10 $VERSION = eval $VERSION;
11 our $AUTHORITY = 'cpan:STEVAN';
13 use Scalar::Util 'blessed';
18 use Class::MOP 0.82_01;
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($level);
55 Moose->throw_error("Must derive at least one class") unless @_;
57 # this checks the metaclass to make sure
58 # it is correct, sometimes it can get out
59 # of sync when the classes are being built
60 Moose::Meta::Class->initialize($class)->superclasses(@_);
65 Moose::Util::apply_all_roles(Class::MOP::Class->initialize($class), @_);
72 Moose->throw_error('Usage: has \'name\' => ( key => value, ... )')
75 my %options = ( definition_context => _caller_info(), @_ );
76 my $attrs = ( ref($name) eq 'ARRAY' ) ? $name : [ ($name) ];
77 Class::MOP::Class->initialize($class)->add_attribute( $_, %options ) for @$attrs;
82 Moose::Util::add_method_modifier($class, 'before', \@_);
87 Moose::Util::add_method_modifier($class, 'after', \@_);
92 Moose::Util::add_method_modifier($class, 'around', \@_);
100 # This check avoids a recursion loop - see
101 # t/100_bugs/020_super_recursion.t
102 return if defined $SUPER_PACKAGE && $SUPER_PACKAGE ne caller();
103 return unless $SUPER_BODY; $SUPER_BODY->(@SUPER_ARGS);
108 my ( $name, $method ) = @_;
109 Class::MOP::Class->initialize($class)->add_override_method_modifier( $name => $method );
114 our ( %INNER_BODY, %INNER_ARGS );
116 if ( my $body = $INNER_BODY{$pkg} ) {
117 my @args = @{ $INNER_ARGS{$pkg} };
118 local $INNER_ARGS{$pkg};
119 local $INNER_BODY{$pkg};
120 return $body->(@args);
128 my ( $name, $method ) = @_;
129 Class::MOP::Class->initialize($class)->add_augment_method_modifier( $name => $method );
132 Moose::Exporter->setup_import_methods(
134 qw( extends with has before after around override augment)
139 \&Scalar::Util::blessed,
144 # This used to be called as a function. This hack preserves
145 # backwards compatibility.
146 if ( $_[0] ne __PACKAGE__ ) {
147 return __PACKAGE__->init_meta(
157 my $class = $args{for_class}
158 or Moose->throw_error("Cannot call init_meta without specifying a for_class");
159 my $base_class = $args{base_class} || 'Moose::Object';
160 my $metaclass = $args{metaclass} || 'Moose::Meta::Class';
162 Moose->throw_error("The Metaclass $metaclass must be a subclass of Moose::Meta::Class.")
163 unless $metaclass->isa('Moose::Meta::Class');
165 # make a subtype for each Moose class
167 unless find_type_constraint($class);
171 if ( $meta = Class::MOP::get_metaclass_by_name($class) ) {
172 unless ( $meta->isa("Moose::Meta::Class") ) {
173 Moose->throw_error("$class already has a metaclass, but it does not inherit $metaclass ($meta)");
176 # no metaclass, no 'meta' method
178 # now we check whether our ancestors have metaclass, and if so borrow that
179 my ( undef, @isa ) = @{ $class->mro::get_linear_isa };
181 foreach my $ancestor ( @isa ) {
182 my $ancestor_meta = Class::MOP::get_metaclass_by_name($ancestor) || next;
184 my $ancestor_meta_class = ($ancestor_meta->is_immutable
185 ? $ancestor_meta->get_mutable_metaclass_name
186 : ref($ancestor_meta));
188 # if we have an ancestor metaclass that inherits $metaclass, we use
189 # that. This is like _fix_metaclass_incompatibility, but we can do it now.
