8 our $AUTHORITY = 'cpan:STEVAN';
10 use Scalar::Util 'blessed';
11 use Carp 'confess', 'croak', 'cluck';
17 use Moose::Meta::Class;
18 use Moose::Meta::TypeConstraint;
19 use Moose::Meta::TypeCoercion;
20 use Moose::Meta::Attribute;
21 use Moose::Meta::Instance;
25 use Moose::Meta::Role;
26 use Moose::Meta::Role::Composite;
27 use Moose::Meta::Role::Application;
28 use Moose::Meta::Role::Application::RoleSummation;
29 use Moose::Meta::Role::Application::ToClass;
30 use Moose::Meta::Role::Application::ToRole;
31 use Moose::Meta::Role::Application::ToInstance;
32 use Moose::Meta::Role::Application::ToMetaclassInstance;
34 use Moose::Util::TypeConstraints;
40 croak "Must derive at least one class" unless @_;
43 foreach my $super (@supers) {
44 Class::MOP::load_class($super);
45 croak "You cannot inherit from a Moose Role ($super)"
46 if $super->can('meta') &&
47 blessed $super->meta &&
48 $super->meta->isa('Moose::Meta::Role')
53 # this checks the metaclass to make sure
54 # it is correct, sometimes it can get out
55 # of sync when the classes are being built
56 my $meta = Moose::Meta::Class->initialize($class)->_fix_metaclass_incompatability(@supers);
57 $meta->superclasses(@supers);
62 Moose::Util::apply_all_roles(Class::MOP::Class->initialize($class), @_);
68 croak 'Usage: has \'name\' => ( key => value, ... )' if @_ == 1;
70 my $attrs = ( ref($name) eq 'ARRAY' ) ? $name : [ ($name) ];
71 Class::MOP::Class->initialize($class)->add_attribute( $_, %options ) for @$attrs;
76 Moose::Util::add_method_modifier($class, 'before', \@_);
81 Moose::Util::add_method_modifier($class, 'after', \@_);
86 Moose::Util::add_method_modifier($class, 'around', \@_);
90 return unless our $SUPER_BODY; $SUPER_BODY->(our @SUPER_ARGS);
95 my ( $name, $method ) = @_;
96 Class::MOP::Class->initialize($class)->add_override_method_modifier( $name => $method );
101 our ( %INNER_BODY, %INNER_ARGS );
103 if ( my $body = $INNER_BODY{$pkg} ) {
104 my @args = @{ $INNER_ARGS{$pkg} };
105 local $INNER_ARGS{$pkg};
106 local $INNER_BODY{$pkg};
107 return $body->(@args);
115 my ( $name, $method ) = @_;
116 Class::MOP::Class->initialize($class)->add_augment_method_modifier( $name => $method );
121 cluck "The make_immutable keyword has been deprecated, " .
122 "please go back to __PACKAGE__->meta->make_immutable\n";
123 Class::MOP::Class->initialize($class)->make_immutable(@_);
126 Moose::Exporter->setup_import_methods(
128 qw( extends with has before after around override augment make_immutable )
133 \&Scalar::Util::blessed,
138 # This used to be called as a function. This hack preserves
139 # backwards compatibility.
140 if ( $_[0] ne __PACKAGE__ ) {
141 return __PACKAGE__->init_meta(
151 my $class = $args{for_class}
152 or confess "Cannot call init_meta without specifying a for_class";
153 my $base_class = $args{base_class} || 'Moose::Object';
154 my $metaclass = $args{metaclass} || 'Moose::Meta::Class';
157 "The Metaclass $metaclass must be a subclass of Moose::Meta::Class."
