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;
54 $args{message} = shift;
60 my $roles = delete($args{roles});
62 my $metaclass = Moose::Meta::Class->create_anon_class(
63 superclasses => ['Throwable::Error'],
64 ($roles ? (roles => $roles) : ()),
67 $metaclass->name->throw(\%args);
73 Moose->throw_error("Must derive at least one class") unless @_;
75 # this checks the metaclass to make sure
76 # it is correct, sometimes it can get out
77 # of sync when the classes are being built
78 $meta->superclasses(@_);
82 Moose::Util::apply_all_roles(shift, @_);
89 Moose->throw_error('Usage: has \'name\' => ( key => value, ... )')
92 my %options = ( definition_context => Moose::Util::_caller_info(), @_ );
93 my $attrs = ( ref($name) eq 'ARRAY' ) ? $name : [ ($name) ];
94 $meta->add_attribute( $_, %options ) for @$attrs;
98 Moose::Util::add_method_modifier(shift, 'before', \@_);
102 Moose::Util::add_method_modifier(shift, 'after', \@_);
106 Moose::Util::add_method_modifier(shift, 'around', \@_);
114 # This check avoids a recursion loop - see
115 # t/bugs/super_recursion.t
116 return if defined $SUPER_PACKAGE && $SUPER_PACKAGE ne caller();
117 return unless $SUPER_BODY; $SUPER_BODY->(@SUPER_ARGS);
122 my ( $name, $method ) = @_;
123 $meta->add_override_method_modifier( $name => $method );
128 our ( %INNER_BODY, %INNER_ARGS );
130 if ( my $body = $INNER_BODY{$pkg} ) {
131 my @args = @{ $INNER_ARGS{$pkg} };
132 local $INNER_ARGS{$pkg};
133 local $INNER_BODY{$pkg};
134 return $body->(@args);
142 my ( $name, $method ) = @_;
143 $meta->add_augment_method_modifier( $name => $method );
146 Moose::Exporter->setup_import_methods(
148 qw( extends with has before after around override augment )
153 \&Scalar::Util::blessed,
161 my $class = $args{for_class}
162 or Moose->throw_error("Cannot call init_meta without specifying a for_class");
163 my $base_class = $args{base_class} || 'Moose::Object';
164 my $metaclass = $args{metaclass} || 'Moose::Meta::Class';
165 my $meta_name = exists $args{meta_name} ? $args{meta_name} : 'meta';
167 Moose->throw_error("The Metaclass $metaclass must be loaded. (Perhaps you forgot to 'use $metaclass'?)")
168 unless is_class_loaded($metaclass);
170 Moose->throw_error("The Metaclass $metaclass must be a subclass of Moose::Meta::Class.")
171 unless $metaclass->isa('Moose::Meta::Class');
173 # make a subtype for each Moose class
175 unless find_type_constraint($class);
179 if ( $meta = Class::MOP::get_metaclass_by_name($class) ) {
180 unless ( $meta->isa("Moose::Meta::Class") ) {
181 my $error_message = "$class already has a metaclass, but it does not inherit $metaclass ($meta).";
182 if ( $meta->isa('Moose::Meta::Role') ) {
183 Moose->throw_error($error_message . ' You cannot make the same thing a role and a class. Remove either Moose or Moose::Role.');
185 Moose->throw_error($error_message);
191 # now we check whether our ancestors have metaclass, and if so borrow that
192 my ( undef, @isa ) = @{ mro::get_linear_isa($class) };
194 foreach my $ancestor ( @isa ) {
195 my $ancestor_meta = Class::MOP::get_metaclass_by_name($ancestor) || next;
197 my $ancestor_meta_class = $ancestor_meta->_real_ref_name;
199 # if we have an ancestor metaclass that inherits $metaclass, we use
200 # that. This is like _fix_metaclass_incompatibility, but we can do it now.
202 # the case of having an ancestry is not very common, but arises in
204 unless ( $metaclass->isa( $ancestor_meta_class ) ) {
205 if ( $ancestor_meta_class->isa($metaclass) ) {
206 $metaclass = $ancestor_meta_class;
211 $meta = $metaclass->initialize($class);
214 if (defined $meta_name) {
215 # also check for inherited non moose 'meta' method?
