10 $VERSION = eval $VERSION;
11 our $AUTHORITY = 'cpan:STEVAN';
13 use Scalar::Util 'blessed';
20 use Moose::Meta::Class;
21 use Moose::Meta::TypeConstraint;
22 use Moose::Meta::TypeCoercion;
23 use Moose::Meta::Attribute;
24 use Moose::Meta::Instance;
28 use Moose::Meta::Role;
29 use Moose::Meta::Role::Composite;
30 use Moose::Meta::Role::Application;
31 use Moose::Meta::Role::Application::RoleSummation;
32 use Moose::Meta::Role::Application::ToClass;
33 use Moose::Meta::Role::Application::ToRole;
34 use Moose::Meta::Role::Application::ToInstance;
36 use Moose::Util::TypeConstraints;
40 my $level = @_ ? ($_[0] + 1) : 2;
42 @info{qw(package file line)} = caller($level);
55 Moose->throw_error("Must derive at least one class") unless @_;
58 foreach my $super (@supers) {
59 Class::MOP::load_class($super);
60 Moose->throw_error("You cannot inherit from a Moose Role ($super)")
61 if $super->can('meta') &&
62 blessed $super->meta &&
63 $super->meta->isa('Moose::Meta::Role')
68 # this checks the metaclass to make sure
69 # it is correct, sometimes it can get out
70 # of sync when the classes are being built
71 my $meta = Moose::Meta::Class->initialize($class);
72 $meta->superclasses(@supers);
77 Moose::Util::apply_all_roles(Class::MOP::Class->initialize($class), @_);
84 Moose->throw_error('Usage: has \'name\' => ( key => value, ... )')
87 my %options = ( definition_context => _caller_info(), @_ );
88 my $attrs = ( ref($name) eq 'ARRAY' ) ? $name : [ ($name) ];
89 Class::MOP::Class->initialize($class)->add_attribute( $_, %options ) for @$attrs;
94 Moose::Util::add_method_modifier($class, 'before', \@_);
99 Moose::Util::add_method_modifier($class, 'after', \@_);
104 Moose::Util::add_method_modifier($class, 'around', \@_);
112 # This check avoids a recursion loop - see
113 # t/100_bugs/020_super_recursion.t
114 return if defined $SUPER_PACKAGE && $SUPER_PACKAGE ne caller();
115 return unless $SUPER_BODY; $SUPER_BODY->(@SUPER_ARGS);
120 my ( $name, $method ) = @_;
121 Class::MOP::Class->initialize($class)->add_override_method_modifier( $name => $method );
126 our ( %INNER_BODY, %INNER_ARGS );
128 if ( my $body = $INNER_BODY{$pkg} ) {
129 my @args = @{ $INNER_ARGS{$pkg} };
130 local $INNER_ARGS{$pkg};
131 local $INNER_BODY{$pkg};
132 return $body->(@args);
140 my ( $name, $method ) = @_;
141 Class::MOP::Class->initialize($class)->add_augment_method_modifier( $name => $method );
144 Moose::Exporter->setup_import_methods(
146 qw( extends with has before after around override augment)
151 \&Scalar::Util::blessed,
156 # This used to be called as a function. This hack preserves
157 # backwards compatibility.
158 if ( $_[0] ne __PACKAGE__ ) {
159 return __PACKAGE__->init_meta(
169 my $class = $args{for_class}
170 or Moose->throw_error("Cannot call init_meta without specifying a for_class");
171 my $base_class = $args{base_class} || 'Moose::Object';
172 my $metaclass = $args{metaclass} || 'Moose::Meta::Class';