158 unless $metaclass->isa('Moose::Meta::Class');
160 # make a subtype for each Moose class
162 unless find_type_constraint($class);
166 if ( $meta = Class::MOP::get_metaclass_by_name($class) ) {
167 unless ( $meta->isa("Moose::Meta::Class") ) {
168 confess "$class already has a metaclass, but it does not inherit $metaclass ($meta)";
171 # no metaclass, no 'meta' method
173 # now we check whether our ancestors have metaclass, and if so borrow that
174 my ( undef, @isa ) = @{ $class->mro::get_linear_isa };
176 foreach my $ancestor ( @isa ) {
177 my $ancestor_meta = Class::MOP::get_metaclass_by_name($ancestor) || next;
179 my $ancestor_meta_class = ($ancestor_meta->is_immutable
180 ? $ancestor_meta->get_mutable_metaclass_name
181 : ref($ancestor_meta));
183 # if we have an ancestor metaclass that inherits $metaclass, we use
184 # that. This is like _fix_metaclass_incompatability, but we can do it now.
186 # the case of having an ancestry is not very common, but arises in
188 unless ( $metaclass->isa( $ancestor_meta_class ) ) {
189 if ( $ancestor_meta_class->isa($metaclass) ) {
190 $metaclass = $ancestor_meta_class;
195 $meta = $metaclass->initialize($class);
198 if ( $class->can('meta') ) {
199 # check 'meta' method
201 # it may be inherited
204 # this is the case where the metaclass pragma
205 # was used before the 'use Moose' statement to
206 # override a specific class
207 my $method_meta = $class->meta;
209 ( blessed($method_meta) && $method_meta->isa('Moose::Meta::Class') )
210 || confess "$class already has a &meta function, but it does not return a Moose::Meta::Class ($meta)";
212 $meta = $method_meta;
215 unless ( $meta->has_method("meta") ) { # don't overwrite
216 # also check for inherited non moose 'meta' method?
217 # FIXME also skip this if the user requested by passing an option
220 # re-initialize so it inherits properly
221 $metaclass->initialize( ref($_[0]) || $_[0] );
226 # make sure they inherit from Moose::Object
227 $meta->superclasses($base_class)
228 unless $meta->superclasses();
233 # This may be used in some older MooseX extensions.
235 goto &Moose::Exporter::_get_caller;
238 ## make 'em all immutable
240 $_->meta->make_immutable(
241 inline_constructor => 1,
242 constructor_name => "_new",
243 inline_accessors => 1, # these are Class::MOP accessors, so they need inlining
246 Moose::Meta::Attribute
248 Moose::Meta::Instance
250 Moose::Meta::TypeConstraint
251 Moose::Meta::TypeConstraint::Union
252 Moose::Meta::TypeConstraint::Parameterized
253 Moose::Meta::TypeConstraint::Parameterizable
254 Moose::Meta::TypeConstraint::Enum
255 Moose::Meta::TypeConstraint::Class
256 Moose::Meta::TypeConstraint::Role
257 Moose::Meta::TypeConstraint::Registry
258 Moose::Meta::TypeCoercion
259 Moose::Meta::TypeCoercion::Union
262 Moose::Meta::Method::Accessor
263 Moose::Meta::Method::Constructor
264 Moose::Meta::Method::Destructor
265 Moose::Meta::Method::Overriden
266 Moose::Meta::Method::Augmented
269 Moose::Meta::Role::Method
270 Moose::Meta::Role::Method::Required
272 Moose::Meta::Role::Composite
274 Moose::Meta::Role::Application
275 Moose::Meta::Role::Application::RoleSummation
276 Moose::Meta::Role::Application::ToClass
277 Moose::Meta::Role::Application::ToRole
278 Moose::Meta::Role::Application::ToInstance
279 Moose::Meta::Role::Application::ToMetaclassInstance
290 Moose - A postmodern object system for Perl 5
295 use Moose; # automatically turns on strict and warnings
297 has 'x' => (is => 'rw', isa => 'Int');
298 has 'y' => (is => 'rw', isa => 'Int');
311 has 'z' => (is => 'rw', isa => 'Int');
313 after 'clear' => sub {
320 Moose is an extension of the Perl 5 object system.
322 The main goal of Moose is to make Perl 5 Object Oriented programming
323 easier, more consistent and less tedious. With Moose you can to think
324 more about what you want to do and less about the mechanics of OOP.
