8 our $AUTHORITY = 'cpan:STEVAN';
10 use Scalar::Util 'blessed', 'reftype';
12 use Sub::Name 'subname';
18 use Moose::Meta::Class;
19 use Moose::Meta::TypeConstraint;
20 use Moose::Meta::TypeConstraint::Class;
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;
35 my ( $class, $base_class, $metaclass ) = @_;
36 $base_class = $class unless defined $base_class;
37 $metaclass = 'Moose::Meta::Class' unless defined $metaclass;
40 "The Metaclass $metaclass must be a subclass of Moose::Meta::Class."
41 unless $metaclass->isa('Moose::Meta::Class');
43 # make a subtype for each Moose class
45 unless find_type_constraint($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') )
55 || confess "You already have a &meta function, but it does not return a Moose::Meta::Class";
59 # this is broken currently, we actually need
60 # to allow the possiblity of an inherited
61 # meta, which will not be visible until the
62 # user 'extends' first. This needs to have
63 # more intelligence to it
64 $meta = $metaclass->initialize($class);
67 # re-initialize so it inherits properly
68 $metaclass->initialize( blessed( $_[0] ) || $_[0] );
73 # make sure they inherit from Moose::Object
74 $meta->superclasses($base_class)
75 unless $meta->superclasses();
81 return subname 'Moose::extends' => sub (@) {
82 confess "Must derive at least one class" unless @_;
83 Class::MOP::load_class($_) for @_;
85 # this checks the metaclass to make sure
86 # it is correct, sometimes it can get out
87 # of sync when the classes are being built
88 my $meta = $class->meta->_fix_metaclass_incompatability(@_);
89 $meta->superclasses(@_);
94 return subname 'Moose::with' => sub (@) {
95 Moose::Util::apply_all_roles($class->meta, @_)
100 return subname 'Moose::has' => sub ($;%) {
101 my ( $name, %options ) = @_;
102 my $attrs = ( ref($name) eq 'ARRAY' ) ? $name : [ ($name) ];
103 $class->meta->add_attribute( $_, %options ) for @$attrs;
108 return subname 'Moose::before' => sub (@&) {
110 my $meta = $class->meta;
111 $meta->add_before_method_modifier( $_, $code ) for @_;
116 return subname 'Moose::after' => sub (@&) {
118 my $meta = $class->meta;
119 $meta->add_after_method_modifier( $_, $code ) for @_;
124 return subname 'Moose::around' => sub (@&) {
126 my $meta = $class->meta;
127 $meta->add_around_method_modifier( $_, $code ) for @_;
134 $SUPER_SLOT{$CALLER} = \*{"${CALLER}::super"};
136 return subname 'Moose::super' => sub { };
140 return subname 'Moose::override' => sub ($&) {
141 my ( $name, $method ) = @_;
142 $class->meta->add_override_method_modifier( $name => $method );
149 $INNER_SLOT{$CALLER} = \*{"${CALLER}::inner"};
151 return subname 'Moose::inner' => sub { };
155 return subname 'Moose::augment' => sub (@&) {
156 my ( $name, $method ) = @_;
157 $class->meta->add_augment_method_modifier( $name => $method );
161 return \&Carp::confess;
164 return \&Scalar::Util::blessed;
168 my $exporter = Sub::Exporter::build_exporter(
170 exports => \%exports,
171 groups => { default => [':all'] }
175 # 1 extra level because it's called by import so there's a layer of indirection
179 ref $_[1] && defined $_[1]->{into}
181 : ref $_[1] && defined $_[1]->{into_level}
182 ? caller($offset + $_[1]->{into_level})
187 $CALLER = _get_caller(@_);
192 # we should never export to main
193 return if $CALLER eq 'main';
195 init_meta( $CALLER, 'Moose::Object' );
202 my $class = _get_caller(@_);
204 # loop through the exports ...