216 my $existing = $meta->get_method($meta_name);
217 if ($existing && !$existing->isa('Class::MOP::Method::Meta')) {
218 Carp::cluck "Moose is overwriting an existing method named "
219 . "$meta_name in class $class with a method "
220 . "which returns the class's metaclass. If this is "
221 . "actually what you want, you should remove the "
222 . "existing method, otherwise, you should rename or "
223 . "disable this generated method using the "
224 . "'-meta_name' option to 'use Moose'.";
226 $meta->_add_meta_method($meta_name);
229 # make sure they inherit from Moose::Object
230 $meta->superclasses($base_class)
231 unless $meta->superclasses();
236 # This may be used in some older MooseX extensions.
238 goto &Moose::Exporter::_get_caller;
241 ## make 'em all immutable
244 inline_constructor => 1,
245 constructor_name => "_new",
246 # these are Class::MOP accessors, so they need inlining
247 inline_accessors => 1
248 ) for grep { $_->is_mutable }
251 Moose::Meta::Attribute
253 Moose::Meta::Instance
255 Moose::Meta::TypeCoercion
256 Moose::Meta::TypeCoercion::Union
259 Moose::Meta::Method::Constructor
260 Moose::Meta::Method::Destructor
261 Moose::Meta::Method::Overridden
262 Moose::Meta::Method::Augmented
265 Moose::Meta::Role::Attribute
266 Moose::Meta::Role::Method
267 Moose::Meta::Role::Method::Required
268 Moose::Meta::Role::Method::Conflicting
270 Moose::Meta::Role::Composite
272 Moose::Meta::Role::Application
273 Moose::Meta::Role::Application::RoleSummation
274 Moose::Meta::Role::Application::ToClass
275 Moose::Meta::Role::Application::ToRole
276 Moose::Meta::Role::Application::ToInstance
280 inline_constructor => 0,
281 constructor_name => undef,
282 # these are Class::MOP accessors, so they need inlining
283 inline_accessors => 1
284 ) for grep { $_->is_mutable }
287 Moose::Meta::Method::Accessor
288 Moose::Meta::Method::Delegation
289 Moose::Meta::Mixin::AttributeCore
294 # ABSTRACT: A postmodern object system for Perl 5
303 use Moose; # automatically turns on strict and warnings
305 has 'x' => (is => 'rw', isa => 'Int');
306 has 'y' => (is => 'rw', isa => 'Int');
319 has 'z' => (is => 'rw', isa => 'Int');
321 after 'clear' => sub {
328 Moose is an extension of the Perl 5 object system.
330 The main goal of Moose is to make Perl 5 Object Oriented programming
331 easier, more consistent, and less tedious. With Moose you can think
332 more about what you want to do and less about the mechanics of OOP.
334 Additionally, Moose is built on top of L<Class::MOP>, which is a
335 metaclass system for Perl 5. This means that Moose not only makes
336 building normal Perl 5 objects better, but it provides the power of
337 metaclass programming as well.
341 If you're new to Moose, the best place to start is the
342 L<Moose::Manual> docs, followed by the L<Moose::Cookbook>. The intro
343 will show you what Moose is, and how it makes Perl 5 OO better.
345 The cookbook recipes on Moose basics will get you up to speed with
346 many of Moose's features quickly. Once you have an idea of what Moose
347 can do, you can use the API documentation to get more detail on
348 features which interest you.
350 =head2 Moose Extensions
352 The C<MooseX::> namespace is the official place to find Moose extensions.
353 These extensions can be found on the CPAN. The easiest way to find them
354 is to search for them (L<http://search.cpan.org/search?query=MooseX::>),
355 or to examine L<Task::Moose> which aims to keep an up-to-date, easily
356 installable list of Moose extensions.
360 Much of the Moose documentation has been translated into other languages.
366 Japanese docs can be found at
367 L<http://perldoc.perlassociation.org/pod/Moose-Doc-JA/index.html>. The
368 source POD files can be found in GitHub:
369 L<http://github.com/jpa/Moose-Doc-JA>
373 =head1 BUILDING CLASSES WITH MOOSE
375 Moose makes every attempt to provide as much convenience as possible during
376 class construction/definition, but still stay out of your way if you want it
377 to. Here are a few items to note when building classes with Moose.