326 Additionally, Moose is built on top of L<Class::MOP>, which is a
327 metaclass system for Perl 5. This means that Moose not only makes
328 building normal Perl 5 objects better, but it provides the power of
329 metaclass programming as well.
333 If you're new to Moose, the best place to start is the
334 L<Moose::Cookbook>. The recipes on Moose basics will get you up to
335 speed with many of Moose's features quickly. Once you have an idea of
336 what Moose can do, you can use the API documentation to get more
337 detail on features which interest you.
339 =head2 Moose Extensions
341 The C<MooseX::> namespace is the official place to find Moose extensions.
342 These extensions can be found on the CPAN. The easiest way to find them
343 is to search for them (L<http://search.cpan.org/search?query=MooseX::>),
344 or to examine L<Task::Moose> which aims to keep an up-to-date, easily
345 installable list of Moose extensions.
347 =head1 BUILDING CLASSES WITH MOOSE
349 Moose makes every attempt to provide as much convenience as possible during
350 class construction/definition, but still stay out of your way if you want it
351 to. Here are a few items to note when building classes with Moose.
353 Unless specified with C<extends>, any class which uses Moose will
354 inherit from L<Moose::Object>.
356 Moose will also manage all attributes (including inherited ones) that are
357 defined with C<has>. And (assuming you call C<new>, which is inherited from
358 L<Moose::Object>) this includes properly initializing all instance slots,
359 setting defaults where appropriate, and performing any type constraint checking
362 =head1 PROVIDED METHODS
364 Moose provides a number of methods to all your classes, mostly through the
365 inheritance of L<Moose::Object>. There is however, one exception.
371 This is a method which provides access to the current class's metaclass.
375 =head1 EXPORTED FUNCTIONS
377 Moose will export a number of functions into the class's namespace which
378 may then be used to set up the class. These functions all work directly
379 on the current class.
383 =item B<extends (@superclasses)>
385 This function will set the superclass(es) for the current class.
387 This approach is recommended instead of C<use base>, because C<use base>
388 actually C<push>es onto the class's C<@ISA>, whereas C<extends> will
389 replace it. This is important to ensure that classes which do not have
390 superclasses still properly inherit from L<Moose::Object>.
392 =item B<with (@roles)>
394 This will apply a given set of C<@roles> to the local class.
396 =item B<has $name =E<gt> %options>
398 This will install an attribute of a given C<$name> into the current class.
399 The C<%options> are the same as those provided by
400 L<Class::MOP::Attribute>, in addition to the list below which are provided
401 by Moose (L<Moose::Meta::Attribute> to be more specific):
405 =item I<is =E<gt> 'rw'|'ro'>
407 The I<is> option accepts either I<rw> (for read/write) or I<ro> (for read
408 only). These will create either a read/write accessor or a read-only
409 accessor respectively, using the same name as the C<$name> of the attribute.
411 If you need more control over how your accessors are named, you can use the
412 I<reader>, I<writer> and I<accessor> options inherited from
413 L<Class::MOP::Attribute>, however if you use those, you won't need the I<is>
416 =item I<isa =E<gt> $type_name>
418 The I<isa> option uses Moose's type constraint facilities to set up runtime
419 type checking for this attribute. Moose will perform the checks during class
420 construction, and within any accessors. The C<$type_name> argument must be a
421 string. The string may be either a class name or a type defined using
422 Moose's type definition features. (Refer to L<Moose::Util::TypeConstraints>
423 for information on how to define a new type, and how to retrieve type meta-data).
425 =item I<coerce =E<gt> (1|0)>
427 This will attempt to use coercion with the supplied type constraint to change
428 the value passed into any accessors or constructors. You B<must> have supplied
429 a type constraint in order for this to work. See L<Moose::Cookbook::Basics::Recipe5>
432 =item I<does =E<gt> $role_name>
434 This will accept the name of a role which the value stored in this attribute
435 is expected to have consumed.