174 Moose->throw_error("The Metaclass $metaclass must be a subclass of Moose::Meta::Class.")
175 unless $metaclass->isa('Moose::Meta::Class');
177 # make a subtype for each Moose class
179 unless find_type_constraint($class);
183 if ( $meta = Class::MOP::get_metaclass_by_name($class) ) {
184 unless ( $meta->isa("Moose::Meta::Class") ) {
185 Moose->throw_error("$class already has a metaclass, but it does not inherit $metaclass ($meta)");
188 # no metaclass, no 'meta' method
190 # now we check whether our ancestors have metaclass, and if so borrow that
191 my ( undef, @isa ) = @{ $class->mro::get_linear_isa };
193 foreach my $ancestor ( @isa ) {
194 my $ancestor_meta = Class::MOP::get_metaclass_by_name($ancestor) || next;
196 my $ancestor_meta_class = ($ancestor_meta->is_immutable
197 ? $ancestor_meta->get_mutable_metaclass_name
198 : ref($ancestor_meta));
200 # if we have an ancestor metaclass that inherits $metaclass, we use
201 # that. This is like _fix_metaclass_incompatibility, but we can do it now.
203 # the case of having an ancestry is not very common, but arises in
205 unless ( $metaclass->isa( $ancestor_meta_class ) ) {
206 if ( $ancestor_meta_class->isa($metaclass) ) {
207 $metaclass = $ancestor_meta_class;
212 $meta = $metaclass->initialize($class);
215 if ( $class->can('meta') ) {
216 # check 'meta' method
218 # it may be inherited
221 # this is the case where the metaclass pragma
222 # was used before the 'use Moose' statement to
223 # override a specific class
224 my $method_meta = $class->meta;
226 ( blessed($method_meta) && $method_meta->isa('Moose::Meta::Class') )
227 || Moose->throw_error("$class already has a &meta function, but it does not return a Moose::Meta::Class ($meta)");
229 $meta = $method_meta;
232 unless ( $meta->has_method("meta") ) { # don't overwrite
233 # also check for inherited non moose 'meta' method?
234 # FIXME also skip this if the user requested by passing an option
237 # re-initialize so it inherits properly
238 $metaclass->initialize( ref($_[0]) || $_[0] );
243 # make sure they inherit from Moose::Object
244 $meta->superclasses($base_class)
245 unless $meta->superclasses();
250 # This may be used in some older MooseX extensions.
252 goto &Moose::Exporter::_get_caller;
255 ## make 'em all immutable
258 inline_constructor => 1,
259 constructor_name => "_new",
260 # these are Class::MOP accessors, so they need inlining
261 inline_accessors => 1
262 ) for grep { $_->is_mutable }
265 Moose::Meta::Attribute
267 Moose::Meta::Instance
269 Moose::Meta::TypeCoercion
270 Moose::Meta::TypeCoercion::Union
273 Moose::Meta::Method::Accessor
274 Moose::Meta::Method::Constructor
275 Moose::Meta::Method::Destructor
276 Moose::Meta::Method::Overridden
277 Moose::Meta::Method::Augmented
280 Moose::Meta::Role::Method
281 Moose::Meta::Role::Method::Required
283 Moose::Meta::Role::Composite
285 Moose::Meta::Role::Application
286 Moose::Meta::Role::Application::RoleSummation
287 Moose::Meta::Role::Application::ToClass
288 Moose::Meta::Role::Application::ToRole
289 Moose::Meta::Role::Application::ToInstance
300 Moose - A postmodern object system for Perl 5
305 use Moose; # automatically turns on strict and warnings
307 has 'x' => (is => 'rw', isa => 'Int');
308 has 'y' => (is => 'rw', isa => 'Int');
321 has 'z' => (is => 'rw', isa => 'Int');
323 after 'clear' => sub {
330 Moose is an extension of the Perl 5 object system.
332 The main goal of Moose is to make Perl 5 Object Oriented programming
333 easier, more consistent and less tedious. With Moose you can to think
334 more about what you want to do and less about the mechanics of OOP.
336 Additionally, Moose is built on top of L<Class::MOP>, which is a
337 metaclass system for Perl 5. This means that Moose not only makes
338 building normal Perl 5 objects better, but it provides the power of
339 metaclass programming as well.
343 If you're new to Moose, the best place to start is the L<Moose::Intro>
344 docs, followed by the L<Moose::Cookbook>. The intro will show you what
345 Moose is, and how it makes Perl 5 OO better.
347 The cookbook recipes on Moose basics will get you up to speed with
348 many of Moose's features quickly. Once you have an idea of what Moose
349 can do, you can use the API documentation to get more detail on
350 features which interest you.