379 When you C<use Moose>, Moose will set the class's parent class to
380 L<Moose::Object>, I<unless> the class using Moose already has a parent
381 class. In addition, specifying a parent with C<extends> will change the parent
384 Moose will also manage all attributes (including inherited ones) that are
385 defined with C<has>. And (assuming you call C<new>, which is inherited from
386 L<Moose::Object>) this includes properly initializing all instance slots,
387 setting defaults where appropriate, and performing any type constraint checking
390 =head1 PROVIDED METHODS
392 Moose provides a number of methods to all your classes, mostly through the
393 inheritance of L<Moose::Object>. There is however, one exception.
399 This is a method which provides access to the current class's metaclass.
403 =head1 EXPORTED FUNCTIONS
405 Moose will export a number of functions into the class's namespace which
406 may then be used to set up the class. These functions all work directly
407 on the current class.
411 =item B<extends (@superclasses)>
413 This function will set the superclass(es) for the current class.
415 This approach is recommended instead of C<use base>, because C<use base>
416 actually C<push>es onto the class's C<@ISA>, whereas C<extends> will
417 replace it. This is important to ensure that classes which do not have
418 superclasses still properly inherit from L<Moose::Object>.
420 Each superclass can be followed by a hash reference with options. Currently,
421 only L<-version|Class::MOP/Class Loading Options> is recognized:
423 extends 'My::Parent' => { -version => 0.01 },
424 'My::OtherParent' => { -version => 0.03 };
426 An exception will be thrown if the version requirements are not
429 =item B<with (@roles)>
431 This will apply a given set of C<@roles> to the local class.
433 Like with C<extends>, each specified role can be followed by a hash
434 reference with a L<-version|Class::MOP/Class Loading Options> option:
436 with 'My::Role' => { -version => 0.32 },
437 'My::Otherrole' => { -version => 0.23 };
439 The specified version requirements must be satisfied, otherwise an
440 exception will be thrown.
442 If your role takes options or arguments, they can be passed along in the
443 hash reference as well.
445 =item B<has $name|@$names =E<gt> %options>
447 This will install an attribute of a given C<$name> into the current class. If
448 the first parameter is an array reference, it will create an attribute for
449 every C<$name> in the list. The C<%options> will be passed to the constructor
450 for L<Moose::Meta::Attribute> (which inherits from L<Class::MOP::Attribute>),
451 so the full documentation for the valid options can be found there. These are
452 the most commonly used options:
456 =item I<is =E<gt> 'rw'|'ro'>
458 The I<is> option accepts either I<rw> (for read/write) or I<ro> (for read
459 only). These will create either a read/write accessor or a read-only
460 accessor respectively, using the same name as the C<$name> of the attribute.
462 If you need more control over how your accessors are named, you can
463 use the L<reader|Class::MOP::Attribute/reader>,
464 L<writer|Class::MOP::Attribute/writer> and
465 L<accessor|Class::MOP::Attribute/accessor> options inherited from
466 L<Class::MOP::Attribute>, however if you use those, you won't need the
469 =item I<isa =E<gt> $type_name>
471 The I<isa> option uses Moose's type constraint facilities to set up runtime
472 type checking for this attribute. Moose will perform the checks during class
473 construction, and within any accessors. The C<$type_name> argument must be a
474 string. The string may be either a class name or a type defined using
475 Moose's type definition features. (Refer to L<Moose::Util::TypeConstraints>
476 for information on how to define a new type, and how to retrieve type meta-data).
478 =item I<coerce =E<gt> (1|0)>
480 This will attempt to use coercion with the supplied type constraint to change
481 the value passed into any accessors or constructors. You B<must> supply a type
482 constraint, and that type constraint B<must> define a coercion. See
483 L<Moose::Cookbook::Basics::HTTP_SubtypesAndCoercion> for an example.
485 =item I<does =E<gt> $role_name>
487 This will accept the name of a role which the value stored in this attribute
488 is expected to have consumed.