437 =item I<required =E<gt> (1|0)>
439 This marks the attribute as being required. This means a I<defined> value must be
440 supplied during class construction, and the attribute may never be set to
441 C<undef> with an accessor.
443 =item I<weak_ref =E<gt> (1|0)>
445 This will tell the class to store the value of this attribute as a weakened
446 reference. If an attribute is a weakened reference, it B<cannot> also be
449 =item I<lazy =E<gt> (1|0)>
451 This will tell the class to not create this slot until absolutely necessary.
452 If an attribute is marked as lazy it B<must> have a default supplied.
454 =item I<auto_deref =E<gt> (1|0)>
456 This tells the accessor whether to automatically dereference the value returned.
457 This is only legal if your C<isa> option is either C<ArrayRef> or C<HashRef>.
459 =item I<trigger =E<gt> $code>
461 The I<trigger> option is a CODE reference which will be called after the value of
462 the attribute is set. The CODE ref will be passed the instance itself, the
463 updated value and the attribute meta-object (this is for more advanced fiddling
464 and can typically be ignored). You B<cannot> have a trigger on a read-only
467 =item I<handles =E<gt> ARRAY | HASH | REGEXP | ROLE | CODE>
469 The I<handles> option provides Moose classes with automated delegation features.
470 This is a pretty complex and powerful option. It accepts many different option
471 formats, each with its own benefits and drawbacks.
473 B<NOTE:> The class being delegated to does not need to be a Moose based class,
474 which is why this feature is especially useful when wrapping non-Moose classes.
476 All I<handles> option formats share the following traits:
478 You cannot override a locally defined method with a delegated method; an
479 exception will be thrown if you try. That is to say, if you define C<foo> in
480 your class, you cannot override it with a delegated C<foo>. This is almost never
481 something you would want to do, and if it is, you should do it by hand and not
484 You cannot override any of the methods found in Moose::Object, or the C<BUILD>
485 and C<DEMOLISH> methods. These will not throw an exception, but will silently
486 move on to the next method in the list. My reasoning for this is that you would
487 almost never want to do this, since it usually breaks your class. As with
488 overriding locally defined methods, if you do want to do this, you should do it
489 manually, not with Moose.
491 You do not I<need> to have a reader (or accessor) for the attribute in order
492 to delegate to it. Moose will create a means of accessing the value for you,
493 however this will be several times B<less> efficient then if you had given
494 the attribute a reader (or accessor) to use.
496 Below is the documentation for each option format:
502 This is the most common usage for I<handles>. You basically pass a list of
503 method names to be delegated, and Moose will install a delegation method
508 This is the second most common usage for I<handles>. Instead of a list of
509 method names, you pass a HASH ref where each key is the method name you
510 want installed locally, and its value is the name of the original method
511 in the class being delegated to.
513 This can be very useful for recursive classes like trees. Here is a
514 quick example (soon to be expanded into a Moose::Cookbook recipe):
519 has 'node' => (is => 'rw', isa => 'Any');
524 default => sub { [] }
532 parent_node => 'node',
533 siblings => 'children',
537 In this example, the Tree package gets C<parent_node> and C<siblings> methods,
538 which delegate to the C<node> and C<children> methods (respectively) of the Tree
539 instance stored in the C<parent> slot.
543 The regexp option works very similar to the ARRAY option, except that it builds
544 the list of methods for you. It starts by collecting all possible methods of the
545 class being delegated to, then filters that list using the regexp supplied here.
547 B<NOTE:> An I<isa> option is required when using the regexp option format. This
548 is so that we can determine (at compile time) the method list from the class.
549 Without an I<isa> this is just not possible.
553 With the role option, you specify the name of a role whose "interface" then
554 becomes the list of methods to handle. The "interface" can be defined as; the
555 methods of the role and any required methods of the role. It should be noted
556 that this does B<not> include any method modifiers or generated attribute
557 methods (which is consistent with role composition).
561 This is the option to use when you really want to do something funky. You should
562 only use it if you really know what you are doing, as it involves manual
565 This takes a code reference, which should expect two arguments. The first is the
566 attribute meta-object this I<handles> is attached to. The second is the
567 metaclass of the class being delegated to. It expects you to return a hash (not
568 a HASH ref) of the methods you want mapped.
