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'] }
206 # 1 extra level because it's called by import so there's a layer of indirection
210 ref $_[1] && defined $_[1]->{into}
212 : ref $_[1] && defined $_[1]->{into_level}
213 ? caller($offset + $_[1]->{into_level})
218 $CALLER = _get_caller(@_);
223 # we should never export to main
224 return if $CALLER eq 'main';
226 init_meta( $CALLER, 'Moose::Object' );
233 my $class = _get_caller(@_);
235 # loop through the exports ...
236 foreach my $name ( keys %exports ) {
239 if ( defined &{ $class . '::' . $name } ) {
240 my $keyword = \&{ $class . '::' . $name };
242 # make sure it is from Moose
244 eval { svref_2object($keyword)->GV->STASH->NAME };
246 next if $pkg_name ne 'Moose';
248 # and if it is from Moose then undef the slot
249 delete ${ $class . '::' }{$name};
256 ## make 'em all immutable
258 $_->meta->make_immutable(
259 inline_constructor => 0,
260 inline_accessors => 1, # these are Class::MOP accessors, so they need inlining
263 'Moose::Meta::Attribute',
264 'Moose::Meta::Class',
265 'Moose::Meta::Instance',
267 'Moose::Meta::TypeConstraint',
268 'Moose::Meta::TypeConstraint::Union',
269 'Moose::Meta::TypeConstraint::Parameterized',
270 'Moose::Meta::TypeCoercion',
272 'Moose::Meta::Method',
273 'Moose::Meta::Method::Accessor',
274 'Moose::Meta::Method::Constructor',
275 'Moose::Meta::Method::Destructor',
276 'Moose::Meta::Method::Overriden',
279 'Moose::Meta::Role::Method',
280 'Moose::Meta::Role::Method::Required',
291 Moose - A complete modern object system for Perl 5
296 use Moose; # automatically turns on strict and warnings
298 has 'x' => (is => 'rw', isa => 'Int');
299 has 'y' => (is => 'rw', isa => 'Int');
312 has 'z' => (is => 'rw', isa => 'Int');
314 after 'clear' => sub {
321 Moose is an extension of the Perl 5 object system.
323 =head2 Another object system!?!?
325 Yes, I know there has been an explosion recently of new ways to
326 build object's in Perl 5, most of them based on inside-out objects
327 and other such things. Moose is different because it is not a new
328 object system for Perl 5, but instead an extension of the existing
331 Moose is built on top of L<Class::MOP>, which is a metaclass system
332 for Perl 5. This means that Moose not only makes building normal
333 Perl 5 objects better, but it also provides the power of metaclass
336 =head2 Is this for real? Or is this just an experiment?
338 Moose is I<based> on the prototypes and experiments I did for the Perl 6
339 meta-model. However, Moose is B<NOT> an experiment/prototype; it is for B<real>.
341 =head2 Is this ready for use in production?
343 Yes, I believe that it is.
345 Moose has been used successfully in production environemnts by several people
346 and companies (including the one I work for). There are Moose applications
347 which have been in production with little or no issue now for over a year.
348 I consider it highly stable and we are commited to keeping it stable.
350 Of course, in the end, you need to make this call yourself. If you have
351 any questions or concerns, please feel free to email me, or even the list
352 or just stop by #moose and ask away.
354 =head2 Is Moose just Perl 6 in Perl 5?
356 No. While Moose is very much inspired by Perl 6, it is not itself Perl 6.
357 Instead, it is an OO system for Perl 5. I built Moose because I was tired of
358 writing the same old boring Perl 5 OO code, and drooling over Perl 6 OO. So
359 instead of switching to Ruby, I wrote Moose :)
361 =head1 BUILDING CLASSES WITH MOOSE
363 Moose makes every attempt to provide as much convenience as possible during
364 class construction/definition, but still stay out of your way if you want it
365 to. Here are a few items to note when building classes with Moose.
367 Unless specified with C<extends>, any class which uses Moose will
368 inherit from L<Moose::Object>.
370 Moose will also manage all attributes (including inherited ones) that are
371 defined with C<has>. And (assuming you call C<new>, which is inherited from
372 L<Moose::Object>) this includes properly initializing all instance slots,
373 setting defaults where appropriate, and performing any type constraint checking
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.