490 =item I<required =E<gt> (1|0)>
492 This marks the attribute as being required. This means a value must be
493 supplied during class construction, I<or> the attribute must be lazy
494 and have either a default or a builder. Note that c<required> does not
495 say anything about the attribute's value, which can be C<undef>.
497 =item I<weak_ref =E<gt> (1|0)>
499 This will tell the class to store the value of this attribute as a weakened
500 reference. If an attribute is a weakened reference, it B<cannot> also be
501 coerced. Note that when a weak ref expires, the attribute's value becomes
502 undefined, and is still considered to be set for purposes of predicate,
505 =item I<lazy =E<gt> (1|0)>
507 This will tell the class to not create this slot until absolutely necessary.
508 If an attribute is marked as lazy it B<must> have a default or builder
511 =item I<trigger =E<gt> $code>
513 The I<trigger> option is a CODE reference which will be called after
514 the value of the attribute is set. The CODE ref is passed the
515 instance itself, the updated value, and the original value if the
516 attribute was already set.
518 You B<can> have a trigger on a read-only attribute.
520 B<NOTE:> Triggers will only fire when you B<assign> to the attribute,
521 either in the constructor, or using the writer. Default and built values will
522 B<not> cause the trigger to be fired.
524 =item I<handles =E<gt> ARRAY | HASH | REGEXP | ROLE | ROLETYPE | DUCKTYPE | CODE>
526 The I<handles> option provides Moose classes with automated delegation features.
527 This is a pretty complex and powerful option. It accepts many different option
528 formats, each with its own benefits and drawbacks.
530 B<NOTE:> The class being delegated to does not need to be a Moose based class,
531 which is why this feature is especially useful when wrapping non-Moose classes.
533 All I<handles> option formats share the following traits:
535 You cannot override a locally defined method with a delegated method; an
536 exception will be thrown if you try. That is to say, if you define C<foo> in
537 your class, you cannot override it with a delegated C<foo>. This is almost never
538 something you would want to do, and if it is, you should do it by hand and not
541 You cannot override any of the methods found in Moose::Object, or the C<BUILD>
542 and C<DEMOLISH> methods. These will not throw an exception, but will silently
543 move on to the next method in the list. My reasoning for this is that you would
544 almost never want to do this, since it usually breaks your class. As with
545 overriding locally defined methods, if you do want to do this, you should do it
546 manually, not with Moose.
548 You do not I<need> to have a reader (or accessor) for the attribute in order
549 to delegate to it. Moose will create a means of accessing the value for you,
550 however this will be several times B<less> efficient then if you had given
551 the attribute a reader (or accessor) to use.
553 Below is the documentation for each option format:
559 This is the most common usage for I<handles>. You basically pass a list of
560 method names to be delegated, and Moose will install a delegation method
565 This is the second most common usage for I<handles>. Instead of a list of
566 method names, you pass a HASH ref where each key is the method name you
567 want installed locally, and its value is the name of the original method
568 in the class being delegated to.
570 This can be very useful for recursive classes like trees. Here is a
571 quick example (soon to be expanded into a Moose::Cookbook recipe):
576 has 'node' => (is => 'rw', isa => 'Any');
581 default => sub { [] }
589 parent_node => 'node',
590 siblings => 'children',
594 In this example, the Tree package gets C<parent_node> and C<siblings> methods,
595 which delegate to the C<node> and C<children> methods (respectively) of the Tree
596 instance stored in the C<parent> slot.
598 You may also use an array reference to curry arguments to the original method.
602 handles => { set_foo => [ set => 'foo' ] },
605 # $self->set_foo(...) calls $self->thing->set('foo', ...)
607 The first element of the array reference is the original method name, and the
608 rest is a list of curried arguments.
612 The regexp option works very similar to the ARRAY option, except that it builds
613 the list of methods for you. It starts by collecting all possible methods of the
614 class being delegated to, then filters that list using the regexp supplied here.
616 B<NOTE:> An I<isa> option is required when using the regexp option format. This
617 is so that we can determine (at compile time) the method list from the class.