205 foreach my $name ( keys %exports ) {
208 if ( defined &{ $class . '::' . $name } ) {
209 my $keyword = \&{ $class . '::' . $name };
211 # make sure it is from Moose
212 my ($pkg_name) = Class::MOP::get_code_info($keyword);
214 next if $pkg_name ne 'Moose';
216 # and if it is from Moose then undef the slot
217 delete ${ $class . '::' }{$name};
224 ## make 'em all immutable
226 $_->meta->make_immutable(
227 inline_constructor => 0,
228 inline_accessors => 1, # these are Class::MOP accessors, so they need inlining
231 'Moose::Meta::Attribute',
232 'Moose::Meta::Class',
233 'Moose::Meta::Instance',
235 'Moose::Meta::TypeConstraint',
236 'Moose::Meta::TypeConstraint::Union',
237 'Moose::Meta::TypeConstraint::Parameterized',
238 'Moose::Meta::TypeCoercion',
240 'Moose::Meta::Method',
241 'Moose::Meta::Method::Accessor',
242 'Moose::Meta::Method::Constructor',
243 'Moose::Meta::Method::Destructor',
244 'Moose::Meta::Method::Overriden',
247 'Moose::Meta::Role::Method',
248 'Moose::Meta::Role::Method::Required',
259 Moose - A postmodern object system for Perl 5
264 use Moose; # automatically turns on strict and warnings
266 has 'x' => (is => 'rw', isa => 'Int');
267 has 'y' => (is => 'rw', isa => 'Int');
280 has 'z' => (is => 'rw', isa => 'Int');
282 after 'clear' => sub {
289 Moose is an extension of the Perl 5 object system.
291 =head2 Another object system!?!?
293 Yes, I know there has been an explosion recently of new ways to
294 build object's in Perl 5, most of them based on inside-out objects
295 and other such things. Moose is different because it is not a new
296 object system for Perl 5, but instead an extension of the existing
299 Moose is built on top of L<Class::MOP>, which is a metaclass system
300 for Perl 5. This means that Moose not only makes building normal
301 Perl 5 objects better, but it also provides the power of metaclass
304 =head2 Is this for real? Or is this just an experiment?
306 Moose is I<based> on the prototypes and experiments I did for the Perl 6
307 meta-model. However, Moose is B<NOT> an experiment/prototype; it is for B<real>.
309 =head2 Is this ready for use in production?
311 Yes, I believe that it is.
313 Moose has been used successfully in production environemnts by several people
314 and companies (including the one I work for). There are Moose applications
315 which have been in production with little or no issue now for well over a year.
316 I consider it highly stable and we are commited to keeping it stable.
318 Of course, in the end, you need to make this call yourself. If you have
319 any questions or concerns, please feel free to email me, or even the list
320 or just stop by #moose and ask away.
322 =head2 Is Moose just Perl 6 in Perl 5?
324 No. While Moose is very much inspired by Perl 6, it is not itself Perl 6.
325 Instead, it is an OO system for Perl 5. I built Moose because I was tired of
326 writing the same old boring Perl 5 OO code, and drooling over Perl 6 OO. So
327 instead of switching to Ruby, I wrote Moose :)
329 =head2 Wait, I<post> modern, I thought it was just I<modern>?
331 So I was reading Larry Wall's talk from the 1999 Linux World entitled
332 "Perl, the first postmodern computer language" in which he talks about how
333 he picked the features for Perl because he thought they were cool and he
334 threw out the ones that he thought sucked. This got me thinking about how
335 we have done the same thing in Moose. For Moose, we have "borrowed" features
336 from Perl 6, CLOS (LISP), Smalltalk, Java, BETA, OCaml, Ruby and more, and
337 the bits we didn't like (cause they sucked) we tossed aside. So for this
338 reason (and a few others) I have re-dubbed Moose a I<postmodern> object system.
342 =head2 Moose Extensions
344 The L<MooseX::> namespace is the official place to find Moose extensions.
345 There are a number of these modules out on CPAN right now the best way to
346 find them is to search for MooseX:: on search.cpan.org.
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 EXPORTED FUNCTIONS
365 Moose will export a number of functions into the class's namespace which
366 may then be used to set up the class. These functions all work directly
367 on the current class.
373 This is a method which provides access to the current class's metaclass.
375 =item B<extends (@superclasses)>
377 This function will set the superclass(es) for the current class.
379 This approach is recommended instead of C<use base>, because C<use base>
380 actually C<push>es onto the class's C<@ISA>, whereas C<extends> will
381 replace it. This is important to ensure that classes which do not have
382 superclasses still properly inherit from L<Moose::Object>.
384 =item B<with (@roles)>
386 This will apply a given set of C<@roles> to the local class. Role support
387 is currently under heavy development; see L<Moose::Role> for more details.
