8 our $AUTHORITY = 'cpan:STEVAN';
10 use Scalar::Util 'blessed', 'reftype';
12 use Sub::Name 'subname';
13 use B 'svref_2object';
19 use Moose::Meta::Class;
20 use Moose::Meta::TypeConstraint;
21 use Moose::Meta::TypeCoercion;
22 use Moose::Meta::Attribute;
23 use Moose::Meta::Instance;
25 use Moose::Meta::Role;
28 use Moose::Util::TypeConstraints;
34 my ( $class, $base_class, $metaclass ) = @_;
35 $base_class = $class unless defined $base_class;
36 $metaclass = 'Moose::Meta::Class' unless defined $metaclass;
39 "The Metaclass $metaclass must be a subclass of Moose::Meta::Class."
40 unless $metaclass->isa('Moose::Meta::Class');
42 # make a subtype for each Moose class
43 subtype $class => as 'Object' => where { $_->isa($class) } =>
44 optimize_as { blessed( $_[0] ) && $_[0]->isa($class) }
45 unless find_type_constraint($class);
48 if ( $class->can('meta') ) {
50 # this is the case where the metaclass pragma
51 # was used before the 'use Moose' statement to
52 # override a specific class
53 $meta = $class->meta();
54 ( blessed($meta) && $meta->isa('Moose::Meta::Class') )
56 "You already have a &meta function, but it does not return a Moose::Meta::Class";
60 # this is broken currently, we actually need
61 # to allow the possiblity of an inherited
62 # meta, which will not be visible until the
63 # user 'extends' first. This needs to have
64 # more intelligence to it
65 $meta = $metaclass->initialize($class);
69 # re-initialize so it inherits properly
70 $metaclass->initialize( blessed( $_[0] ) || $_[0] );
75 # make sure they inherit from Moose::Object
76 $meta->superclasses($base_class)
77 unless $meta->superclasses();
83 return subname 'Moose::extends' => sub (@) {
84 confess "Must derive at least one class" unless @_;
85 Class::MOP::load_class($_) for @_;
87 # this checks the metaclass to make sure
88 # it is correct, sometimes it can get out
89 # of sync when the classes are being built
90 my $meta = $class->meta->_fix_metaclass_incompatability(@_);
91 $meta->superclasses(@_);
96 return subname 'Moose::with' => sub (@) {
98 confess "Must specify at least one role" unless @roles;
99 Class::MOP::load_class($_) for @roles;
100 $class->meta->_apply_all_roles(@roles);
105 return subname 'Moose::has' => sub ($;%) {
106 my ( $name, %options ) = @_;
107 my $attrs = ( ref($name) eq 'ARRAY' ) ? $name : [ ($name) ];
108 $class->meta->_process_attribute( $_, %options ) for @$attrs;
113 return subname 'Moose::before' => sub (@&) {
115 my $meta = $class->meta;
116 $meta->add_before_method_modifier( $_, $code ) for @_;
121 return subname 'Moose::after' => sub (@&) {
123 my $meta = $class->meta;
124 $meta->add_after_method_modifier( $_, $code ) for @_;
129 return subname 'Moose::around' => sub (@&) {
131 my $meta = $class->meta;
132 $meta->add_around_method_modifier( $_, $code ) for @_;
139 $SUPER_SLOT{$CALLER} = \*{"${CALLER}::super"};
141 return subname 'Moose::super' => sub { };
145 return subname 'Moose::override' => sub ($&) {
146 my ( $name, $method ) = @_;
147 $class->meta->add_override_method_modifier( $name => $method );
154 $INNER_SLOT{$CALLER} = \*{"${CALLER}::inner"};
156 return subname 'Moose::inner' => sub { };
160 return subname 'Moose::augment' => sub (@&) {
161 my ( $name, $method ) = @_;
162 $class->meta->add_augment_method_modifier( $name => $method );
167 # this is experimental, but I am not
168 # happy with it. If you want to try
169 # it, you will have to uncomment it
171 # There is a really good chance that
172 # this will be deprecated, dont get
175 # return subname 'Moose::self' => sub {};
178 # my $class = $CALLER;
179 # return subname 'Moose::method' => sub {
180 # my ($name, $method) = @_;
181 # $class->meta->add_method($name, sub {
184 # no warnings 'redefine';
185 # local *{$class->meta->name . '::self'} = sub { $self };
192 return \&Carp::confess;
195 return \&Scalar::Util::blessed;
199 my $exporter = Sub::Exporter::build_exporter(
201 exports => \%exports,
202 groups => { default => [':all'] }
208 ref $_[1] && defined $_[1]->{into} ? $_[1]->{into}
210 && defined $_[1]->{into_level} ? caller( $_[1]->{into_level} )
215 # we should never export to main
216 return if $CALLER eq 'main';
218 init_meta( $CALLER, 'Moose::Object' );
225 my $class = caller();
227 # loop through the exports ...