618 Without an I<isa> this is just not possible.
620 =item C<ROLE> or C<ROLETYPE>
622 With the role option, you specify the name of a role or a
623 L<role type|Moose::Meta::TypeConstraint::Role> whose "interface" then becomes
624 the list of methods to handle. The "interface" can be defined as; the methods
625 of the role and any required methods of the role. It should be noted that this
626 does B<not> include any method modifiers or generated attribute methods (which
627 is consistent with role composition).
631 With the duck type option, you pass a duck type object whose "interface" then
632 becomes the list of methods to handle. The "interface" can be defined as the
633 list of methods passed to C<duck_type> to create a duck type object. For more
634 information on C<duck_type> please check
635 L<Moose::Util::TypeConstraints>.
639 This is the option to use when you really want to do something funky. You should
640 only use it if you really know what you are doing, as it involves manual
643 This takes a code reference, which should expect two arguments. The first is the
644 attribute meta-object this I<handles> is attached to. The second is the
645 metaclass of the class being delegated to. It expects you to return a hash (not
646 a HASH ref) of the methods you want mapped.
650 =item I<traits =E<gt> [ @role_names ]>
652 This tells Moose to take the list of C<@role_names> and apply them to the
653 attribute meta-object. Custom attribute metaclass traits are useful for
654 extending the capabilities of the I<has> keyword: they are the simplest way to
655 extend the MOP, but they are still a fairly advanced topic and too much to
658 See L<Metaclass and Trait Name Resolution> for details on how a trait name is
659 resolved to a role name.
661 Also see L<Moose::Cookbook::Meta::Labeled_AttributeTrait> for a metaclass
664 =item I<builder> => Str
666 The value of this key is the name of the method that will be called to obtain
667 the value used to initialize the attribute. See the L<builder option docs in
668 Class::MOP::Attribute|Class::MOP::Attribute/builder> and/or
669 L<Moose::Cookbook::Basics::BinaryTree_BuilderAndLazyBuild> for more
672 =item I<default> => SCALAR | CODE
674 The value of this key is the default value which will initialize the attribute.
676 NOTE: If the value is a simple scalar (string or number), then it can
677 be just passed as is. However, if you wish to initialize it with a
678 HASH or ARRAY ref, then you need to wrap that inside a CODE reference.
679 See the L<default option docs in
680 Class::MOP::Attribute|Class::MOP::Attribute/default> for more
683 =item I<clearer> => Str
685 Creates a method allowing you to clear the value. See the L<clearer option
686 docs in Class::MOP::Attribute|Class::MOP::Attribute/clearer> for more
689 =item I<predicate> => Str
691 Creates a method to perform a basic test to see if a value has been set in the
692 attribute. See the L<predicate option docs in
693 Class::MOP::Attribute|Class::MOP::Attribute/predicate> for more information.
695 Note that the predicate will return true even for a C<weak_ref> attribute
696 whose value has expired.
698 =item I<documentation> => $string
700 An arbitrary string that can be retrieved later by calling C<<
701 $attr->documentation >>.
707 =item B<has +$name =E<gt> %options>
709 This is variation on the normal attribute creator C<has> which allows you to
710 clone and extend an attribute from a superclass or from a role. Here is an
711 example of the superclass usage:
719 default => 'Hello, I am a Foo'
727 has '+message' => (default => 'Hello I am My::Foo');
729 What is happening here is that B<My::Foo> is cloning the C<message> attribute
730 from its parent class B<Foo>, retaining the C<is =E<gt> 'rw'> and C<isa =E<gt>
731 'Str'> characteristics, but changing the value in C<default>.
733 Here is another example, but within the context of a role:
741 default => 'Hello, I am a Foo'
749 has '+message' => (default => 'Hello I am My::Foo');
751 In this case, we are basically taking the attribute which the role supplied
752 and altering it within the bounds of this feature.