386 This is a method which provides access to the current class's metaclass.
388 =item B<extends (@superclasses)>
390 This function will set the superclass(es) for the current class.
392 This approach is recommended instead of C<use base>, because C<use base>
393 actually C<push>es onto the class's C<@ISA>, whereas C<extends> will
394 replace it. This is important to ensure that classes which do not have
395 superclasses still properly inherit from L<Moose::Object>.
397 =item B<with (@roles)>
399 This will apply a given set of C<@roles> to the local class. Role support
400 is currently under heavy development; see L<Moose::Role> for more details.
402 =item B<has $name =E<gt> %options>
404 This will install an attribute of a given C<$name> into the current class.
405 The C<%options> are the same as those provided by
406 L<Class::MOP::Attribute>, in addition to the list below which are provided
407 by Moose (L<Moose::Meta::Attribute> to be more specific):
411 =item I<is =E<gt> 'rw'|'ro'>
413 The I<is> option accepts either I<rw> (for read/write) or I<ro> (for read
414 only). These will create either a read/write accessor or a read-only
415 accessor respectively, using the same name as the C<$name> of the attribute.
417 If you need more control over how your accessors are named, you can use the
418 I<reader>, I<writer> and I<accessor> options inherited from
419 L<Class::MOP::Attribute>.
421 =item I<isa =E<gt> $type_name>
423 The I<isa> option uses Moose's type constraint facilities to set up runtime
424 type checking for this attribute. Moose will perform the checks during class
425 construction, and within any accessors. The C<$type_name> argument must be a
426 string. The string may be either a class name or a type defined using
427 Moose's type definition features. (Refer to L<Moose::Util::TypeConstraints>
428 for information on how to define a new type, and how to retrieve type meta-data).
430 =item I<coerce =E<gt> (1|0)>
432 This will attempt to use coercion with the supplied type constraint to change
433 the value passed into any accessors or constructors. You B<must> have supplied
434 a type constraint in order for this to work. See L<Moose::Cookbook::Recipe5>
437 =item I<does =E<gt> $role_name>
439 This will accept the name of a role which the value stored in this attribute
440 is expected to have consumed.
442 =item I<required =E<gt> (1|0)>
444 This marks the attribute as being required. This means a I<defined> value must be
445 supplied during class construction, and the attribute may never be set to
446 C<undef> with an accessor.
448 =item I<weak_ref =E<gt> (1|0)>
450 This will tell the class to store the value of this attribute as a weakened
451 reference. If an attribute is a weakened reference, it B<cannot> also be
454 =item I<lazy =E<gt> (1|0)>
456 This will tell the class to not create this slot until absolutely necessary.
457 If an attribute is marked as lazy it B<must> have a default supplied.
459 =item I<auto_deref =E<gt> (1|0)>
461 This tells the accessor whether to automatically dereference the value returned.
462 This is only legal if your C<isa> option is either C<ArrayRef> or C<HashRef>.
464 =item I<metaclass =E<gt> $metaclass_name>
466 This tells the class to use a custom attribute metaclass for this particular
467 attribute. Custom attribute metaclasses are useful for extending the
468 capabilities of the I<has> keyword: they are the simplest way to extend the MOP,
469 but they are still a fairly advanced topic and too much to cover here. I will
470 try and write a recipe on them soon.
472 The default behavior here is to just load C<$metaclass_name>; however, we also
473 have a way to alias to a shorter name. This will first look to see if
474 B<Moose::Meta::Attribute::Custom::$metaclass_name> exists. If it does, Moose
475 will then check to see if that has the method C<register_implemenetation>, which
476 should return the actual name of the custom attribute metaclass. If there is no
477 C<register_implemenetation> method, it will fall back to using
478 B<Moose::Meta::Attribute::Custom::$metaclass_name> as the metaclass name.
480 =item I<trigger =E<gt> $code>
482 The I<trigger> option is a CODE reference which will be called after the value of
483 the attribute is set. The CODE ref will be passed the instance itself, the
484 updated value and the attribute meta-object (this is for more advanced fiddling
485 and can typically be ignored). You B<cannot> have a trigger on a read-only
488 =item I<handles =E<gt> ARRAY | HASH | REGEXP | ROLE | CODE>
490 The I<handles> option provides Moose classes with automated delegation features.
491 This is a pretty complex and powerful option. It accepts many different option
492 formats, each with its own benefits and drawbacks.