572 =item I<metaclass =E<gt> $metaclass_name>
574 This tells the class to use a custom attribute metaclass for this particular
575 attribute. Custom attribute metaclasses are useful for extending the
576 capabilities of the I<has> keyword: they are the simplest way to extend the MOP,
577 but they are still a fairly advanced topic and too much to cover here, see
578 L<Moose::Cookbook::Meta::Recipe1> for more information.
580 The default behavior here is to just load C<$metaclass_name>; however, we also
581 have a way to alias to a shorter name. This will first look to see if
582 B<Moose::Meta::Attribute::Custom::$metaclass_name> exists. If it does, Moose
583 will then check to see if that has the method C<register_implementation>, which
584 should return the actual name of the custom attribute metaclass. If there is no
585 C<register_implementation> method, it will fall back to using
586 B<Moose::Meta::Attribute::Custom::$metaclass_name> as the metaclass name.
588 =item I<traits =E<gt> [ @role_names ]>
590 This tells Moose to take the list of C<@role_names> and apply them to the
591 attribute meta-object. This is very similar to the I<metaclass> option, but
592 allows you to use more than one extension at a time.
594 See L<TRAIT NAME RESOLUTION> for details on how a trait name is
595 resolved to a class name.
597 Also see L<Moose::Cookbook::Meta::Recipe3> for a metaclass trait
602 =item B<has +$name =E<gt> %options>
604 This is variation on the normal attibute creator C<has> which allows you to
605 clone and extend an attribute from a superclass or from a role. Here is an
606 example of the superclass usage:
614 default => 'Hello, I am a Foo'
622 has '+message' => (default => 'Hello I am My::Foo');
624 What is happening here is that B<My::Foo> is cloning the C<message> attribute
625 from its parent class B<Foo>, retaining the C<is =E<gt> 'rw'> and C<isa =E<gt>
626 'Str'> characteristics, but changing the value in C<default>.
628 Here is another example, but within the context of a role:
636 default => 'Hello, I am a Foo'
644 has '+message' => (default => 'Hello I am My::Foo');
646 In this case, we are basically taking the attribute which the role supplied
647 and altering it within the bounds of this feature.
649 Aside from where the attributes come from (one from superclass, the other
650 from a role), this feature works exactly the same. This feature is restricted
651 somewhat, so as to try and force at least I<some> sanity into it. You are only
652 allowed to change the following attributes:
658 Change the default value of an attribute.
662 Change whether the attribute attempts to coerce a value passed to it.
666 Change if the attribute is required to have a value.
668 =item I<documentation>
670 Change the documentation string associated with the attribute.
674 Change if the attribute lazily initializes the slot.
678 You I<are> allowed to change the type without restriction.
680 It is recommended that you use this freedom with caution. We used to
681 only allow for extension only if the type was a subtype of the parent's
682 type, but we felt that was too restrictive and is better left as a
687 You are allowed to B<add> a new C<handles> definition, but you are B<not>
688 allowed to I<change> one.
692 You are allowed to B<add> a new C<builder> definition, but you are B<not>
693 allowed to I<change> one.
697 You are allowed to B<add> a new C<metaclass> definition, but you are
698 B<not> allowed to I<change> one.
702 You are allowed to B<add> additional traits to the C<traits> definition.
703 These traits will be composed into the attribute, but pre-existing traits
704 B<are not> overridden, or removed.
708 =item B<before $name|@names =E<gt> sub { ... }>
710 =item B<after $name|@names =E<gt> sub { ... }>
712 =item B<around $name|@names =E<gt> sub { ... }>
714 This three items are syntactic sugar for the before, after, and around method
715 modifier features that L<Class::MOP> provides. More information on these may be
716 found in the L<Class::MOP::Class documentation|Class::MOP::Class/"Method
721 The keyword C<super> is a no-op when called outside of an C<override> method. In
722 the context of an C<override> method, it will call the next most appropriate
723 superclass method with the same arguments as the original method.
725 =item B<override ($name, &sub)>
727 An C<override> method is a way of explicitly saying "I am overriding this
728 method from my superclass". You can call C<super> within this method, and
729 it will work as expected. The same thing I<can> be accomplished with a normal
730 method call and the C<SUPER::> pseudo-package; it is really your choice.