754 Note that you can only extend an attribute from either a superclass or a role,
755 you cannot extend an attribute in a role that composes over an attribute from
758 Aside from where the attributes come from (one from superclass, the other
759 from a role), this feature works exactly the same. This feature is restricted
760 somewhat, so as to try and force at least I<some> sanity into it. Most options work the same, but there are some exceptions:
774 These options can be added, but cannot override a superclass definition.
778 You are allowed to B<add> additional traits to the C<traits> definition.
779 These traits will be composed into the attribute, but preexisting traits
780 B<are not> overridden, or removed.
784 =item B<before $name|@names|\@names|qr/.../ =E<gt> sub { ... }>
786 =item B<after $name|@names|\@names|qr/.../ =E<gt> sub { ... }>
788 =item B<around $name|@names|\@names|qr/.../ =E<gt> sub { ... }>
790 These three items are syntactic sugar for the before, after, and around method
791 modifier features that L<Class::MOP> provides. More information on these may be
792 found in L<Moose::Manual::MethodModifiers> and the
793 L<Class::MOP::Class documentation|Class::MOP::Class/"Method Modifiers">.
795 =item B<override ($name, &sub)>
797 An C<override> method is a way of explicitly saying "I am overriding this
798 method from my superclass". You can call C<super> within this method, and
799 it will work as expected. The same thing I<can> be accomplished with a normal
800 method call and the C<SUPER::> pseudo-package; it is really your choice.
804 The keyword C<super> is a no-op when called outside of an C<override> method. In
805 the context of an C<override> method, it will call the next most appropriate
806 superclass method with the same arguments as the original method.
808 =item B<augment ($name, &sub)>
810 An C<augment> method, is a way of explicitly saying "I am augmenting this
811 method from my superclass". Once again, the details of how C<inner> and
812 C<augment> work is best described in the
813 L<Moose::Cookbook::Basics::Document_AugmentAndInner>.
817 The keyword C<inner>, much like C<super>, is a no-op outside of the context of
818 an C<augment> method. You can think of C<inner> as being the inverse of
819 C<super>; the details of how C<inner> and C<augment> work is best described in
820 the L<Moose::Cookbook::Basics::Document_AugmentAndInner>.
824 This is the C<Scalar::Util::blessed> function. It is highly recommended that
825 this is used instead of C<ref> anywhere you need to test for an object's class
830 This is the C<Carp::confess> function, and exported here for historical
837 When you use Moose, you can specify traits which will be applied to your
840 use Moose -traits => 'My::Trait';
842 This is very similar to the attribute traits feature. When you do
843 this, your class's C<meta> object will have the specified traits
844 applied to it. See L<Metaclass and Trait Name Resolution> for more
847 =head2 Metaclass and Trait Name Resolution
849 By default, when given a trait name, Moose simply tries to load a
850 class of the same name. If such a class does not exist, it then looks
851 for for a class matching
852 B<Moose::Meta::$type::Custom::Trait::$trait_name>. The C<$type>
853 variable here will be one of B<Attribute> or B<Class>, depending on
854 what the trait is being applied to.
856 If a class with this long name exists, Moose checks to see if it has
857 the method C<register_implementation>. This method is expected to
858 return the I<real> class name of the trait. If there is no
859 C<register_implementation> method, it will fall back to using
860 B<Moose::Meta::$type::Custom::Trait::$trait> as the trait name.
862 The lookup method for metaclasses is the same, except that it looks
863 for a class matching B<Moose::Meta::$type::Custom::$metaclass_name>.
865 If all this is confusing, take a look at
866 L<Moose::Cookbook::Meta::Labeled_AttributeTrait>, which demonstrates how to
867 create an attribute trait.
869 =head1 UNIMPORTING FUNCTIONS
873 Moose offers a way to remove the keywords it exports, through the C<unimport>
874 method. You simply have to say C<no Moose> at the bottom of your code for this
875 to work. Here is an example:
880 has 'first_name' => (is => 'rw', isa => 'Str');
881 has 'last_name' => (is => 'rw', isa => 'Str');
885 $self->first_name . ' ' . $self->last_name
888 no Moose; # keywords are removed from the Person package
890 =head1 EXTENDING AND EMBEDDING MOOSE
892 To learn more about extending Moose, we recommend checking out the
893 "Extending" recipes in the L<Moose::Cookbook>, starting with
894 L<Moose::Cookbook::Extending::ExtensionOverview>, which provides an overview of
895 all the different ways you might extend Moose. L<Moose::Exporter> and
896 L<Moose::Util::MetaRole> are the modules which provide the majority of the
897 extension functionality, so reading their documentation should also be helpful.