494 B<NOTE:> This feature is no longer experimental, but it may still have subtle
495 bugs lurking in the deeper corners. If you think you have found a bug, you
496 probably have, so please report it to me right away.
498 B<NOTE:> The class being delegated to does not need to be a Moose based class,
499 which is why this feature is especially useful when wrapping non-Moose classes.
501 All I<handles> option formats share the following traits:
503 You cannot override a locally defined method with a delegated method; an
504 exception will be thrown if you try. That is to say, if you define C<foo> in
505 your class, you cannot override it with a delegated C<foo>. This is almost never
506 something you would want to do, and if it is, you should do it by hand and not
509 You cannot override any of the methods found in Moose::Object, or the C<BUILD>
510 and C<DEMOLISH> methods. These will not throw an exception, but will silently
511 move on to the next method in the list. My reasoning for this is that you would
512 almost never want to do this, since it usually breaks your class. As with
513 overriding locally defined methods, if you do want to do this, you should do it
514 manually, not with Moose.
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.
594 =item B<has +$name =E<gt> %options>
596 This is variation on the normal attibute creator C<has> which allows you to
597 clone and extend an attribute from a superclass. Here is a quick example:
605 default => 'Hello, I am a Foo'
613 has '+message' => (default => 'Hello I am My::Foo');
615 What is happening here is that B<My::Foo> is cloning the C<message> attribute
616 from its parent class B<Foo>, retaining the C<is =E<gt> 'rw'> and C<isa =E<gt>
617 'Str'> characteristics, but changing the value in C<default>.
619 This feature is restricted somewhat, so as to try and force at least I<some>
620 sanity into it. You are only allowed to change the following attributes:
626 Change the default value of an attribute.
630 Change whether the attribute attempts to coerce a value passed to it.
634 Change if the attribute is required to have a value.
636 =item I<documentation>
638 Change the documentation string associated with the attribute.
642 Change if the attribute lazily initializes the slot.
646 You I<are> allowed to change the type, B<if and only if> the new type is a
647 subtype of the old type.
651 You are allowed to B<add> a new C<handles> definition, but you are B<not>
652 allowed to I<change> one.
656 =item B<before $name|@names =E<gt> sub { ... }>
658 =item B<after $name|@names =E<gt> sub { ... }>
660 =item B<around $name|@names =E<gt> sub { ... }>
662 This three items are syntactic sugar for the before, after, and around method
663 modifier features that L<Class::MOP> provides. More information on these may be
664 found in the L<Class::MOP::Class documentation|Class::MOP::Class/"Method
669 The keyword C<super> is a no-op when called outside of an C<override> method. In
670 the context of an C<override> method, it will call the next most appropriate
671 superclass method with the same arguments as the original method.
673 =item B<override ($name, &sub)>
675 An C<override> method is a way of explicitly saying "I am overriding this
676 method from my superclass". You can call C<super> within this method, and
677 it will work as expected. The same thing I<can> be accomplished with a normal
678 method call and the C<SUPER::> pseudo-package; it is really your choice.
682 The keyword C<inner>, much like C<super>, is a no-op outside of the context of
683 an C<augment> method. You can think of C<inner> as being the inverse of
684 C<super>; the details of how C<inner> and C<augment> work is best described in
685 the L<Moose::Cookbook>.
687 =item B<augment ($name, &sub)>
689 An C<augment> method, is a way of explicitly saying "I am augmenting this
690 method from my superclass". Once again, the details of how C<inner> and
691 C<augment> work is best described in the L<Moose::Cookbook>.
695 This is the C<Carp::confess> function, and exported here because I use it
696 all the time. This feature may change in the future, so you have been warned.
700 This is the C<Scalar::Util::blessed> function, it is exported here because I
701 use it all the time. It is highly recommended that this is used instead of
702 C<ref> anywhere you need to test for an object's class name.
706 =head1 UNIMPORTING FUNCTIONS
710 Moose offers a way to remove the keywords it exports, through the C<unimport>
711 method. You simply have to say C<no Moose> at the bottom of your code for this
712 to work. Here is an example:
717 has 'first_name' => (is => 'rw', isa => 'Str');
718 has 'last_name' => (is => 'rw', isa => 'Str');
722 $self->first_name . ' ' . $self->last_name
725 no Moose; # keywords are removed from the Person package
727 =head1 EXTENDING AND EMBEDDING MOOSE
729 Moose also offers some options for extending or embedding it into your own
730 framework. The basic premise is to have something that sets up your class'
731 metaclass and export the moose declarators (C<has>, C<with>, C<extends>,...).