191 # the case of having an ancestry is not very common, but arises in
193 unless ( $metaclass->isa( $ancestor_meta_class ) ) {
194 if ( $ancestor_meta_class->isa($metaclass) ) {
195 $metaclass = $ancestor_meta_class;
200 $meta = $metaclass->initialize($class);
203 if ( $class->can('meta') ) {
204 # check 'meta' method
206 # it may be inherited
209 # this is the case where the metaclass pragma
210 # was used before the 'use Moose' statement to
211 # override a specific class
212 my $method_meta = $class->meta;
214 ( blessed($method_meta) && $method_meta->isa('Moose::Meta::Class') )
215 || Moose->throw_error("$class already has a &meta function, but it does not return a Moose::Meta::Class ($meta)");
217 $meta = $method_meta;
220 unless ( $meta->has_method("meta") ) { # don't overwrite
221 # also check for inherited non moose 'meta' method?
222 # FIXME also skip this if the user requested by passing an option
225 # re-initialize so it inherits properly
226 $metaclass->initialize( ref($_[0]) || $_[0] );
231 # make sure they inherit from Moose::Object
232 $meta->superclasses($base_class)
233 unless $meta->superclasses();
238 # This may be used in some older MooseX extensions.
240 goto &Moose::Exporter::_get_caller;
243 ## make 'em all immutable
246 inline_constructor => 1,
247 constructor_name => "_new",
248 # these are Class::MOP accessors, so they need inlining
249 inline_accessors => 1
250 ) for grep { $_->is_mutable }
253 Moose::Meta::Attribute
255 Moose::Meta::Instance
257 Moose::Meta::TypeCoercion
258 Moose::Meta::TypeCoercion::Union
261 Moose::Meta::Method::Accessor
262 Moose::Meta::Method::Constructor
263 Moose::Meta::Method::Destructor
264 Moose::Meta::Method::Overridden
265 Moose::Meta::Method::Augmented
268 Moose::Meta::Role::Method
269 Moose::Meta::Role::Method::Required
271 Moose::Meta::Role::Composite
273 Moose::Meta::Role::Application
274 Moose::Meta::Role::Application::RoleSummation
275 Moose::Meta::Role::Application::ToClass
276 Moose::Meta::Role::Application::ToRole
277 Moose::Meta::Role::Application::ToInstance
288 Moose - A postmodern object system for Perl 5
293 use Moose; # automatically turns on strict and warnings
295 has 'x' => (is => 'rw', isa => 'Int');
296 has 'y' => (is => 'rw', isa => 'Int');
309 has 'z' => (is => 'rw', isa => 'Int');
311 after 'clear' => sub {
318 Moose is an extension of the Perl 5 object system.
320 The main goal of Moose is to make Perl 5 Object Oriented programming
321 easier, more consistent and less tedious. With Moose you can to think
322 more about what you want to do and less about the mechanics of OOP.
324 Additionally, Moose is built on top of L<Class::MOP>, which is a
325 metaclass system for Perl 5. This means that Moose not only makes
326 building normal Perl 5 objects better, but it provides the power of
327 metaclass programming as well.
331 If you're new to Moose, the best place to start is the
332 L<Moose::Manual> docs, followed by the L<Moose::Cookbook>. The intro
333 will show you what Moose is, and how it makes Perl 5 OO better.
335 The cookbook recipes on Moose basics will get you up to speed with
336 many of Moose's features quickly. Once you have an idea of what Moose
337 can do, you can use the API documentation to get more detail on
338 features which interest you.
340 =head2 Moose Extensions
342 The C<MooseX::> namespace is the official place to find Moose extensions.
343 These extensions can be found on the CPAN. The easiest way to find them
344 is to search for them (L<http://search.cpan.org/search?query=MooseX::>),
345 or to examine L<Task::Moose> which aims to keep an up-to-date, easily
346 installable list of Moose extensions.
348 =head1 BUILDING CLASSES WITH MOOSE
350 Moose makes every attempt to provide as much convenience as possible during
351 class construction/definition, but still stay out of your way if you want it
352 to. Here are a few items to note when building classes with Moose.
354 Unless specified with C<extends>, any class which uses Moose will
355 inherit from L<Moose::Object>.