352 =head2 Moose Extensions
354 The C<MooseX::> namespace is the official place to find Moose extensions.
355 These extensions can be found on the CPAN. The easiest way to find them
356 is to search for them (L<http://search.cpan.org/search?query=MooseX::>),
357 or to examine L<Task::Moose> which aims to keep an up-to-date, easily
358 installable list of Moose extensions.
360 =head1 BUILDING CLASSES WITH MOOSE
362 Moose makes every attempt to provide as much convenience as possible during
363 class construction/definition, but still stay out of your way if you want it
364 to. Here are a few items to note when building classes with Moose.
366 Unless specified with C<extends>, any class which uses Moose will
367 inherit from L<Moose::Object>.
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 =item B<with (@roles)>
407 This will apply a given set of C<@roles> to the local class.
409 =item B<has $name|@$names =E<gt> %options>
411 This will install an attribute of a given C<$name> into the current class. If
412 the first parameter is an array reference, it will create an attribute for
413 every C<$name> in the list. The C<%options> are the same as those provided by
414 L<Class::MOP::Attribute>, in addition to the list below which are provided by
415 Moose (L<Moose::Meta::Attribute> to be more specific):
419 =item I<is =E<gt> 'rw'|'ro'>
421 The I<is> option accepts either I<rw> (for read/write) or I<ro> (for read
422 only). These will create either a read/write accessor or a read-only
423 accessor respectively, using the same name as the C<$name> of the attribute.
425 If you need more control over how your accessors are named, you can
426 use the L<reader|Class::MOP::Attribute/reader>,
427 L<writer|Class::MOP::Attribute/writer> and
428 L<accessor|Class::MOP::Attribute/accessor> options inherited from
429 L<Class::MOP::Attribute>, however if you use those, you won't need the
432 =item I<isa =E<gt> $type_name>
434 The I<isa> option uses Moose's type constraint facilities to set up runtime
435 type checking for this attribute. Moose will perform the checks during class
436 construction, and within any accessors. The C<$type_name> argument must be a
437 string. The string may be either a class name or a type defined using
438 Moose's type definition features. (Refer to L<Moose::Util::TypeConstraints>
439 for information on how to define a new type, and how to retrieve type meta-data).
441 =item I<coerce =E<gt> (1|0)>
443 This will attempt to use coercion with the supplied type constraint to change
444 the value passed into any accessors or constructors. You B<must> have supplied
445 a type constraint in order for this to work. See L<Moose::Cookbook::Basics::Recipe5>
448 =item I<does =E<gt> $role_name>
450 This will accept the name of a role which the value stored in this attribute
451 is expected to have consumed.
453 =item I<required =E<gt> (1|0)>
455 This marks the attribute as being required. This means a I<defined> value must be
456 supplied during class construction, and the attribute may never be set to
457 C<undef> with an accessor.
459 =item I<weak_ref =E<gt> (1|0)>
461 This will tell the class to store the value of this attribute as a weakened
462 reference. If an attribute is a weakened reference, it B<cannot> also be
465 =item I<lazy =E<gt> (1|0)>
467 This will tell the class to not create this slot until absolutely necessary.
468 If an attribute is marked as lazy it B<must> have a default supplied.
470 =item I<auto_deref =E<gt> (1|0)>
472 This tells the accessor whether to automatically dereference the value returned.
473 This is only legal if your C<isa> option is either C<ArrayRef> or C<HashRef>.
475 =item I<trigger =E<gt> $code>
477 The I<trigger> option is a CODE reference which will be called after the value of
478 the attribute is set. The CODE ref will be passed the instance itself, the
479 updated value and the attribute meta-object (this is for more advanced fiddling
480 and can typically be ignored). You B<cannot> have a trigger on a read-only
483 B<NOTE:> Triggers will only fire when you B<assign> to the attribute,
484 either in the constructor, or using the writer. Default and built values will
485 B<not> cause the trigger to be fired.
487 =item I<handles =E<gt> ARRAY | HASH | REGEXP | ROLE | CODE>
489 The I<handles> option provides Moose classes with automated delegation features.
490 This is a pretty complex and powerful option. It accepts many different option
491 formats, each with its own benefits and drawbacks.