738 my $CALLER = caller();
743 # we should never export to main
744 return if $CALLER eq 'main';
745 Moose::init_meta( $CALLER, 'MyFramework::Base' );
746 Moose->import({into => $CALLER});
748 # Do my custom framework stuff
755 Moose's C<import> method supports the L<Sub::Exporter> form of C<{into =E<gt> $pkg}>
756 and C<{into_level =E<gt> 1}>
758 =head2 B<init_meta ($class, $baseclass, $metaclass)>
760 Moose does some boot strapping: it creates a metaclass object for your class,
761 and then injects a C<meta> accessor into your class to retrieve it. Then it
762 sets your baseclass to Moose::Object or the value you pass in unless you already
763 have one. This is all done via C<init_meta> which takes the name of your class
764 and optionally a baseclass and a metaclass as arguments.
772 It should be noted that C<super> and C<inner> B<cannot> be used in the same
773 method. However, they may be combined within the same class hierarchy; see
774 F<t/014_override_augment_inner_super.t> for an example.
776 The reason for this is that C<super> is only valid within a method
777 with the C<override> modifier, and C<inner> will never be valid within an
778 C<override> method. In fact, C<augment> will skip over any C<override> methods
779 when searching for its appropriate C<inner>.
781 This might seem like a restriction, but I am of the opinion that keeping these
782 two features separate (yet interoperable) actually makes them easy to use, since
783 their behavior is then easier to predict. Time will tell whether I am right or
784 not (UPDATE: so far so good).
788 =head1 ACKNOWLEDGEMENTS
792 =item I blame Sam Vilain for introducing me to the insanity that is meta-models.
794 =item I blame Audrey Tang for then encouraging my meta-model habit in #perl6.
796 =item Without Yuval "nothingmuch" Kogman this module would not be possible,
797 and it certainly wouldn't have this name ;P
799 =item The basis of the TypeContraints module was Rob Kinyon's idea
800 originally, I just ran with it.
802 =item Thanks to mst & chansen and the whole #moose poose for all the
803 early ideas/feature-requests/encouragement/bug-finding.
805 =item Thanks to David "Theory" Wheeler for meta-discussions and spelling fixes.
813 =item L<http://www.iinteractive.com/moose>
815 This is the official web home of Moose, it contains links to our public SVN repo
816 as well as links to a number of talks and articles on Moose and Moose related
819 =item L<Class::MOP> documentation
821 =item The #moose channel on irc.perl.org
823 =item The Moose mailing list - moose@perl.org
825 =item Moose stats on ohloh.net - L<http://www.ohloh.net/projects/5788>
833 =item L<http://www.cs.utah.edu/plt/publications/oopsla04-gff.pdf>
835 This paper (suggested by lbr on #moose) was what lead to the implementation
836 of the C<super>/C<override> and C<inner>/C<augment> features. If you really
837 want to understand them, I suggest you read this.
843 All complex software has bugs lurking in it, and this module is no
844 exception. If you find a bug please either email me, or add the bug
849 Stevan Little E<lt>stevan@iinteractive.comE<gt>
851 B<with contributions from:>
857 Anders (Debolaz) Nor Berle
859 Nathan (kolibre) Gray
861 Christian (chansen) Hansen
863 Hans Dieter (confound) Pearcey
865 Eric (ewilhelm) Wilhelm
867 Guillermo (groditi) Roditi
869 Jess (castaway) Robinson
873 Robert (phaylon) Sedlacek
877 Scott (konobi) McWhirter
879 Shlomi (rindolf) Fish
881 Yuval (nothingmuch) Kogman
883 Chris (perigrin) Prather
885 Jonathan (jrockway) Rockway
887 Piotr (dexter) Roszatycki
891 ... and many other #moose folks
893 =head1 COPYRIGHT AND LICENSE
895 Copyright 2006, 2007 by Infinity Interactive, Inc.
897 L<http://www.iinteractive.com>
899 This library is free software; you can redistribute it and/or modify
900 it under the same terms as Perl itself.