357 Moose will also manage all attributes (including inherited ones) that are
358 defined with C<has>. And (assuming you call C<new>, which is inherited from
359 L<Moose::Object>) this includes properly initializing all instance slots,
360 setting defaults where appropriate, and performing any type constraint checking
363 =head1 PROVIDED METHODS
365 Moose provides a number of methods to all your classes, mostly through the
366 inheritance of L<Moose::Object>. There is however, one exception.
372 This is a method which provides access to the current class's metaclass.
376 =head1 EXPORTED FUNCTIONS
378 Moose will export a number of functions into the class's namespace which
379 may then be used to set up the class. These functions all work directly
380 on the current class.
384 =item B<extends (@superclasses)>
386 This function will set the superclass(es) for the current class.
388 This approach is recommended instead of C<use base>, because C<use base>
389 actually C<push>es onto the class's C<@ISA>, whereas C<extends> will
390 replace it. This is important to ensure that classes which do not have
391 superclasses still properly inherit from L<Moose::Object>.
393 =item B<with (@roles)>
395 This will apply a given set of C<@roles> to the local class.
397 =item B<has $name|@$names =E<gt> %options>
399 This will install an attribute of a given C<$name> into the current class. If
400 the first parameter is an array reference, it will create an attribute for
401 every C<$name> in the list. The C<%options> are the same as those provided by
402 L<Class::MOP::Attribute>, in addition to the list below which are provided by
403 Moose (L<Moose::Meta::Attribute> to be more specific):
407 =item I<is =E<gt> 'rw'|'ro'>
409 The I<is> option accepts either I<rw> (for read/write) or I<ro> (for read
410 only). These will create either a read/write accessor or a read-only
411 accessor respectively, using the same name as the C<$name> of the attribute.
413 If you need more control over how your accessors are named, you can
414 use the L<reader|Class::MOP::Attribute/reader>,
415 L<writer|Class::MOP::Attribute/writer> and
416 L<accessor|Class::MOP::Attribute/accessor> options inherited from
417 L<Class::MOP::Attribute>, however if you use those, you won't need the
420 =item I<isa =E<gt> $type_name>
422 The I<isa> option uses Moose's type constraint facilities to set up runtime
423 type checking for this attribute. Moose will perform the checks during class
424 construction, and within any accessors. The C<$type_name> argument must be a
425 string. The string may be either a class name or a type defined using
426 Moose's type definition features. (Refer to L<Moose::Util::TypeConstraints>
427 for information on how to define a new type, and how to retrieve type meta-data).
429 =item I<coerce =E<gt> (1|0)>
431 This will attempt to use coercion with the supplied type constraint to change
432 the value passed into any accessors or constructors. You B<must> have supplied
433 a type constraint in order for this to work. See L<Moose::Cookbook::Basics::Recipe5>
436 =item I<does =E<gt> $role_name>
438 This will accept the name of a role which the value stored in this attribute
439 is expected to have consumed.
441 =item I<required =E<gt> (1|0)>
443 This marks the attribute as being required. This means a I<defined> value must be
444 supplied during class construction, and the attribute may never be set to
445 C<undef> with an accessor.
447 =item I<weak_ref =E<gt> (1|0)>
449 This will tell the class to store the value of this attribute as a weakened
450 reference. If an attribute is a weakened reference, it B<cannot> also be
453 =item I<lazy =E<gt> (1|0)>
455 This will tell the class to not create this slot until absolutely necessary.
456 If an attribute is marked as lazy it B<must> have a default supplied.
458 =item I<auto_deref =E<gt> (1|0)>
460 This tells the accessor whether to automatically dereference the value returned.
461 This is only legal if your C<isa> option is either C<ArrayRef> or C<HashRef>.
463 =item I<trigger =E<gt> $code>
465 The I<trigger> option is a CODE reference which will be called after
466 the value of the attribute is set. The CODE ref will be passed the
467 instance itself and the updated value. You B<cannot> have a trigger on
468 a read-only attribute.
470 B<NOTE:> Triggers will only fire when you B<assign> to the attribute,
471 either in the constructor, or using the writer. Default and built values will
472 B<not> cause the trigger to be fired.
474 =item I<handles =E<gt> ARRAY | HASH | REGEXP | ROLE | CODE>
476 The I<handles> option provides Moose classes with automated delegation features.
477 This is a pretty complex and powerful option. It accepts many different option
478 formats, each with its own benefits and drawbacks.