493 B<NOTE:> The class being delegated to does not need to be a Moose based class,
494 which is why this feature is especially useful when wrapping non-Moose classes.
496 All I<handles> option formats share the following traits:
498 You cannot override a locally defined method with a delegated method; an
499 exception will be thrown if you try. That is to say, if you define C<foo> in
500 your class, you cannot override it with a delegated C<foo>. This is almost never
501 something you would want to do, and if it is, you should do it by hand and not
504 You cannot override any of the methods found in Moose::Object, or the C<BUILD>
505 and C<DEMOLISH> methods. These will not throw an exception, but will silently
506 move on to the next method in the list. My reasoning for this is that you would
507 almost never want to do this, since it usually breaks your class. As with
508 overriding locally defined methods, if you do want to do this, you should do it
509 manually, not with Moose.
511 You do not I<need> to have a reader (or accessor) for the attribute in order
512 to delegate to it. Moose will create a means of accessing the value for you,
513 however this will be several times B<less> efficient then if you had given
514 the attribute a reader (or accessor) to use.
516 Below is the documentation for each option format:
522 This is the most common usage for I<handles>. You basically pass a list of
523 method names to be delegated, and Moose will install a delegation method
528 This is the second most common usage for I<handles>. Instead of a list of
529 method names, you pass a HASH ref where each key is the method name you
530 want installed locally, and its value is the name of the original method
531 in the class being delegated to.
533 This can be very useful for recursive classes like trees. Here is a
534 quick example (soon to be expanded into a Moose::Cookbook recipe):
539 has 'node' => (is => 'rw', isa => 'Any');
544 default => sub { [] }
552 parent_node => 'node',
553 siblings => 'children',
557 In this example, the Tree package gets C<parent_node> and C<siblings> methods,
558 which delegate to the C<node> and C<children> methods (respectively) of the Tree
559 instance stored in the C<parent> slot.
563 The regexp option works very similar to the ARRAY option, except that it builds
564 the list of methods for you. It starts by collecting all possible methods of the
565 class being delegated to, then filters that list using the regexp supplied here.
567 B<NOTE:> An I<isa> option is required when using the regexp option format. This
568 is so that we can determine (at compile time) the method list from the class.
569 Without an I<isa> this is just not possible.
573 With the role option, you specify the name of a role whose "interface" then
574 becomes the list of methods to handle. The "interface" can be defined as; the
575 methods of the role and any required methods of the role. It should be noted
576 that this does B<not> include any method modifiers or generated attribute
577 methods (which is consistent with role composition).
581 This is the option to use when you really want to do something funky. You should
582 only use it if you really know what you are doing, as it involves manual
585 This takes a code reference, which should expect two arguments. The first is the
586 attribute meta-object this I<handles> is attached to. The second is the
587 metaclass of the class being delegated to. It expects you to return a hash (not
588 a HASH ref) of the methods you want mapped.
592 =item I<metaclass =E<gt> $metaclass_name>
594 This tells the class to use a custom attribute metaclass for this particular
595 attribute. Custom attribute metaclasses are useful for extending the
596 capabilities of the I<has> keyword: they are the simplest way to extend the MOP,
597 but they are still a fairly advanced topic and too much to cover here, see
598 L<Moose::Cookbook::Meta::Recipe1> for more information.
600 The default behavior here is to just load C<$metaclass_name>; however, we also
601 have a way to alias to a shorter name. This will first look to see if
602 B<Moose::Meta::Attribute::Custom::$metaclass_name> exists. If it does, Moose
603 will then check to see if that has the method C<register_implementation>, which
604 should return the actual name of the custom attribute metaclass. If there is no
605 C<register_implementation> method, it will fall back to using
606 B<Moose::Meta::Attribute::Custom::$metaclass_name> as the metaclass name.
608 =item I<traits =E<gt> [ @role_names ]>
610 This tells Moose to take the list of C<@role_names> and apply them to the
611 attribute meta-object. This is very similar to the I<metaclass> option, but
612 allows you to use more than one extension at a time.