228 foreach my $name ( keys %exports ) {
231 if ( defined &{ $class . '::' . $name } ) {
232 my $keyword = \&{ $class . '::' . $name };
234 # make sure it is from Moose
236 eval { svref_2object($keyword)->GV->STASH->NAME };
238 next if $pkg_name ne 'Moose';
240 # and if it is from Moose then undef the slot
241 delete ${ $class . '::' }{$name};
248 ## make 'em all immutable
250 $_->meta->make_immutable(
251 inline_constructor => 0,
252 inline_accessors => 1,
255 'Moose::Meta::Attribute',
256 'Moose::Meta::Class',
257 'Moose::Meta::Instance',
259 'Moose::Meta::TypeConstraint',
260 'Moose::Meta::TypeConstraint::Union',
261 'Moose::Meta::TypeConstraint::Container',
262 'Moose::Meta::TypeCoercion',
264 'Moose::Meta::Method',
265 'Moose::Meta::Method::Accessor',
266 'Moose::Meta::Method::Constructor',
267 'Moose::Meta::Method::Destructor',
268 'Moose::Meta::Method::Overriden',
271 'Moose::Meta::Role::Method',
272 'Moose::Meta::Role::Method::Required',
283 Moose - A complete modern object system for Perl 5
288 use Moose; # automatically turns on strict and warnings
290 has 'x' => (is => 'rw', isa => 'Int');
291 has 'y' => (is => 'rw', isa => 'Int');
304 has 'z' => (is => 'rw', isa => 'Int');
306 after 'clear' => sub {
313 Moose is an extension of the Perl 5 object system.
315 =head2 Another object system!?!?
317 Yes, I know there has been an explosion recently of new ways to
318 build object's in Perl 5, most of them based on inside-out objects
319 and other such things. Moose is different because it is not a new
320 object system for Perl 5, but instead an extension of the existing
323 Moose is built on top of L<Class::MOP>, which is a metaclass system
324 for Perl 5. This means that Moose not only makes building normal
325 Perl 5 objects better, but it also provides the power of metaclass
328 =head2 Is this for real? Or is this just an experiment?
330 Moose is I<based> on the prototypes and experiments I did for the Perl 6
331 meta-model. However, Moose is B<NOT> an experiment/prototype; it is for B<real>.
333 =head2 Is this ready for use in production?
335 Yes, I believe that it is.
337 I have two medium-to-large-ish web applications which use Moose heavily
338 and have been in production (without issue) for several months now. At
339 $work, we are re-writing our core offering in it. And several people on
340 #moose have been using it (in production) for several months now as well.
342 Of course, in the end, you need to make this call yourself. If you have
343 any questions or concerns, please feel free to email me, or even the list
344 or just stop by #moose and ask away.
346 =head2 Is Moose just Perl 6 in Perl 5?