480 B<NOTE:> The class being delegated to does not need to be a Moose based class,
481 which is why this feature is especially useful when wrapping non-Moose classes.
483 All I<handles> option formats share the following traits:
485 You cannot override a locally defined method with a delegated method; an
486 exception will be thrown if you try. That is to say, if you define C<foo> in
487 your class, you cannot override it with a delegated C<foo>. This is almost never
488 something you would want to do, and if it is, you should do it by hand and not
491 You cannot override any of the methods found in Moose::Object, or the C<BUILD>
492 and C<DEMOLISH> methods. These will not throw an exception, but will silently
493 move on to the next method in the list. My reasoning for this is that you would
494 almost never want to do this, since it usually breaks your class. As with
495 overriding locally defined methods, if you do want to do this, you should do it
496 manually, not with Moose.
498 You do not I<need> to have a reader (or accessor) for the attribute in order
499 to delegate to it. Moose will create a means of accessing the value for you,
500 however this will be several times B<less> efficient then if you had given
501 the attribute a reader (or accessor) to use.
503 Below is the documentation for each option format:
509 This is the most common usage for I<handles>. You basically pass a list of
510 method names to be delegated, and Moose will install a delegation method
515 This is the second most common usage for I<handles>. Instead of a list of
516 method names, you pass a HASH ref where each key is the method name you
517 want installed locally, and its value is the name of the original method
518 in the class being delegated to.
520 This can be very useful for recursive classes like trees. Here is a
521 quick example (soon to be expanded into a Moose::Cookbook recipe):
526 has 'node' => (is => 'rw', isa => 'Any');
531 default => sub { [] }
539 parent_node => 'node',
540 siblings => 'children',
544 In this example, the Tree package gets C<parent_node> and C<siblings> methods,
545 which delegate to the C<node> and C<children> methods (respectively) of the Tree
546 instance stored in the C<parent> slot.
550 The regexp option works very similar to the ARRAY option, except that it builds
551 the list of methods for you. It starts by collecting all possible methods of the
552 class being delegated to, then filters that list using the regexp supplied here.
554 B<NOTE:> An I<isa> option is required when using the regexp option format. This
555 is so that we can determine (at compile time) the method list from the class.
556 Without an I<isa> this is just not possible.
560 With the role option, you specify the name of a role whose "interface" then
561 becomes the list of methods to handle. The "interface" can be defined as; the
562 methods of the role and any required methods of the role. It should be noted
563 that this does B<not> include any method modifiers or generated attribute
564 methods (which is consistent with role composition).
568 This is the option to use when you really want to do something funky. You should
569 only use it if you really know what you are doing, as it involves manual
572 This takes a code reference, which should expect two arguments. The first is the
573 attribute meta-object this I<handles> is attached to. The second is the
574 metaclass of the class being delegated to. It expects you to return a hash (not
575 a HASH ref) of the methods you want mapped.
579 =item I<metaclass =E<gt> $metaclass_name>
581 This tells the class to use a custom attribute metaclass for this particular
582 attribute. Custom attribute metaclasses are useful for extending the
583 capabilities of the I<has> keyword: they are the simplest way to extend the MOP,
584 but they are still a fairly advanced topic and too much to cover here, see
585 L<Moose::Cookbook::Meta::Recipe1> for more information.
587 The default behavior here is to just load C<$metaclass_name>; however, we also
588 have a way to alias to a shorter name. This will first look to see if
589 B<Moose::Meta::Attribute::Custom::$metaclass_name> exists. If it does, Moose
590 will then check to see if that has the method C<register_implementation>, which
591 should return the actual name of the custom attribute metaclass. If there is no
592 C<register_implementation> method, it will fall back to using
593 B<Moose::Meta::Attribute::Custom::$metaclass_name> as the metaclass name.
595 =item I<traits =E<gt> [ @role_names ]>
597 This tells Moose to take the list of C<@role_names> and apply them to the
598 attribute meta-object. This is very similar to the I<metaclass> option, but
599 allows you to use more than one extension at a time.