389 =item B<has $name =E<gt> %options>
391 This will install an attribute of a given C<$name> into the current class.
392 The C<%options> are the same as those provided by
393 L<Class::MOP::Attribute>, in addition to the list below which are provided
394 by Moose (L<Moose::Meta::Attribute> to be more specific):
398 =item I<is =E<gt> 'rw'|'ro'>
400 The I<is> option accepts either I<rw> (for read/write) or I<ro> (for read
401 only). These will create either a read/write accessor or a read-only
402 accessor respectively, using the same name as the C<$name> of the attribute.
404 If you need more control over how your accessors are named, you can use the
405 I<reader>, I<writer> and I<accessor> options inherited from
406 L<Class::MOP::Attribute>.
408 =item I<isa =E<gt> $type_name>
410 The I<isa> option uses Moose's type constraint facilities to set up runtime
411 type checking for this attribute. Moose will perform the checks during class
412 construction, and within any accessors. The C<$type_name> argument must be a
413 string. The string may be either a class name or a type defined using
414 Moose's type definition features. (Refer to L<Moose::Util::TypeConstraints>
415 for information on how to define a new type, and how to retrieve type meta-data).
417 =item I<coerce =E<gt> (1|0)>
419 This will attempt to use coercion with the supplied type constraint to change
420 the value passed into any accessors or constructors. You B<must> have supplied
421 a type constraint in order for this to work. See L<Moose::Cookbook::Recipe5>
424 =item I<does =E<gt> $role_name>
426 This will accept the name of a role which the value stored in this attribute
427 is expected to have consumed.
429 =item I<required =E<gt> (1|0)>
431 This marks the attribute as being required. This means a I<defined> value must be
432 supplied during class construction, and the attribute may never be set to
433 C<undef> with an accessor.
435 =item I<weak_ref =E<gt> (1|0)>
437 This will tell the class to store the value of this attribute as a weakened
438 reference. If an attribute is a weakened reference, it B<cannot> also be
441 =item I<lazy =E<gt> (1|0)>
443 This will tell the class to not create this slot until absolutely necessary.
444 If an attribute is marked as lazy it B<must> have a default supplied.
446 =item I<auto_deref =E<gt> (1|0)>
448 This tells the accessor whether to automatically dereference the value returned.
449 This is only legal if your C<isa> option is either C<ArrayRef> or C<HashRef>.
451 =item I<metaclass =E<gt> $metaclass_name>
453 This tells the class to use a custom attribute metaclass for this particular
454 attribute. Custom attribute metaclasses are useful for extending the
455 capabilities of the I<has> keyword: they are the simplest way to extend the MOP,
456 but they are still a fairly advanced topic and too much to cover here. I will
457 try and write a recipe on them soon.
459 The default behavior here is to just load C<$metaclass_name>; however, we also
460 have a way to alias to a shorter name. This will first look to see if
461 B<Moose::Meta::Attribute::Custom::$metaclass_name> exists. If it does, Moose
462 will then check to see if that has the method C<register_implementation>, which
463 should return the actual name of the custom attribute metaclass. If there is no
464 C<register_implementation> method, it will fall back to using
465 B<Moose::Meta::Attribute::Custom::$metaclass_name> as the metaclass name.
467 =item I<trigger =E<gt> $code>
469 The I<trigger> option is a CODE reference which will be called after the value of
470 the attribute is set. The CODE ref will be passed the instance itself, the
471 updated value and the attribute meta-object (this is for more advanced fiddling
472 and can typically be ignored). You B<cannot> have a trigger on a read-only
475 =item I<handles =E<gt> ARRAY | HASH | REGEXP | ROLE | CODE>
477 The I<handles> option provides Moose classes with automated delegation features.
478 This is a pretty complex and powerful option. It accepts many different option
479 formats, each with its own benefits and drawbacks.
481 B<NOTE:> This feature is no longer experimental, but it may still have subtle
482 bugs lurking in the deeper corners. If you think you have found a bug, you
483 probably have, so please report it to me right away.
485 B<NOTE:> The class being delegated to does not need to be a Moose based class,
486 which is why this feature is especially useful when wrapping non-Moose classes.