348 No. While Moose is very much inspired by Perl 6, it is not itself Perl 6.
349 Instead, it is an OO system for Perl 5. I built Moose because I was tired of
350 writing the same old boring Perl 5 OO code, and drooling over Perl 6 OO. So
351 instead of switching to Ruby, I wrote Moose :)
353 =head1 BUILDING CLASSES WITH MOOSE
355 Moose makes every attempt to provide as much convenience as possible during
356 class construction/definition, but still stay out of your way if you want it
357 to. Here are a few items to note when building classes with Moose.
359 Unless specified with C<extends>, any class which uses Moose will
360 inherit from L<Moose::Object>.
362 Moose will also manage all attributes (including inherited ones) that are
363 defined with C<has>. And (assuming you call C<new>, which is inherited from
364 L<Moose::Object>) this includes properly initializing all instance slots,
365 setting defaults where appropriate, and performing any type constraint checking
368 =head1 EXPORTED FUNCTIONS
370 Moose will export a number of functions into the class's namespace which
371 may then be used to set up the class. These functions all work directly
372 on the current class.
378 This is a method which provides access to the current class's metaclass.
380 =item B<extends (@superclasses)>
382 This function will set the superclass(es) for the current class.
384 This approach is recommended instead of C<use base>, because C<use base>
385 actually C<push>es onto the class's C<@ISA>, whereas C<extends> will
386 replace it. This is important to ensure that classes which do not have
387 superclasses still properly inherit from L<Moose::Object>.
389 =item B<with (@roles)>
391 This will apply a given set of C<@roles> to the local class. Role support
392 is currently under heavy development; see L<Moose::Role> for more details.
394 =item B<has $name =E<gt> %options>
396 This will install an attribute of a given C<$name> into the current class.
397 The C<%options> are the same as those provided by
398 L<Class::MOP::Attribute>, in addition to the list below which are provided
399 by Moose (L<Moose::Meta::Attribute> to be more specific):
403 =item I<is =E<gt> 'rw'|'ro'>
405 The I<is> option accepts either I<rw> (for read/write) or I<ro> (for read
406 only). These will create either a read/write accessor or a read-only
407 accessor respectively, using the same name as the C<$name> of the attribute.
409 If you need more control over how your accessors are named, you can use the
410 I<reader>, I<writer> and I<accessor> options inherited from
411 L<Class::MOP::Attribute>.
413 =item I<isa =E<gt> $type_name>
415 The I<isa> option uses Moose's type constraint facilities to set up runtime
416 type checking for this attribute. Moose will perform the checks during class
417 construction, and within any accessors. The C<$type_name> argument must be a
418 string. The string may be either a class name or a type defined using
419 Moose's type definition features. (Refer to L<Moose::Util::TypeConstraints>
420 for information on how to define a new type, and how to retrieve type meta-data).
422 =item I<coerce =E<gt> (1|0)>
424 This will attempt to use coercion with the supplied type constraint to change
425 the value passed into any accessors or constructors. You B<must> have supplied
426 a type constraint in order for this to work. See L<Moose::Cookbook::Recipe5>
429 =item I<does =E<gt> $role_name>
431 This will accept the name of a role which the value stored in this attribute
432 is expected to have consumed.
434 =item I<required =E<gt> (1|0)>
436 This marks the attribute as being required. This means a I<defined> value must be
437 supplied during class construction, and the attribute may never be set to
438 C<undef> with an accessor.
440 =item I<weak_ref =E<gt> (1|0)>
442 This will tell the class to store the value of this attribute as a weakened
443 reference. If an attribute is a weakened reference, it B<cannot> also be
446 =item I<lazy =E<gt> (1|0)>
448 This will tell the class to not create this slot until absolutely necessary.
449 If an attribute is marked as lazy it B<must> have a default supplied.
451 =item I<auto_deref =E<gt> (1|0)>
453 This tells the accessor whether to automatically dereference the value returned.
454 This is only legal if your C<isa> option is either C<ArrayRef> or C<HashRef>.
456 =item I<metaclass =E<gt> $metaclass_name>
458 This tells the class to use a custom attribute metaclass for this particular
459 attribute. Custom attribute metaclasses are useful for extending the
460 capabilities of the I<has> keyword: they are the simplest way to extend the MOP,
461 but they are still a fairly advanced topic and too much to cover here. I will
462 try and write a recipe on them soon.