601 See L<TRAIT NAME RESOLUTION> for details on how a trait name is
602 resolved to a class name.
604 Also see L<Moose::Cookbook::Meta::Recipe3> for a metaclass trait
607 =item I<builder> => Str
609 The value of this key is the name of the method that will be called to
610 obtain the value used to initialize the attribute. See the L<builder
611 option docs in Class::MOP::Attribute|Class::MOP::Attribute/builder>
612 and/or L<Moose::Cookbook::Basics::Recipe9> for more information.
614 =item I<default> => SCALAR | CODE
616 The value of this key is the default value which will initialize the attribute.
618 NOTE: If the value is a simple scalar (string or number), then it can
619 be just passed as is. However, if you wish to initialize it with a
620 HASH or ARRAY ref, then you need to wrap that inside a CODE reference.
621 See the L<default option docs in
622 Class::MOP::Attribute|Class::MOP::Attribute/default> for more
625 =item I<clearer> => Str
627 Creates a method allowing you to clear the value, see the L<clearer option
628 docs in Class::MOP::Attribute|Class::MOP::Attribute/clearer> for more
631 =item I<predicate> => Str
633 Creates a method to perform a basic test to see if a value has been set in the
634 attribute, see the L<predicate option docs in
635 Class::MOP::Attribute|Class::MOP::Attribute/predicate> for more information.
637 =item I<lazy_build> => (0|1)
639 Automatically define lazy => 1 as well as builder => "_build_$attr", clearer =>
640 "clear_$attr', predicate => 'has_$attr' unless they are already defined.
642 =item I<initializer> => Str
644 This may be a method name (referring to a method on the class with
645 this attribute) or a CODE ref. The initializer is used to set the
646 attribute value on an instance when the attribute is set during
647 instance initialization (but not when the value is being assigned
648 to). See the L<initializer option docs in
649 Class::MOP::Attribute|Class::MOP::Attribute/initializer> for more
654 =item B<has +$name =E<gt> %options>
656 This is variation on the normal attribute creator C<has> which allows you to
657 clone and extend an attribute from a superclass or from a role. Here is an
658 example of the superclass usage:
666 default => 'Hello, I am a Foo'
674 has '+message' => (default => 'Hello I am My::Foo');
676 What is happening here is that B<My::Foo> is cloning the C<message> attribute
677 from its parent class B<Foo>, retaining the C<is =E<gt> 'rw'> and C<isa =E<gt>
678 'Str'> characteristics, but changing the value in C<default>.
680 Here is another example, but within the context of a role:
688 default => 'Hello, I am a Foo'
696 has '+message' => (default => 'Hello I am My::Foo');
698 In this case, we are basically taking the attribute which the role supplied
699 and altering it within the bounds of this feature.
701 Aside from where the attributes come from (one from superclass, the other
702 from a role), this feature works exactly the same. This feature is restricted
703 somewhat, so as to try and force at least I<some> sanity into it. You are only
704 allowed to change the following attributes:
710 Change the default value of an attribute.
714 Change whether the attribute attempts to coerce a value passed to it.
718 Change if the attribute is required to have a value.
720 =item I<documentation>
722 Change the documentation string associated with the attribute.
726 Change if the attribute lazily initializes the slot.
730 You I<are> allowed to change the type without restriction.
732 It is recommended that you use this freedom with caution. We used to
733 only allow for extension only if the type was a subtype of the parent's
734 type, but we felt that was too restrictive and is better left as a
739 You are allowed to B<add> a new C<handles> definition, but you are B<not>
740 allowed to I<change> one.
744 You are allowed to B<add> a new C<builder> definition, but you are B<not>
745 allowed to I<change> one.
