbook::Basics::Document_AugmentAndInner>.
806 This is the C<Scalar::Util::blessed> function. It is highly recommended that
807 this is used instead of C<ref> anywhere you need to test for an object's class
812 This is the C<Carp::confess> function, and exported here for historical
819 When you use Moose, you can specify traits which will be applied to your
822 use Moose -traits => 'My::Trait';
824 This is very similar to the attribute traits feature. When you do
825 this, your class's C<meta> object will have the specified traits
826 applied to it. See L<Metaclass and Trait Name Resolution> for more
829 =head2 Metaclass and Trait Name Resolution
831 By default, when given a trait name, Moose simply tries to load a
832 class of the same name. If such a class does not exist, it then looks
833 for for a class matching
834 B<Moose::Meta::$type::Custom::Trait::$trait_name>. The C<$type>
835 variable here will be one of B<Attribute> or B<Class>, depending on
836 what the trait is being applied to.
838 If a class with this long name exists, Moose checks to see if it has
839 the method C<register_implementation>. This method is expected to
840 return the I<real> class name of the trait. If there is no
841 C<register_implementation> method, it will fall back to using
842 B<Moose::Meta::$type::Custom::Trait::$trait> as the trait name.
844 The lookup method for metaclasses is the same, except that it looks
845 for a class matching B<Moose::Meta::$type::Custom::$metaclass_name>.
847 If all this is confusing, take a look at
848 L<Moose::Cookbook::Meta::Labeled_AttributeTrait>, which demonstrates how to
849 create an attribute trait.
851 =head1 UNIMPORTING FUNCTIONS
855 Moose offers a way to remove the keywords it exports, through the C<unimport>
856 method. You simply have to say C<no Moose> at the bottom of your code for this
857 to work. Here is an example:
862 has 'first_name' => (is => 'rw', isa => 'Str');
863 has 'last_name' => (is => 'rw', isa => 'Str');
867 $self->first_name . ' ' . $self->last_name
870 no Moose; # keywords are removed from the Person package
872 =head1 EXTENDING AND EMBEDDING MOOSE
874 To learn more about extending Moose, we recommend checking out the
875 "Extending" recipes in the L<Moose::Cookbook>, starting with
876 L<Moose::Cookbook::Extending::ExtensionOverview>, which provides an overview of
877 all the different ways you might extend Moose. L<Moose::Exporter> and
878 L<Moose::Util::MetaRole> are the modules which provide the majority of the
879 extension functionality, so reading their documentation should also be helpful.
881 =head2 The MooseX:: namespace
883 Generally if you're writing an extension I<for> Moose itself you'll want
884 to put your extension in the C<MooseX::> namespace. This namespace is
885 specifically for extensions that make Moose better or different in some
886 fundamental way. It is traditionally B<not> for a package that just happens
887 to use Moose. This namespace follows from the examples of the C<LWPx::>
888 and C<DBIx::> namespaces that perform the same function for C<LWP> and C<DBI>
891 =head1 METACLASS COMPATIBILITY AND MOOSE
893 Metaclass compatibility is a thorny subject. You should start by
894 reading the "About Metaclass compatibility" section in the
897 Moose will attempt to resolve a few cases of metaclass incompatibility
898 when you set the superclasses for a class, in addition to the cases that
899 C<Class::MOP> handles.
901 Moose tries to determine if the metaclasses only "differ by roles". This
902 means that the parent and child's metaclass share a common ancestor in
903 their respective hierarchies, and that the subclasses under the common
904 ancestor are only different because of role applications. This case is
905 actually fairly common when you mix and match various C<MooseX::*>
906 modules, many of which apply roles to the metaclass.
908 If the parent and child do differ by roles, Moose replaces the
909 metaclass in the child with a newly created metaclass. This metaclass
910 is a subclass of the parent's metaclass which does all of the roles that
911 the child's metaclass did before being replaced. Effectively, this
912 means the new metaclass does all of the roles done by both the
913 parent's and child's original metaclasses.
915 Ultimately, this is all transparent to you except in the case of an
916 unresolvable conflict.
924 It should be noted that C<super> and C<inner> B<cannot> be used in the same
925 method. However, they may be combined within the same class hierarchy; see
926 F<t/basics/override_augment_inner_super.t> for an example.
928 The reason for this is that C<super> is only valid within a method
929 with the C<override> modifier, and C<inner> will never be valid within an
930 C<override> method. In fact, C<augment> will skip over any C<override> methods
931 when searching for its appropriate C<inner>.
933 This might seem like a restriction, but I am of the opinion that keeping these
934 two features separate (yet interoperable) actually makes them easy to use, since
935 their behavior is then easier to predict. Time will tell whether I am right or
936 not (UPDATE: so far so good).
942 We offer both a mailing list and a very active IRC channel.
944 The mailing list is L<mailto:moose@perl.org>. You must be subscribed to send
945 a message. To subscribe, send an empty message to
946 L<mailto:moose-subscribe@perl.org>
948 You can also visit us at C<#moose> on L<irc://irc.perl.org/#moose>
949 This channel is quite active, and questions at all levels (on Moose-related
950 topics ;) are welcome.
952 =head1 ACKNOWLEDGEMENTS
956 =item I blame Sam Vilain for introducing me to the insanity that is meta-models.
958 =item I blame Audrey Tang for then encouraging my meta-model habit in #perl6.