899 =head2 The MooseX:: namespace
901 Generally if you're writing an extension I<for> Moose itself you'll want
902 to put your extension in the C<MooseX::> namespace. This namespace is
903 specifically for extensions that make Moose better or different in some
904 fundamental way. It is traditionally B<not> for a package that just happens
905 to use Moose. This namespace follows from the examples of the C<LWPx::>
906 and C<DBIx::> namespaces that perform the same function for C<LWP> and C<DBI>
909 =head1 METACLASS COMPATIBILITY AND MOOSE
911 Metaclass compatibility is a thorny subject. You should start by
912 reading the "About Metaclass compatibility" section in the
915 Moose will attempt to resolve a few cases of metaclass incompatibility
916 when you set the superclasses for a class, in addition to the cases that
917 C<Class::MOP> handles.
919 Moose tries to determine if the metaclasses only "differ by roles". This
920 means that the parent and child's metaclass share a common ancestor in
921 their respective hierarchies, and that the subclasses under the common
922 ancestor are only different because of role applications. This case is
923 actually fairly common when you mix and match various C<MooseX::*>
924 modules, many of which apply roles to the metaclass.
926 If the parent and child do differ by roles, Moose replaces the
927 metaclass in the child with a newly created metaclass. This metaclass
928 is a subclass of the parent's metaclass which does all of the roles that
929 the child's metaclass did before being replaced. Effectively, this
930 means the new metaclass does all of the roles done by both the
931 parent's and child's original metaclasses.
933 Ultimately, this is all transparent to you except in the case of an
934 unresolvable conflict.
942 It should be noted that C<super> and C<inner> B<cannot> be used in the same
943 method. However, they may be combined within the same class hierarchy; see
944 F<t/basics/override_augment_inner_super.t> for an example.
946 The reason for this is that C<super> is only valid within a method
947 with the C<override> modifier, and C<inner> will never be valid within an
948 C<override> method. In fact, C<augment> will skip over any C<override> methods
949 when searching for its appropriate C<inner>.
951 This might seem like a restriction, but I am of the opinion that keeping these
952 two features separate (yet interoperable) actually makes them easy to use, since
953 their behavior is then easier to predict. Time will tell whether I am right or
954 not (UPDATE: so far so good).
960 We offer both a mailing list and a very active IRC channel.
962 The mailing list is L<mailto:moose@perl.org>. You must be subscribed to send
963 a message. To subscribe, send an empty message to
964 L<mailto:moose-subscribe@perl.org>
966 You can also visit us at C<#moose> on L<irc://irc.perl.org/#moose>
967 This channel is quite active, and questions at all levels (on Moose-related
968 topics ;) are welcome.
970 =head1 ACKNOWLEDGEMENTS
974 =item I blame Sam Vilain for introducing me to the insanity that is meta-models.
976 =item I blame Audrey Tang for then encouraging my meta-model habit in #perl6.
978 =item Without Yuval "nothingmuch" Kogman this module would not be possible,
979 and it certainly wouldn't have this name ;P
981 =item The basis of the TypeContraints module was Rob Kinyon's idea
982 originally, I just ran with it.
984 =item Thanks to mst & chansen and the whole #moose posse for all the
985 early ideas/feature-requests/encouragement/bug-finding.
987 =item Thanks to David "Theory" Wheeler for meta-discussions and spelling fixes.
995 =item L<http://www.iinteractive.com/moose>
997 This is the official web home of Moose. It contains links to our public git
998 repository, as well as links to a number of talks and articles on Moose and
999 Moose related technologies.
1001 =item the L<Moose manual|Moose::Manual>
1003 This is an introduction to Moose which covers most of the basics.
1005 =item Modern Perl, by chromatic
1007 This is an introduction to modern Perl programming, which includes a section on
1008 Moose. It is available in print and as a free download from
1009 L<http://onyxneon.com/books/modern_perl/>.
1011 =item The Moose is flying, a tutorial by Randal Schwartz
1013 Part 1 - L<http://www.stonehenge.com/merlyn/LinuxMag/col94.html>
1015 Part 2 - L<http://www.stonehenge.com/merlyn/LinuxMag/col95.html>
1017 =item Several Moose extension modules in the C<MooseX::> namespace.