734 The keyword C<inner>, much like C<super>, is a no-op outside of the context of
735 an C<augment> method. You can think of C<inner> as being the inverse of
736 C<super>; the details of how C<inner> and C<augment> work is best described in
737 the L<Moose::Cookbook::Basics::Recipe6>.
739 =item B<augment ($name, &sub)>
741 An C<augment> method, is a way of explicitly saying "I am augmenting this
742 method from my superclass". Once again, the details of how C<inner> and
743 C<augment> work is best described in the L<Moose::Cookbook::Basics::Recipe6>.
747 This is the C<Carp::confess> function, and exported here because I use it
752 This is the C<Scalar::Util::blessed> function, it is exported here because I
753 use it all the time. It is highly recommended that this is used instead of
754 C<ref> anywhere you need to test for an object's class name.
758 =head1 METACLASS TRAITS
760 When you use Moose, you can also specify traits which will be applied
763 use Moose -traits => 'My::Trait';
765 This is very similar to the attribute traits feature. When you do
766 this, your class's C<meta> object will have the specified traits
767 applied to it. See L<TRAIT NAME RESOLUTION> for more details.
769 =head1 TRAIT NAME RESOLUTION
771 By default, when given a trait name, Moose simply tries to load a
772 class of the same name. If such a class does not exist, it then looks
773 for for a class matching
774 B<Moose::Meta::$type::Custom::Trait::$trait_name>. The C<$type>
775 variable here will be one of B<Attribute> or B<Class>, depending on
776 what the trait is being applied to.
778 If a class with this long name exists, Moose checks to see if it has
779 the method C<register_implementation>. This method is expected to
780 return the I<real> class name of the trait. If there is no
781 C<register_implementation> method, it will fall back to using
782 B<Moose::Meta::$type::Custom::Trait::$trait> as the trait name.
784 If all this is confusing, take a look at
785 L<Moose::Cookbook::Meta::Recipe3>, which demonstrates how to create an
788 =head1 UNIMPORTING FUNCTIONS
792 Moose offers a way to remove the keywords it exports, through the C<unimport>
793 method. You simply have to say C<no Moose> at the bottom of your code for this
794 to work. Here is an example:
799 has 'first_name' => (is => 'rw', isa => 'Str');
800 has 'last_name' => (is => 'rw', isa => 'Str');
804 $self->first_name . ' ' . $self->last_name
807 no Moose; # keywords are removed from the Person package
809 =head1 EXTENDING AND EMBEDDING MOOSE
811 Moose also offers some options for extending or embedding it into your
812 own framework. There are several things you might want to do as part
813 of such a framework. First, you probably want to export Moose's sugar
814 functions (C<has>, C<extends>, etc) for users of the
815 framework. Second, you may want to provide additional sugar of your
816 own. Third, you may want to provide your own object base class instead
817 of L<Moose::Object>, and/or your own metaclass class instead of
818 L<Moose::Meta::Class>.
820 The exporting needs can be asily satisfied by using
821 L<Moose::Exporter>, which is what C<Moose.pm> itself uses for
822 exporting. L<Moose::Exporter> lets you "export like Moose".
824 If you define an C<init_meta> method in a module that uses
825 L<Moose::Exporter>, then this method will be called I<before>
826 C<Moose.pm>'s own C<init_meta>. This gives you a chance to provide an
827 alternate object base class or metaclass class.
829 Here is a simple example:
836 use Moose (); # no need to get Moose's exports
839 Moose::Exporter->setup_import_methods( also => 'Moose' );
843 return Moose->init_meta( @_, base_class => 'MyFramework::Base' );
846 In this example, any class that includes C<use MyFramework> will get
847 all of C<Moose.pm>'s sugar functions, and will have their superclass
848 set to C<MyFramework::Base>.