614 See L<TRAIT NAME RESOLUTION> for details on how a trait name is
615 resolved to a class name.
617 Also see L<Moose::Cookbook::Meta::Recipe3> for a metaclass trait
620 =item I<builder> => Str
622 The value of this key is the name of the method that will be called to
623 obtain the value used to initialize the attribute. See the L<builder
624 option docs in Class::MOP::Attribute|Class::MOP::Attribute/builder>
625 for more information.
627 =item I<default> => SCALAR | CODE
629 The value of this key is the default value which will initialize the attribute.
631 NOTE: If the value is a simple scalar (string or number), then it can
632 be just passed as is. However, if you wish to initialize it with a
633 HASH or ARRAY ref, then you need to wrap that inside a CODE reference.
634 See the L<default option docs in
635 Class::MOP::Attribute|Class::MOP::Attribute/default> for more
638 =item I<clearer> => Str
640 Creates a method allowing you to clear the value, see the L<clearer option
641 docs in Class::MOP::Attribute|Class::MOP::Attribute/clearer> for more
644 =item I<predicate> => Str
646 Creates a method to perform a basic test to see if a value has been set in the
647 attribute, see the L<predicate option docs in
648 Class::MOP::Attribute|Class::MOP::Attribute/predicate> for more information.
650 =item I<lazy_build> => (0|1)
652 Automatically define lazy => 1 as well as builder => "_build_$attr", clearer =>
653 "clear_$attr', predicate => 'has_$attr' unless they are already defined.
655 =item I<initializer> => Str
657 This may be a method name (referring to a method on the class with
658 this attribute) or a CODE ref. The initializer is used to set the
659 attribute value on an instance when the attribute is set during
660 instance initialization (but not when the value is being assigned
661 to). See the L<initializer option docs in
662 Class::MOP::Attribute|Class::MOP::Attribute/initializer> for more
667 =item B<has +$name =E<gt> %options>
669 This is variation on the normal attribute creator C<has> which allows you to
670 clone and extend an attribute from a superclass or from a role. Here is an
671 example of the superclass usage:
679 default => 'Hello, I am a Foo'
687 has '+message' => (default => 'Hello I am My::Foo');
689 What is happening here is that B<My::Foo> is cloning the C<message> attribute
690 from its parent class B<Foo>, retaining the C<is =E<gt> 'rw'> and C<isa =E<gt>
691 'Str'> characteristics, but changing the value in C<default>.
693 Here is another example, but within the context of a role:
701 default => 'Hello, I am a Foo'
709 has '+message' => (default => 'Hello I am My::Foo');
711 In this case, we are basically taking the attribute which the role supplied
712 and altering it within the bounds of this feature.
714 Aside from where the attributes come from (one from superclass, the other
715 from a role), this feature works exactly the same. This feature is restricted
716 somewhat, so as to try and force at least I<some> sanity into it. You are only
717 allowed to change the following attributes:
723 Change the default value of an attribute.
727 Change whether the attribute attempts to coerce a value passed to it.
731 Change if the attribute is required to have a value.
733 =item I<documentation>
735 Change the documentation string associated with the attribute.
739 Change if the attribute lazily initializes the slot.
743 You I<are> allowed to change the type without restriction.
745 It is recommended that you use this freedom with caution. We used to
746 only allow for extension only if the type was a subtype of the parent's
747 type, but we felt that was too restrictive and is better left as a
752 You are allowed to B<add> a new C<handles> definition, but you are B<not>
753 allowed to I<change> one.
757 You are allowed to B<add> a new C<builder> definition, but you are B<not>
758 allowed to I<change> one.