464 The default behavior here is to just load C<$metaclass_name>; however, we also
465 have a way to alias to a shorter name. This will first look to see if
466 B<Moose::Meta::Attribute::Custom::$metaclass_name> exists. If it does, Moose
467 will then check to see if that has the method C<register_implemenetation>, which
468 should return the actual name of the custom attribute metaclass. If there is no
469 C<register_implemenetation> method, it will fall back to using
470 B<Moose::Meta::Attribute::Custom::$metaclass_name> as the metaclass name.
472 =item I<trigger =E<gt> $code>
474 The I<trigger> option is a CODE reference which will be called after the value of
475 the attribute is set. The CODE ref will be passed the instance itself, the
476 updated value and the attribute meta-object (this is for more advanced fiddling
477 and can typically be ignored). You B<cannot> have a trigger on a read-only
480 =item I<handles =E<gt> ARRAY | HASH | REGEXP | ROLE | CODE>
482 The I<handles> option provides Moose classes with automated delegation features.
483 This is a pretty complex and powerful option. It accepts many different option
484 formats, each with its own benefits and drawbacks.
486 B<NOTE:> This feature is no longer experimental, but it may still have subtle
487 bugs lurking in the deeper corners. If you think you have found a bug, you
488 probably have, so please report it to me right away.
490 B<NOTE:> The class being delegated to does not need to be a Moose based class,
491 which is why this feature is especially useful when wrapping non-Moose classes.
493 All I<handles> option formats share the following traits:
495 You cannot override a locally defined method with a delegated method; an
496 exception will be thrown if you try. That is to say, if you define C<foo> in
497 your class, you cannot override it with a delegated C<foo>. This is almost never
498 something you would want to do, and if it is, you should do it by hand and not
501 You cannot override any of the methods found in Moose::Object, or the C<BUILD>
502 and C<DEMOLISH> methods. These will not throw an exception, but will silently
503 move on to the next method in the list. My reasoning for this is that you would
504 almost never want to do this, since it usually breaks your class. As with
505 overriding locally defined methods, if you do want to do this, you should do it
506 manually, not with Moose.
508 Below is the documentation for each option format:
514 This is the most common usage for I<handles>. You basically pass a list of
515 method names to be delegated, and Moose will install a delegation method
520 This is the second most common usage for I<handles>. Instead of a list of
521 method names, you pass a HASH ref where each key is the method name you
522 want installed locally, and its value is the name of the original method
523 in the class being delegated to.
525 This can be very useful for recursive classes like trees. Here is a
526 quick example (soon to be expanded into a Moose::Cookbook::Recipe):
531 has 'node' => (is => 'rw', isa => 'Any');
536 default => sub { [] }
544 parent_node => 'node',
545 siblings => 'children',
549 In this example, the Tree package gets C<parent_node> and C<siblings> methods,
550 which delegate to the C<node> and C<children> methods (respectively) of the Tree
551 instance stored in the C<parent> slot.
555 The regexp option works very similar to the ARRAY option, except that it builds
556 the list of methods for you. It starts by collecting all possible methods of the
557 class being delegated to, then filters that list using the regexp supplied here.
559 B<NOTE:> An I<isa> option is required when using the regexp option format. This
560 is so that we can determine (at compile time) the method list from the class.
561 Without an I<isa> this is just not possible.
565 With the role option, you specify the name of a role whose "interface" then
566 becomes the list of methods to handle. The "interface" can be defined as; the
567 methods of the role and any required methods of the role. It should be noted
568 that this does B<not> include any method modifiers or generated attribute
569 methods (which is consistent with role composition).