749 You are allowed to B<add> a new C<metaclass> definition, but you are
750 B<not> allowed to I<change> one.
754 You are allowed to B<add> additional traits to the C<traits> definition.
755 These traits will be composed into the attribute, but preexisting traits
756 B<are not> overridden, or removed.
760 =item B<before $name|@names =E<gt> sub { ... }>
762 =item B<after $name|@names =E<gt> sub { ... }>
764 =item B<around $name|@names =E<gt> sub { ... }>
766 This three items are syntactic sugar for the before, after, and around method
767 modifier features that L<Class::MOP> provides. More information on these may be
768 found in the L<Class::MOP::Class documentation|Class::MOP::Class/"Method
773 The keyword C<super> is a no-op when called outside of an C<override> method. In
774 the context of an C<override> method, it will call the next most appropriate
775 superclass method with the same arguments as the original method.
777 =item B<override ($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<inner>, much like C<super>, is a no-op outside of the context of
787 an C<augment> method. You can think of C<inner> as being the inverse of
788 C<super>; the details of how C<inner> and C<augment> work is best described in
789 the L<Moose::Cookbook::Basics::Recipe6>.
791 =item B<augment ($name, &sub)>
793 An C<augment> method, is a way of explicitly saying "I am augmenting this
794 method from my superclass". Once again, the details of how C<inner> and
795 C<augment> work is best described in the L<Moose::Cookbook::Basics::Recipe6>.
799 This is the C<Carp::confess> function, and exported here because I use it
804 This is the C<Scalar::Util::blessed> function, it is exported here because I
805 use it all the time. It is highly recommended that this is used instead of
806 C<ref> anywhere you need to test for an object's class name.
812 When you use Moose, you can specify which metaclass to use:
814 use Moose -metaclass => 'My::Meta::Class';
816 You can also specify traits which will be applied to your metaclass:
818 use Moose -traits => 'My::Trait';
820 This is very similar to the attribute traits feature. When you do
821 this, your class's C<meta> object will have the specified traits
822 applied to it. See L<TRAIT NAME RESOLUTION> for more details.
824 =head2 Trait Name Resolution
826 By default, when given a trait name, Moose simply tries to load a
827 class of the same name. If such a class does not exist, it then looks
828 for for a class matching
829 B<Moose::Meta::$type::Custom::Trait::$trait_name>. The C<$type>
830 variable here will be one of B<Attribute> or B<Class>, depending on
831 what the trait is being applied to.
833 If a class with this long name exists, Moose checks to see if it has
834 the method C<register_implementation>. This method is expected to
835 return the I<real> class name of the trait. If there is no
836 C<register_implementation> method, it will fall back to using
837 B<Moose::Meta::$type::Custom::Trait::$trait> as the trait name.
839 If all this is confusing, take a look at
840 L<Moose::Cookbook::Meta::Recipe3>, which demonstrates how to create an
843 =head1 UNIMPORTING FUNCTIONS
847 Moose offers a way to remove the keywords it exports, through the C<unimport>
848 method. You simply have to say C<no Moose> at the bottom of your code for this
849 to work. Here is an example:
854 has 'first_name' => (is => 'rw', isa => 'Str');
855 has 'last_name' => (is => 'rw', isa => 'Str');
859 $self->first_name . ' ' . $self->last_name
862 no Moose; # keywords are removed from the Person package
864 =head1 EXTENDING AND EMBEDDING MOOSE
866 To learn more about extending Moose, we recommend checking out the
867 "Extending" recipes in the L<Moose::Cookbook>, starting with
868 L<Moose::Cookbook::Extending::Recipe1>, which provides an overview of
869 all the different ways you might extend Moose.
871 =head2 B<< Moose->init_meta(for_class => $class, base_class => $baseclass, metaclass => $metaclass) >>
873 The C<init_meta> method sets up the metaclass object for the class
874 specified by C<for_class>. This method injects a a C<meta> accessor
875 into the class so you can get at this object. It also sets the class's
876 superclass to C<base_class>, with L<Moose::Object> as the default.
878 C<init_meta> returns the metaclass object for C<$class>.
880 You can specify an alternate metaclass with the C<metaclass> option.
882 For more detail on this topic, see L<Moose::Cookbook::Extending::Recipe2>.
884 This method used to be documented as a function which accepted
885 positional parameters. This calling style will still work for
886 backwards compatibility, but is deprecated.