960 =item Without Yuval "nothingmuch" Kogman this module would not be possible,
961 and it certainly wouldn't have this name ;P
963 =item The basis of the TypeContraints module was Rob Kinyon's idea
964 originally, I just ran with it.
966 =item Thanks to mst & chansen and the whole #moose posse for all the
967 early ideas/feature-requests/encouragement/bug-finding.
969 =item Thanks to David "Theory" Wheeler for meta-discussions and spelling fixes.
977 =item L<http://www.iinteractive.com/moose>
979 This is the official web home of Moose. It contains links to our public git
980 repository, as well as links to a number of talks and articles on Moose and
981 Moose related technologies.
983 =item the L<Moose manual|Moose::Manual>
985 This is an introduction to Moose which covers most of the basics.
987 =item Modern Perl, by chromatic
989 This is an introduction to modern Perl programming, which includes a section on
990 Moose. It is available in print and as a free download from
991 L<http://onyxneon.com/books/modern_perl/>.
993 =item The Moose is flying, a tutorial by Randal Schwartz
995 Part 1 - L<http://www.stonehenge.com/merlyn/LinuxMag/col94.html>
997 Part 2 - L<http://www.stonehenge.com/merlyn/LinuxMag/col95.html>
999 =item Several Moose extension modules in the C<MooseX::> namespace.
1001 See L<http://search.cpan.org/search?query=MooseX::> for extensions.
1009 =item The Art of the MetaObject Protocol
1011 I mention this in the L<Class::MOP> docs too, as this book was critical in
1012 the development of both modules and is highly recommended.
1020 =item L<http://www.cs.utah.edu/plt/publications/oopsla04-gff.pdf>
1022 This paper (suggested by lbr on #moose) was what lead to the implementation
1023 of the C<super>/C<override> and C<inner>/C<augment> features. If you really
1024 want to understand them, I suggest you read this.
1030 All complex software has bugs lurking in it, and this module is no
1033 Please report any bugs to C<bug-moose@rt.cpan.org>, or through the web
1034 interface at L<http://rt.cpan.org>.
1036 You can also discuss feature requests or possible bugs on the Moose mailing
1037 list (moose@perl.org) or on IRC at L<irc://irc.perl.org/#moose>.
1039 =head1 FEATURE REQUESTS
1041 We are very strict about what features we add to the Moose core, especially
1042 the user-visible features. Instead we have made sure that the underlying
1043 meta-system of Moose is as extensible as possible so that you can add your
1044 own features easily.
1046 That said, occasionally there is a feature needed in the meta-system
1047 to support your planned extension, in which case you should either
1048 email the mailing list (moose@perl.org) or join us on IRC at
1049 L<irc://irc.perl.org/#moose> to discuss. The
1050 L<Moose::Manual::Contributing> has more detail about how and when you
1055 There are only a few people with the rights to release a new version
1056 of Moose. The Moose Cabal are the people to go to with questions regarding
1057 the wider purview of Moose. They help maintain not just the code
1058 but the community as well.
1060 Stevan (stevan) Little E<lt>stevan@iinteractive.comE<gt>
1062 Jesse (doy) Luehrs E<lt>doy at tozt dot netE<gt>
1064 Yuval (nothingmuch) Kogman
1066 Shawn (sartak) Moore E<lt>sartak@bestpractical.comE<gt>
1068 Hans Dieter (confound) Pearcey E<lt>hdp@pobox.comE<gt>
1070 Chris (perigrin) Prather
1072 Florian Ragwitz E<lt>rafl@debian.orgE<gt>
1074 Dave (autarch) Rolsky E<lt>autarch@urth.orgE<gt>
1078 Moose is a community project, and as such, involves the work of many, many
1079 members of the community beyond just the members in the cabal. In particular:
1081 Dave (autarch) Rolsky wrote most of the documentation in L<Moose::Manual>.
1083 John (jgoulah) Goulah wrote L<Moose::Cookbook::Snack::Keywords>.
1085 Jess (castaway) Robinson wrote L<Moose::Cookbook::Snack::Types>.
1087 Aran (bluefeet) Clary Deltac wrote
1088 L<Moose::Cookbook::Basics::Genome_OverloadingSubtypesAndCoercion>.
1090 Anders (Debolaz) Nor Berle contributed L<Test::Moose> and L<Moose::Util>.
1092 Also, the code in L<Moose::Meta::Attribute::Native> is based on code from the
1093 L<MooseX::AttributeHelpers> distribution, which had contributions from:
1095 Chris (perigrin) Prather
1101 Florian (rafl) Ragwitz
1109 Paul (frodwith) Driver
1115 Robert (phaylon) Sedlacek
1117 Shawn (Sartak) Moore
1125 Finally, these people also contributed various tests, bug fixes,
1126 documentation, and features to the Moose codebase:
1130 Adam (Alias) Kennedy
1132 Christian (chansen) Hansen
1136 Dylan Hardison (doc fixes)
1138 Eric (ewilhelm) Wilhelm
1142 Guillermo (groditi) Roditi
1148 Jonathan (jrockway) Rockway
1152 Nathan (kolibrie) Gray
1154 Paul (frodwith) Driver
1156 Piotr (dexter) Roszatycki
1160 Robert (phaylon) Sedlacek
1164 Sam (mugwump) Vilain
1166 Scott (konobi) McWhirter
1168 Shlomi (rindolf) Fish
1172 Wallace (wreis) Reis
1174 ... and many other #moose folks