573 This is the option to use when you really want to do something funky. You should
574 only use it if you really know what you are doing, as it involves manual
577 This takes a code reference, which should expect two arguments. The first is the
578 attribute meta-object this I<handles> is attached to. The second is the
579 metaclass of the class being delegated to. It expects you to return a hash (not
580 a HASH ref) of the methods you want mapped.
586 =item B<has +$name =E<gt> %options>
588 This is variation on the normal attibute creator C<has> which allows you to
589 clone and extend an attribute from a superclass. Here is a quick example:
597 default => 'Hello, I am a Foo'
605 has '+message' => (default => 'Hello I am My::Foo');
607 What is happening here is that B<My::Foo> is cloning the C<message> attribute
608 from its parent class B<Foo>, retaining the C<is =E<gt> 'rw'> and C<isa =E<gt>
609 'Str'> characteristics, but changing the value in C<default>.
611 This feature is restricted somewhat, so as to try and force at least I<some>
612 sanity into it. You are only allowed to change the following attributes:
618 Change the default value of an attribute.
622 Change whether the attribute attempts to coerce a value passed to it.
626 Change if the attribute is required to have a value.
628 =item I<documentation>
630 Change the documentation string associated with the attribute.
634 Change if the attribute lazily initializes the slot.
638 You I<are> allowed to change the type, B<if and only if> the new type is a
639 subtype of the old type.
643 You are allowed to B<add> a new C<handles> definition, but you are B<not>
644 allowed to I<change> one.
648 =item B<before $name|@names =E<gt> sub { ... }>
650 =item B<after $name|@names =E<gt> sub { ... }>
652 =item B<around $name|@names =E<gt> sub { ... }>
654 This three items are syntactic sugar for the before, after, and around method
655 modifier features that L<Class::MOP> provides. More information on these may be
656 found in the L<Class::MOP::Class documentation|Class::MOP::Class/"Method
661 The keyword C<super> is a no-op when called outside of an C<override> method. In
662 the context of an C<override> method, it will call the next most appropriate
663 superclass method with the same arguments as the original method.
665 =item B<override ($name, &sub)>
667 An C<override> method is a way of explicitly saying "I am overriding this
668 method from my superclass". You can call C<super> within this method, and
669 it will work as expected. The same thing I<can> be accomplished with a normal
670 method call and the C<SUPER::> pseudo-package; it is really your choice.
674 The keyword C<inner>, much like C<super>, is a no-op outside of the context of
675 an C<augment> method. You can think of C<inner> as being the inverse of
676 C<super>; the details of how C<inner> and C<augment> work is best described in
677 the L<Moose::Cookbook>.
679 =item B<augment ($name, &sub)>
681 An C<augment> method, is a way of explicitly saying "I am augmenting this
682 method from my superclass". Once again, the details of how C<inner> and
683 C<augment> work is best described in the L<Moose::Cookbook>.
687 This is the C<Carp::confess> function, and exported here because I use it
688 all the time. This feature may change in the future, so you have been warned.
692 This is the C<Scalar::Util::blessed> function, it is exported here because I
693 use it all the time. It is highly recommended that this is used instead of
694 C<ref> anywhere you need to test for an object's class name.
698 =head1 UNIMPORTING FUNCTIONS
702 Moose offers a way to remove the keywords it exports, through the C<unimport>
703 method. You simply have to say C<no Moose> at the bottom of your code for this
704 to work. Here is an example:
709 has 'first_name' => (is => 'rw', isa => 'Str');
710 has 'last_name' => (is => 'rw', isa => 'Str');
714 $self->first_name . ' ' . $self->last_name
717 no Moose; # keywords are removed from the Person package
719 =head1 EXTENDING AND EMBEDDING MOOSE
721 Moose also offers some options for extending or embedding it into your own
722 framework. The basic premise is to have something that sets up your class'
723 metaclass and export the moose declarators (C<has>, C<with>, C<extends>,...).