890 Moose's C<import> method supports the L<Sub::Exporter> form of C<{into =E<gt> $pkg}>
891 and C<{into_level =E<gt> 1}>.
893 B<NOTE>: Doing this is more or less deprecated. Use L<Moose::Exporter>
894 instead, which lets you stack multiple C<Moose.pm>-alike modules
895 sanely. It handles getting the exported functions into the right place
898 =head2 B<throw_error>
900 An alias for C<confess>, used by internally by Moose.
902 =head1 METACLASS COMPATIBILITY AND MOOSE
904 Metaclass compatibility is a thorny subject. You should start by
905 reading the "About Metaclass compatibility" section in the
908 Moose will attempt to resolve a few cases of metaclass incompatibility
909 when you set the superclasses for a class, unlike C<Class::MOP>, which
910 simply dies if the metaclasses are incompatible.
912 In actuality, Moose fixes incompatibility for I<all> of a class's
913 metaclasses, not just the class metaclass. That includes the instance
914 metaclass, attribute metaclass, as well as its constructor class and
915 destructor class. However, for simplicity this discussion will just
916 refer to "metaclass", meaning the class metaclass, most of the time.
918 Moose has two algorithms for fixing metaclass incompatibility.
920 The first algorithm is very simple. If all the metaclass for the
921 parent is a I<subclass> of the child's metaclass, then we simply
922 replace the child's metaclass with the parent's.
924 The second algorithm is more complicated. It tries to determine if the
925 metaclasses only "differ by roles". This means that the parent and
926 child's metaclass share a common ancestor in their respective
927 hierarchies, and that the subclasses under the common ancestor are
928 only different because of role applications. This case is actually
929 fairly common when you mix and match various C<MooseX::*> modules,
930 many of which apply roles to the metaclass.
932 If the parent and child do differ by roles, Moose replaces the
933 metaclass in the child with a newly created metaclass. This metaclass
934 is a subclass of the parent's metaclass, does all of the roles that
935 the child's metaclass did before being replaced. Effectively, this
936 means the new metaclass does all of the roles done by both the
937 parent's and child's original metaclasses.
939 Ultimately, this is all transparent to you except in the case of an
940 unresolvable conflict.
942 =head2 The MooseX:: namespace
944 Generally if you're writing an extension I<for> Moose itself you'll want
945 to put your extension in the C<MooseX::> namespace. This namespace is
946 specifically for extensions that make Moose better or different in some
947 fundamental way. It is traditionally B<not> for a package that just happens
948 to use Moose. This namespace follows from the examples of the C<LWPx::>
949 and C<DBIx::> namespaces that perform the same function for C<LWP> and C<DBI>
958 It should be noted that C<super> and C<inner> B<cannot> be used in the same
959 method. However, they may be combined within the same class hierarchy; see
960 F<t/014_override_augment_inner_super.t> for an example.
962 The reason for this is that C<super> is only valid within a method
963 with the C<override> modifier, and C<inner> will never be valid within an
964 C<override> method. In fact, C<augment> will skip over any C<override> methods
965 when searching for its appropriate C<inner>.
967 This might seem like a restriction, but I am of the opinion that keeping these
968 two features separate (yet interoperable) actually makes them easy to use, since
969 their behavior is then easier to predict. Time will tell whether I am right or
970 not (UPDATE: so far so good).
976 We offer both a mailing list and a very active IRC channel.
978 The mailing list is L<moose@perl.org>. You must be subscribed to send
979 a message. To subscribe, send an empty message to
980 L<moose-subscribe@perl.org>
982 You can also visit us at L<#moose on
983 irc.perl.org|irc://irc.perl.org/#moose>. This channel is quite active,
984 and questions at all levels (on Moose-related topics ;) are welcome.
986 =head1 ACKNOWLEDGEMENTS
990 =item I blame Sam Vilain for introducing me to the insanity that is meta-models.
992 =item I blame Audrey Tang for then encouraging my meta-model habit in #perl6.