762 You are allowed to B<add> a new C<metaclass> definition, but you are
763 B<not> allowed to I<change> one.
767 You are allowed to B<add> additional traits to the C<traits> definition.
768 These traits will be composed into the attribute, but preexisting traits
769 B<are not> overridden, or removed.
773 =item B<before $name|@names =E<gt> sub { ... }>
775 =item B<after $name|@names =E<gt> sub { ... }>
777 =item B<around $name|@names =E<gt> sub { ... }>
779 This three items are syntactic sugar for the before, after, and around method
780 modifier features that L<Class::MOP> provides. More information on these may be
781 found in the L<Class::MOP::Class documentation|Class::MOP::Class/"Method
786 The keyword C<super> is a no-op when called outside of an C<override> method. In
787 the context of an C<override> method, it will call the next most appropriate
788 superclass method with the same arguments as the original method.
790 =item B<override ($name, &sub)>
792 An C<override> method is a way of explicitly saying "I am overriding this
793 method from my superclass". You can call C<super> within this method, and
794 it will work as expected. The same thing I<can> be accomplished with a normal
795 method call and the C<SUPER::> pseudo-package; it is really your choice.
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::Recipe6>.
804 =item B<augment ($name, &sub)>
806 An C<augment> method, is a way of explicitly saying "I am augmenting this
807 method from my superclass". Once again, the details of how C<inner> and
808 C<augment> work is best described in the L<Moose::Cookbook::Basics::Recipe6>.
812 This is the C<Carp::confess> function, and exported here because I use it
817 This is the C<Scalar::Util::blessed> function, it is exported here because I
818 use it all the time. It is highly recommended that this is used instead of
819 C<ref> anywhere you need to test for an object's class name.
823 =head1 METACLASS TRAITS
825 When you use Moose, you can also specify traits which will be applied
828 use Moose -traits => 'My::Trait';
830 This is very similar to the attribute traits feature. When you do
831 this, your class's C<meta> object will have the specified traits
832 applied to it. See L<TRAIT NAME RESOLUTION> for more details.
834 =head1 TRAIT NAME RESOLUTION
836 By default, when given a trait name, Moose simply tries to load a
837 class of the same name. If such a class does not exist, it then looks
838 for for a class matching
839 B<Moose::Meta::$type::Custom::Trait::$trait_name>. The C<$type>
840 variable here will be one of B<Attribute> or B<Class>, depending on
841 what the trait is being applied to.
843 If a class with this long name exists, Moose checks to see if it has
844 the method C<register_implementation>. This method is expected to
845 return the I<real> class name of the trait. If there is no
846 C<register_implementation> method, it will fall back to using
847 B<Moose::Meta::$type::Custom::Trait::$trait> as the trait name.
849 If all this is confusing, take a look at
850 L<Moose::Cookbook::Meta::Recipe3>, which demonstrates how to create an
853 =head1 UNIMPORTING FUNCTIONS
857 Moose offers a way to remove the keywords it exports, through the C<unimport>
858 method. You simply have to say C<no Moose> at the bottom of your code for this
859 to work. Here is an example:
864 has 'first_name' => (is => 'rw', isa => 'Str');
865 has 'last_name' => (is => 'rw', isa => 'Str');
869 $self->first_name . ' ' . $self->last_name
872 no Moose; # keywords are removed from the Person package
874 =head1 EXTENDING AND EMBEDDING MOOSE
876 To learn more about extending Moose, we recommend checking out the
877 "Extending" recipes in the L<Moose::Cookbook>, starting with
878 L<Moose::Cookbook::Extending::Recipe1>, which provides an overview of
879 all the different ways you might extend Moose.
881 =head2 B<< Moose->init_meta(for_class => $class, base_class => $baseclass, metaclass => $metaclass) >>
883 The C<init_meta> method sets up the metaclass object for the class
884 specified by C<for_class>. This method injects a a C<meta> accessor
885 into the class so you can get at this object. It also sets the class's
886 superclass to C<base_class>, with L<Moose::Object> as the default.