730 my $CALLER = caller();
735 # we should never export to main
736 return if $CALLER eq 'main';
737 Moose::init_meta( $CALLER, 'MyFramework::Base' );
738 Moose->import({into => $CALLER});
740 # Do my custom framework stuff
747 Moose's C<import> method supports the Sub::Exporter form of C<{into =E<gt> $pkg}>
748 and C<{into_level =E<gt> 1}>
750 =head2 B<init_meta ($class, $baseclass, $metaclass)>
752 Moose does some boot strapping: it creates a metaclass object for your class,
753 and then injects a C<meta> accessor into your class. Then it sets a baseclass
754 unlesss one is already defined. This is all done via C<init_meta> which takes
755 the name of your class and optionally a baseclass and a metaclass as arguments.
763 It should be noted that C<super> and C<inner> B<cannot> be used in the same
764 method. However, they may be combined within the same class hierarchy; see
765 F<t/014_override_augment_inner_super.t> for an example.
767 The reason for this is that C<super> is only valid within a method
768 with the C<override> modifier, and C<inner> will never be valid within an
769 C<override> method. In fact, C<augment> will skip over any C<override> methods
770 when searching for its appropriate C<inner>.
772 This might seem like a restriction, but I am of the opinion that keeping these
773 two features separate (yet interoperable) actually makes them easy to use, since
774 their behavior is then easier to predict. Time will tell whether I am right or
775 not (UPDATE: so far so good).
779 =head1 ACKNOWLEDGEMENTS
783 =item I blame Sam Vilain for introducing me to the insanity that is meta-models.
785 =item I blame Audrey Tang for then encouraging my meta-model habit in #perl6.
787 =item Without Yuval "nothingmuch" Kogman this module would not be possible,
788 and it certainly wouldn't have this name ;P
790 =item The basis of the TypeContraints module was Rob Kinyon's idea
791 originally, I just ran with it.
793 =item Thanks to mst & chansen and the whole #moose poose for all the
794 early ideas/feature-requests/encouragement/bug-finding.
796 =item Thanks to David "Theory" Wheeler for meta-discussions and spelling fixes.
804 =item L<http://www.iinteractive.com/moose>
806 This is the official web home of Moose, it contains links to our public SVN repo
807 as well as links to a number of talks and articles on Moose and Moose related
810 =item L<Class::MOP> documentation
812 =item The #moose channel on irc.perl.org
814 =item The Moose mailing list - moose@perl.org
816 =item Moose stats on ohloh.net - L<http://www.ohloh.net/projects/5788>
824 =item L<http://www.cs.utah.edu/plt/publications/oopsla04-gff.pdf>
826 This paper (suggested by lbr on #moose) was what lead to the implementation
827 of the C<super>/C<override> and C<inner>/C<augment> features. If you really
828 want to understand them, I suggest you read this.
834 All complex software has bugs lurking in it, and this module is no
835 exception. If you find a bug please either email me, or add the bug
840 Stevan Little E<lt>stevan@iinteractive.comE<gt>
842 B<with contributions from:>
848 Anders (Debolaz) Nor Berle
850 Nathan (kolibre) Gray
852 Christian (chansen) Hansen
854 Eric (ewilhelm) Wilhelm
856 Guillermo (groditi) Roditi
858 Jess (castaway) Robinson
862 Robert (phaylon) Sedlacek
866 Scott (konobi) McWhirter
868 Shlomi (rindolf) Fish
870 Yuval (nothingmuch) Kogman
872 Chris (perigrin) Prather
874 ... and many other #moose folks
876 =head1 COPYRIGHT AND LICENSE
878 Copyright 2006, 2007 by Infinity Interactive, Inc.
880 L<http://www.iinteractive.com>
882 This library is free software; you can redistribute it and/or modify
883 it under the same terms as Perl itself.