488 All I<handles> option formats share the following traits:
490 You cannot override a locally defined method with a delegated method; an
491 exception will be thrown if you try. That is to say, if you define C<foo> in
492 your class, you cannot override it with a delegated C<foo>. This is almost never
493 something you would want to do, and if it is, you should do it by hand and not
496 You cannot override any of the methods found in Moose::Object, or the C<BUILD>
497 and C<DEMOLISH> methods. These will not throw an exception, but will silently
498 move on to the next method in the list. My reasoning for this is that you would
499 almost never want to do this, since it usually breaks your class. As with
500 overriding locally defined methods, if you do want to do this, you should do it
501 manually, not with Moose.
503 You do not I<need> to have a reader (or accessor) for the attribute in order
504 to delegate to it. Moose will create a means of accessing the value for you,
505 however this will be several times B<less> efficient then if you had given
506 the attribute a reader (or accessor) to use.
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 L<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 to retrieve it. Then it
754 sets your baseclass to Moose::Object or the value you pass in unless you already
755 have one. This is all done via C<init_meta> which takes the name of your class
756 and optionally a baseclass and a metaclass as arguments.
764 It should be noted that C<super> and C<inner> B<cannot> be used in the same
765 method. However, they may be combined within the same class hierarchy; see
766 F<t/014_override_augment_inner_super.t> for an example.
768 The reason for this is that C<super> is only valid within a method
769 with the C<override> modifier, and C<inner> will never be valid within an
770 C<override> method. In fact, C<augment> will skip over any C<override> methods
771 when searching for its appropriate C<inner>.
773 This might seem like a restriction, but I am of the opinion that keeping these
774 two features separate (yet interoperable) actually makes them easy to use, since
775 their behavior is then easier to predict. Time will tell whether I am right or
776 not (UPDATE: so far so good).
780 =head1 ACKNOWLEDGEMENTS
784 =item I blame Sam Vilain for introducing me to the insanity that is meta-models.
786 =item I blame Audrey Tang for then encouraging my meta-model habit in #perl6.
788 =item Without Yuval "nothingmuch" Kogman this module would not be possible,
789 and it certainly wouldn't have this name ;P
791 =item The basis of the TypeContraints module was Rob Kinyon's idea
792 originally, I just ran with it.
794 =item Thanks to mst & chansen and the whole #moose poose for all the
795 early ideas/feature-requests/encouragement/bug-finding.
797 =item Thanks to David "Theory" Wheeler for meta-discussions and spelling fixes.
805 =item L<http://www.iinteractive.com/moose>
807 This is the official web home of Moose, it contains links to our public SVN repo
808 as well as links to a number of talks and articles on Moose and Moose related
811 =item L<Class::MOP> documentation
813 =item The #moose channel on irc.perl.org
815 =item The Moose mailing list - moose@perl.org
817 =item Moose stats on ohloh.net - L<http://www.ohloh.net/projects/5788>
819 =item Several Moose extension modules in the L<MooseX::> namespace.
827 =item L<http://www.cs.utah.edu/plt/publications/oopsla04-gff.pdf>
829 This paper (suggested by lbr on #moose) was what lead to the implementation
830 of the C<super>/C<override> and C<inner>/C<augment> features. If you really
831 want to understand them, I suggest you read this.
837 All complex software has bugs lurking in it, and this module is no
838 exception. If you find a bug please either email me, or add the bug
843 Stevan Little E<lt>stevan@iinteractive.comE<gt>
845 B<with contributions from:>
851 Anders (Debolaz) Nor Berle
853 Nathan (kolibre) Gray
855 Christian (chansen) Hansen
857 Hans Dieter (confound) Pearcey
859 Eric (ewilhelm) Wilhelm
861 Guillermo (groditi) Roditi
863 Jess (castaway) Robinson
867 Robert (phaylon) Sedlacek
871 Scott (konobi) McWhirter
873 Shlomi (rindolf) Fish
875 Yuval (nothingmuch) Kogman
877 Chris (perigrin) Prather
879 Jonathan (jrockway) Rockway
881 Piotr (dexter) Roszatycki
887 ... and many other #moose folks
889 =head1 COPYRIGHT AND LICENSE
891 Copyright 2006-2008 by Infinity Interactive, Inc.
893 L<http://www.iinteractive.com>
895 This library is free software; you can redistribute it and/or modify
896 it under the same terms as Perl itself.