888 You can specify an alternate metaclass with the C<metaclass> parameter.
890 For more detail on this topic, see L<Moose::Cookbook::Extending::Recipe2>.
892 This method used to be documented as a function which accepted
893 positional parameters. This calling style will still work for
894 backwards compatibility, but is deprecated.
898 Moose's C<import> method supports the L<Sub::Exporter> form of C<{into =E<gt> $pkg}>
899 and C<{into_level =E<gt> 1}>.
901 B<NOTE>: Doing this is more or less deprecated. Use L<Moose::Exporter>
902 instead, which lets you stack multiple C<Moose.pm>-alike modules
903 sanely. It handles getting the exported functions into the right place
906 =head2 B<throw_error>
908 An alias for C<confess>, used by internally by Moose.
910 =head1 METACLASS COMPATIBILITY AND MOOSE
912 Metaclass compatibility is a thorny subject. You should start by
913 reading the "About Metaclass compatibility" section in the
916 Moose will attempt to resolve a few cases of metaclass incompatibility
917 when you set the superclasses for a class, unlike C<Class::MOP>, which
918 simply dies if the metaclasses are incompatible.
920 In actuality, Moose fixes incompatibility for I<all> of a class's
921 metaclasses, not just the class metaclass. That includes the instance
922 metaclass, attribute metaclass, as well as its constructor class and
923 destructor class. However, for simplicity this discussion will just
924 refer to "metaclass", meaning the class metaclass, most of the time.
926 Moose has two algorithms for fixing metaclass incompatibility.
928 The first algorithm is very simple. If all the metaclass for the
929 parent is a I<subclass> of the child's metaclass, then we simply
930 replace the child's metaclass with the parent's.
932 The second algorithm is more complicated. It tries to determine if the
933 metaclasses only "differ by roles". This means that the parent and
934 child's metaclass share a common ancestor in their respective
935 hierarchies, and that the subclasses under the common ancestor are
936 only different because of role applications. This case is actually
937 fairly common when you mix and match various C<MooseX::*> modules,
938 many of which apply roles to the metaclass.
940 If the parent and child do differ by roles, Moose replaces the
941 metaclass in the child with a newly created metaclass. This metaclass
942 is a subclass of the parent's metaclass, does all of the roles that
943 the child's metaclass did before being replaced. Effectively, this
944 means the new metaclass does all of the roles done by both the
945 parent's and child's original metaclasses.
947 Ultimately, this is all transparent to you except in the case of an
948 unresolvable conflict.
950 =head2 The MooseX:: namespace
952 Generally if you're writing an extension I<for> Moose itself you'll want
953 to put your extension in the C<MooseX::> namespace. This namespace is
954 specifically for extensions that make Moose better or different in some
955 fundamental way. It is traditionally B<not> for a package that just happens
956 to use Moose. This namespace follows from the examples of the C<LWPx::>
957 and C<DBIx::> namespaces that perform the same function for C<LWP> and C<DBI>
966 It should be noted that C<super> and C<inner> B<cannot> be used in the same
967 method. However, they may be combined within the same class hierarchy; see
968 F<t/014_override_augment_inner_super.t> for an example.
970 The reason for this is that C<super> is only valid within a method
971 with the C<override> modifier, and C<inner> will never be valid within an
972 C<override> method. In fact, C<augment> will skip over any C<override> methods
973 when searching for its appropriate C<inner>.
975 This might seem like a restriction, but I am of the opinion that keeping these
976 two features separate (yet interoperable) actually makes them easy to use, since
977 their behavior is then easier to predict. Time will tell whether I am right or
978 not (UPDATE: so far so good).
984 We offer both a mailing list and a very active IRC channel.
986 The mailing list is L<moose@perl.org>. You must be subscribed to send
987 a message. To subscribe, send an empty message to
988 L<moose-subscribe@perl.org>
990 You can also visit us at L<#moose on
991 irc.perl.org|irc://irc.perl.org/#moose>. This channel is quite active,
992 and questions at all levels (on Moose-related topics ;) are welcome.
994 =head1 ACKNOWLEDGEMENTS
998 =item I blame Sam Vilain for introducing me to the insanity that is meta-models.