850 Additionally, that class can include C<no MyFramework> to unimport
852 =head2 B<< Moose->init_meta(for_class => $class, base_class => $baseclass, metaclass => $metaclass) >>
854 The C<init_meta> method sets up the metaclass object for the class
855 specified by C<for_class>. This method injects a a C<meta> accessor
856 into the class so you can get at this object. It also sets the class's
857 superclass to C<base_class>, with L<Moose::Object> as the default.
859 You can specify an alternate metaclass with the C<metaclass> parameter.
861 For more detail on this topic, see L<Moose::Cookbook::Extending::Recipe2>.
863 This method used to be documented as a function which accepted
864 positional parameters. This calling style will still work for
865 backwards compatibility, but is deprecated.
869 Moose's C<import> method supports the L<Sub::Exporter> form of C<{into =E<gt> $pkg}>
870 and C<{into_level =E<gt> 1}>.
872 B<NOTE>: Doing this is more or less deprecated. Use L<Moose::Exporter>
873 instead, which lets you stack multiple C<Moose.pm>-alike modules
874 sanely. It handles getting the exported functions into the right place
883 It should be noted that C<super> and C<inner> B<cannot> be used in the same
884 method. However, they may be combined within the same class hierarchy; see
885 F<t/014_override_augment_inner_super.t> for an example.
887 The reason for this is that C<super> is only valid within a method
888 with the C<override> modifier, and C<inner> will never be valid within an
889 C<override> method. In fact, C<augment> will skip over any C<override> methods
890 when searching for its appropriate C<inner>.
892 This might seem like a restriction, but I am of the opinion that keeping these
893 two features separate (yet interoperable) actually makes them easy to use, since
894 their behavior is then easier to predict. Time will tell whether I am right or
895 not (UPDATE: so far so good).
899 It is important to note that we currently have no simple way of combining
900 multiple extended versions of Moose (see L<EXTENDING AND EMBEDDING MOOSE> above),
901 and that in many cases they will conflict with one another. We are working on
902 developing a way around this issue, but in the meantime, you have been warned.
908 In case you are still asking yourself "Why do I need this?", then this
909 section is for you. This used to be part of the main DESCRIPTION, but
910 I think Moose no longer actually needs justification, so it is included
911 (read: buried) here for those who are still not convinced.
915 =item Another object system!?!?
917 Yes, I know there has been an explosion recently of new ways to
918 build objects in Perl 5, most of them based on inside-out objects
919 and other such things. Moose is different because it is not a new
920 object system for Perl 5, but instead an extension of the existing
923 Moose is built on top of L<Class::MOP>, which is a metaclass system
924 for Perl 5. This means that Moose not only makes building normal
925 Perl 5 objects better, but it also provides the power of metaclass
928 =item Is this for real? Or is this just an experiment?
930 Moose is I<based> on the prototypes and experiments I did for the Perl 6
931 meta-model. However, Moose is B<NOT> an experiment/prototype; it is for B<real>.
933 =item Is this ready for use in production?
935 Yes, I believe that it is.
937 Moose has been used successfully in production environemnts by several people
938 and companies (including the one I work for). There are Moose applications
939 which have been in production with little or no issue now for well over two years.
940 I consider it highly stable and we are commited to keeping it stable.
942 Of course, in the end, you need to make this call yourself. If you have
943 any questions or concerns, please feel free to email me, or even the list
944 or just stop by #moose and ask away.
946 =item Is Moose just Perl 6 in Perl 5?
948 No. While Moose is very much inspired by Perl 6, it is not itself Perl 6.
949 Instead, it is an OO system for Perl 5. I built Moose because I was tired of
950 writing the same old boring Perl 5 OO code, and drooling over Perl 6 OO. So
951 instead of switching to Ruby, I wrote Moose :)
953 =item Wait, I<post> modern, I thought it was just I<modern>?
955 So I was reading Larry Wall's talk from the 1999 Linux World entitled
956 "Perl, the first postmodern computer language" in which he talks about how
957 he picked the features for Perl because he thought they were cool and he
958 threw out the ones that he thought sucked. This got me thinking about how
959 we have done the same thing in Moose. For Moose, we have "borrowed" features
960 from Perl 6, CLOS (LISP), Smalltalk, Java, BETA, OCaml, Ruby and more, and
961 the bits we didn't like (cause they sucked) we tossed aside. So for this
962 reason (and a few others) I have re-dubbed Moose a I<postmodern> object system.