994 =item Without Yuval "nothingmuch" Kogman this module would not be possible,
995 and it certainly wouldn't have this name ;P
997 =item The basis of the TypeContraints module was Rob Kinyon's idea
998 originally, I just ran with it.
1000 =item Thanks to mst & chansen and the whole #moose posse for all the
1001 early ideas/feature-requests/encouragement/bug-finding.
1003 =item Thanks to David "Theory" Wheeler for meta-discussions and spelling fixes.
1011 =item L<http://www.iinteractive.com/moose>
1013 This is the official web home of Moose, it contains links to our public SVN repository
1014 as well as links to a number of talks and articles on Moose and Moose related
1017 =item The Moose is flying, a tutorial by Randal Schwartz
1019 Part 1 - L<http://www.stonehenge.com/merlyn/LinuxMag/col94.html>
1021 Part 2 - L<http://www.stonehenge.com/merlyn/LinuxMag/col95.html>
1023 =item Several Moose extension modules in the C<MooseX::> namespace.
1025 See L<http://search.cpan.org/search?query=MooseX::> for extensions.
1027 =item Moose stats on ohloh.net - L<http://www.ohloh.net/projects/moose>
1035 =item The Art of the MetaObject Protocol
1037 I mention this in the L<Class::MOP> docs too, this book was critical in
1038 the development of both modules and is highly recommended.
1046 =item L<http://www.cs.utah.edu/plt/publications/oopsla04-gff.pdf>
1048 This paper (suggested by lbr on #moose) was what lead to the implementation
1049 of the C<super>/C<override> and C<inner>/C<augment> features. If you really
1050 want to understand them, I suggest you read this.
1056 All complex software has bugs lurking in it, and this module is no
1059 Please report any bugs to C<bug-moose@rt.cpan.org>, or through the web
1060 interface at L<http://rt.cpan.org>.
1062 =head1 FEATURE REQUESTS
1064 We are very strict about what features we add to the Moose core, especially
1065 the user-visible features. Instead we have made sure that the underlying
1066 meta-system of Moose is as extensible as possible so that you can add your
1067 own features easily.
1069 That said, occasionally there is a feature needed in the meta-system
1070 to support your planned extension, in which case you should either
1071 email the mailing list (moose@perl.org) or join us on IRC at
1072 L<irc://irc.perl.org/#moose> to discuss. The
1073 L<Moose::Manual::Contributing> has more detail about how and when you
1078 Moose is an open project, there are at this point dozens of people who have
1079 contributed, and can contribute. If you have added anything to the Moose
1080 project you have a commit bit on this file and can add your name to the list.
1084 However there are only a few people with the rights to release a new version
1085 of Moose. The Moose Cabal are the people to go to with questions regarding
1086 the wider purview of Moose, and help out maintaining not just the code
1087 but the community as well.
1089 Stevan (stevan) Little E<lt>stevan@iinteractive.comE<gt>
1091 Yuval (nothingmuch) Kogman
1093 Shawn (sartak) Moore
1095 Dave (autarch) Rolsky E<lt>autarch@urth.orgE<gt>
1097 =head2 OTHER CONTRIBUTORS
1101 Adam (Alias) Kennedy
1103 Anders (Debolaz) Nor Berle
1105 Nathan (kolibrie) Gray
1107 Christian (chansen) Hansen
1109 Hans Dieter (confound) Pearcey
1111 Eric (ewilhelm) Wilhelm
1113 Guillermo (groditi) Roditi
1115 Jess (castaway) Robinson
1119 Robert (phaylon) Sedlacek
1123 Scott (konobi) McWhirter
1125 Shlomi (rindolf) Fish
1127 Chris (perigrin) Prather
1129 Wallace (wreis) Reis
1131 Jonathan (jrockway) Rockway
1133 Piotr (dexter) Roszatycki
1135 Sam (mugwump) Vilain
1139 ... and many other #moose folks
1141 =head1 COPYRIGHT AND LICENSE
1143 Copyright 2006-2009 by Infinity Interactive, Inc.
1145 L<http://www.iinteractive.com>
1147 This library is free software; you can redistribute it and/or modify
1148 it under the same terms as Perl itself.