1000 =item I blame Audrey Tang for then encouraging my meta-model habit in #perl6.
1002 =item Without Yuval "nothingmuch" Kogman this module would not be possible,
1003 and it certainly wouldn't have this name ;P
1005 =item The basis of the TypeContraints module was Rob Kinyon's idea
1006 originally, I just ran with it.
1008 =item Thanks to mst & chansen and the whole #moose posse for all the
1009 early ideas/feature-requests/encouragement/bug-finding.
1011 =item Thanks to David "Theory" Wheeler for meta-discussions and spelling fixes.
1019 =item L<http://www.iinteractive.com/moose>
1021 This is the official web home of Moose, it contains links to our public SVN repository
1022 as well as links to a number of talks and articles on Moose and Moose related
1025 =item The Moose is flying, a tutorial by Randal Schwartz
1027 Part 1 - L<http://www.stonehenge.com/merlyn/LinuxMag/col94.html>
1029 Part 2 - L<http://www.stonehenge.com/merlyn/LinuxMag/col95.html>
1031 =item Several Moose extension modules in the C<MooseX::> namespace.
1033 See L<http://search.cpan.org/search?query=MooseX::> for extensions.
1035 =item Moose stats on ohloh.net - L<http://www.ohloh.net/projects/moose>
1043 =item The Art of the MetaObject Protocol
1045 I mention this in the L<Class::MOP> docs too, this book was critical in
1046 the development of both modules and is highly recommended.
1054 =item L<http://www.cs.utah.edu/plt/publications/oopsla04-gff.pdf>
1056 This paper (suggested by lbr on #moose) was what lead to the implementation
1057 of the C<super>/C<override> and C<inner>/C<augment> features. If you really
1058 want to understand them, I suggest you read this.
1064 All complex software has bugs lurking in it, and this module is no
1065 exception. If you find a bug please either email me, or add the bug
1068 =head1 FEATURE REQUESTS
1070 We are very strict about what features we add to the Moose core, especially
1071 the user-visible features. Instead we have made sure that the underlying
1072 meta-system of Moose is as extensible as possible so that you can add your
1073 own features easily. That said, occasionally there is a feature needed in the
1074 meta-system to support your planned extension, in which case you should
1075 either email the mailing list or join us on irc at #moose to discuss.
1079 Moose is an open project, there are at this point dozens of people who have
1080 contributed, and can contribute. If you have added anything to the Moose
1081 project you have a commit bit on this file and can add your name to the list.
1085 However there are only a few people with the rights to release a new version
1086 of Moose. The Moose Cabal are the people to go to with questions regarding
1087 the wider purview of Moose, and help out maintaining not just the code
1088 but the community as well.
1090 Stevan (stevan) Little E<lt>stevan@iinteractive.comE<gt>
1092 Yuval (nothingmuch) Kogman
1094 Shawn (sartak) Moore
1096 Dave (autarch) Rolsky E<lt>autarch@urth.orgE<gt>
1098 =head2 OTHER CONTRIBUTORS
1102 Adam (Alias) Kennedy
1104 Anders (Debolaz) Nor Berle
1106 Nathan (kolibrie) Gray
1108 Christian (chansen) Hansen
1110 Hans Dieter (confound) Pearcey
1112 Eric (ewilhelm) Wilhelm
1114 Guillermo (groditi) Roditi
1116 Jess (castaway) Robinson
1120 Robert (phaylon) Sedlacek
1124 Scott (konobi) McWhirter
1126 Shlomi (rindolf) Fish
1128 Chris (perigrin) Prather
1130 Wallace (wreis) Reis
1132 Jonathan (jrockway) Rockway
1134 Piotr (dexter) Roszatycki
1136 Sam (mugwump) Vilain
1140 ... and many other #moose folks
1142 =head1 COPYRIGHT AND LICENSE
1144 Copyright 2006-2009 by Infinity Interactive, Inc.
1146 L<http://www.iinteractive.com>
1148 This library is free software; you can redistribute it and/or modify
1149 it under the same terms as Perl itself.