968 =head1 ACKNOWLEDGEMENTS
972 =item I blame Sam Vilain for introducing me to the insanity that is meta-models.
974 =item I blame Audrey Tang for then encouraging my meta-model habit in #perl6.
976 =item Without Yuval "nothingmuch" Kogman this module would not be possible,
977 and it certainly wouldn't have this name ;P
979 =item The basis of the TypeContraints module was Rob Kinyon's idea
980 originally, I just ran with it.
982 =item Thanks to mst & chansen and the whole #moose posse for all the
983 early ideas/feature-requests/encouragement/bug-finding.
985 =item Thanks to David "Theory" Wheeler for meta-discussions and spelling fixes.
993 =item L<http://www.iinteractive.com/moose>
995 This is the official web home of Moose, it contains links to our public SVN repo
996 as well as links to a number of talks and articles on Moose and Moose related
999 =item L<Moose::Cookbook> - How to cook a Moose
1001 =item The Moose is flying, a tutorial by Randal Schwartz
1003 Part 1 - L<http://www.stonehenge.com/merlyn/LinuxMag/col94.html>
1005 Part 2 - L<http://www.stonehenge.com/merlyn/LinuxMag/col95.html>
1007 =item L<Class::MOP> documentation
1009 =item The #moose channel on irc.perl.org
1011 =item The Moose mailing list - moose@perl.org
1013 =item Moose stats on ohloh.net - L<http://www.ohloh.net/projects/moose>
1015 =item Several Moose extension modules in the C<MooseX::> namespace.
1017 See L<http://search.cpan.org/search?query=MooseX::> for extensions.
1025 =item The Art of the MetaObject Protocol
1027 I mention this in the L<Class::MOP> docs too, this book was critical in
1028 the development of both modules and is highly recommended.
1036 =item L<http://www.cs.utah.edu/plt/publications/oopsla04-gff.pdf>
1038 This paper (suggested by lbr on #moose) was what lead to the implementation
1039 of the C<super>/C<override> and C<inner>/C<augment> features. If you really
1040 want to understand them, I suggest you read this.
1046 All complex software has bugs lurking in it, and this module is no
1047 exception. If you find a bug please either email me, or add the bug
1050 =head1 FEATURE REQUESTS
1052 We are very strict about what features we add to the Moose core, especially
1053 the user-visible features. Instead we have made sure that the underlying
1054 meta-system of Moose is as extensible as possible so that you can add your
1055 own features easily. That said, occasionally there is a feature needed in the
1056 meta-system to support your planned extension, in which case you should
1057 either email the mailing list or join us on irc at #moose to discuss.
1061 Stevan Little E<lt>stevan@iinteractive.comE<gt>
1063 B<with contributions from:>
1067 Adam (Alias) Kennedy
1069 Anders (Debolaz) Nor Berle
1071 Nathan (kolibre) Gray
1073 Christian (chansen) Hansen
1075 Hans Dieter (confound) Pearcey
1077 Eric (ewilhelm) Wilhelm
1079 Guillermo (groditi) Roditi
1081 Jess (castaway) Robinson
1085 Robert (phaylon) Sedlacek
1089 Scott (konobi) McWhirter
1091 Shlomi (rindolf) Fish
1093 Yuval (nothingmuch) Kogman
1095 Chris (perigrin) Prather
1097 Wallace (wreis) Reis
1099 Jonathan (jrockway) Rockway
1101 Piotr (dexter) Roszatycki
1103 Sam (mugwump) Vilain
1105 Shawn (sartak) Moore
1107 ... and many other #moose folks
1109 =head1 COPYRIGHT AND LICENSE
1111 Copyright 2006-2008 by Infinity Interactive, Inc.
1113 L<http://www.iinteractive.com>
1115 This library is free software; you can redistribute it and/or modify
1116 it under the same terms as Perl itself.