1019 See L<http://search.cpan.org/search?query=MooseX::> for extensions.
1027 =item The Art of the MetaObject Protocol
1029 I mention this in the L<Class::MOP> docs too, as this book was critical in
1030 the development of both modules and is highly recommended.
1038 =item L<http://www.cs.utah.edu/plt/publications/oopsla04-gff.pdf>
1040 This paper (suggested by lbr on #moose) was what lead to the implementation
1041 of the C<super>/C<override> and C<inner>/C<augment> features. If you really
1042 want to understand them, I suggest you read this.
1048 All complex software has bugs lurking in it, and this module is no
1051 Please report any bugs to C<bug-moose@rt.cpan.org>, or through the web
1052 interface at L<http://rt.cpan.org>.
1054 You can also discuss feature requests or possible bugs on the Moose mailing
1055 list (moose@perl.org) or on IRC at L<irc://irc.perl.org/#moose>.
1057 =head1 FEATURE REQUESTS
1059 We are very strict about what features we add to the Moose core, especially
1060 the user-visible features. Instead we have made sure that the underlying
1061 meta-system of Moose is as extensible as possible so that you can add your
1062 own features easily.
1064 That said, occasionally there is a feature needed in the meta-system
1065 to support your planned extension, in which case you should either
1066 email the mailing list (moose@perl.org) or join us on IRC at
1067 L<irc://irc.perl.org/#moose> to discuss. The
1068 L<Moose::Manual::Contributing> has more detail about how and when you
1073 There are only a few people with the rights to release a new version
1074 of Moose. The Moose Cabal are the people to go to with questions regarding
1075 the wider purview of Moose. They help maintain not just the code
1076 but the community as well.
1078 Stevan (stevan) Little E<lt>stevan@iinteractive.comE<gt>
1080 Jesse (doy) Luehrs E<lt>doy at tozt dot netE<gt>
1082 Yuval (nothingmuch) Kogman
1084 Shawn (sartak) Moore E<lt>sartak@bestpractical.comE<gt>
1086 Hans Dieter (confound) Pearcey E<lt>hdp@pobox.comE<gt>
1088 Chris (perigrin) Prather
1090 Florian Ragwitz E<lt>rafl@debian.orgE<gt>
1092 Dave (autarch) Rolsky E<lt>autarch@urth.orgE<gt>
1096 Moose is a community project, and as such, involves the work of many, many
1097 members of the community beyond just the members in the cabal. In particular:
1099 Dave (autarch) Rolsky wrote most of the documentation in L<Moose::Manual>.
1101 John (jgoulah) Goulah wrote L<Moose::Cookbook::Snack::Keywords>.
1103 Jess (castaway) Robinson wrote L<Moose::Cookbook::Snack::Types>.
1105 Aran (bluefeet) Clary Deltac wrote
1106 L<Moose::Cookbook::Basics::Genome_OverloadingSubtypesAndCoercion>.
1108 Anders (Debolaz) Nor Berle contributed L<Test::Moose> and L<Moose::Util>.
1110 Also, the code in L<Moose::Meta::Attribute::Native> is based on code from the
1111 L<MooseX::AttributeHelpers> distribution, which had contributions from:
1113 Chris (perigrin) Prather
1119 Florian (rafl) Ragwitz
1127 Paul (frodwith) Driver
1133 Robert (phaylon) Sedlacek
1135 Shawn (Sartak) Moore
1143 Finally, these people also contributed various tests, bug fixes,
1144 documentation, and features to the Moose codebase:
1148 Adam (Alias) Kennedy
1150 Christian (chansen) Hansen
1154 Dylan Hardison (doc fixes)
1156 Eric (ewilhelm) Wilhelm
1160 Guillermo (groditi) Roditi
1166 Jonathan (jrockway) Rockway
1170 Nathan (kolibrie) Gray
1172 Paul (frodwith) Driver
1174 Piotr (dexter) Roszatycki
1178 Robert (phaylon) Sedlacek
1182 Sam (mugwump) Vilain
1184 Scott (konobi) McWhirter
1186 Shlomi (rindolf) Fish
1190 Wallace (wreis) Reis
1192 ... and many other #moose folks