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 = 'Moose::Object' 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 $meta->superclasses();
83 return subname 'Moose::extends' => sub (@) {
84 confess "Must derive at least one class" unless @_;
85 Class::MOP::load_class($_) 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 $meta->superclasses(@_);
96 return subname 'Moose::with' => sub (@) {
97 Moose::Util::apply_all_roles($class->meta, @_)
102 return subname 'Moose::has' => sub ($;%) {
103 my ( $name, %options ) = @_;
104 my $attrs = ( ref($name) eq 'ARRAY' ) ? $name : [ ($name) ];
105 $class->meta->add_attribute( $_, %options ) for @$attrs;
110 return subname 'Moose::before' => sub (@&) {
112 my $meta = $class->meta;
113 $meta->add_before_method_modifier( $_, $code ) for @_;
118 return subname 'Moose::after' => sub (@&) {
120 my $meta = $class->meta;
121 $meta->add_after_method_modifier( $_, $code ) for @_;
126 return subname 'Moose::around' => sub (@&) {
128 my $meta = $class->meta;
129 $meta->add_around_method_modifier( $_, $code ) for @_;
136 $SUPER_SLOT{$CALLER} = \*{"${CALLER}::super"};
138 return subname 'Moose::super' => sub { };
142 return subname 'Moose::override' => sub ($&) {
143 my ( $name, $method ) = @_;
144 $class->meta->add_override_method_modifier( $name => $method );
151 $INNER_SLOT{$CALLER} = \*{"${CALLER}::inner"};
153 return subname 'Moose::inner' => sub { };
157 return subname 'Moose::augment' => sub (@&) {
158 my ( $name, $method ) = @_;
159 $class->meta->add_augment_method_modifier( $name => $method );
163 return \&Carp::confess;
166 return \&Scalar::Util::blessed;
170 my $exporter = Sub::Exporter::build_exporter(
172 exports => \%exports,
173 groups => { default => [':all'] }
177 # 1 extra level because it's called by import so there's a layer of indirection
181 ref $_[1] && defined $_[1]->{into}
183 : ref $_[1] && defined $_[1]->{into_level}
184 ? caller($offset + $_[1]->{into_level})
189 $CALLER = _get_caller(@_);
194 # we should never export to main
195 return if $CALLER eq 'main';
197 init_meta( $CALLER, 'Moose::Object' );
204 my $class = _get_caller(@_);
206 # loop through the exports ...
207 foreach my $name ( keys %exports ) {
210 if ( defined &{ $class . '::' . $name } ) {
211 my $keyword = \&{ $class . '::' . $name };
213 # make sure it is from Moose
214 my ($pkg_name) = Class::MOP::get_code_info($keyword);
216 next if $pkg_name ne 'Moose';
218 # and if it is from Moose then undef the slot
219 delete ${ $class . '::' }{$name};
226 ## make 'em all immutable
228 $_->meta->make_immutable(
229 inline_constructor => 0,
230 inline_accessors => 1, # these are Class::MOP accessors, so they need inlining
233 'Moose::Meta::Attribute',
234 'Moose::Meta::Class',
235 'Moose::Meta::Instance',
237 'Moose::Meta::TypeConstraint',
238 'Moose::Meta::TypeConstraint::Union',
239 'Moose::Meta::TypeConstraint::Parameterized',
240 'Moose::Meta::TypeCoercion',
242 'Moose::Meta::Method',
243 'Moose::Meta::Method::Accessor',
244 'Moose::Meta::Method::Constructor',
245 'Moose::Meta::Method::Destructor',
246 'Moose::Meta::Method::Overriden',
249 'Moose::Meta::Role::Method',
250 'Moose::Meta::Role::Method::Required',
261 Moose - A postmodern object system for Perl 5
266 use Moose; # automatically turns on strict and warnings
268 has 'x' => (is => 'rw', isa => 'Int');
269 has 'y' => (is => 'rw', isa => 'Int');
282 has 'z' => (is => 'rw', isa => 'Int');
284 after 'clear' => sub {
291 Moose is an extension of the Perl 5 object system.
293 =head2 Another object system!?!?
295 Yes, I know there has been an explosion recently of new ways to
296 build object's in Perl 5, most of them based on inside-out objects
297 and other such things. Moose is different because it is not a new
298 object system for Perl 5, but instead an extension of the existing
301 Moose is built on top of L<Class::MOP>, which is a metaclass system
302 for Perl 5. This means that Moose not only makes building normal
303 Perl 5 objects better, but it also provides the power of metaclass
306 =head2 Is this for real? Or is this just an experiment?
308 Moose is I<based> on the prototypes and experiments I did for the Perl 6
309 meta-model. However, Moose is B<NOT> an experiment/prototype; it is for B<real>.
311 =head2 Is this ready for use in production?
313 Yes, I believe that it is.
315 Moose has been used successfully in production environemnts by several people
316 and companies (including the one I work for). There are Moose applications
317 which have been in production with little or no issue now for well over a year.
318 I consider it highly stable and we are commited to keeping it stable.
320 Of course, in the end, you need to make this call yourself. If you have
321 any questions or concerns, please feel free to email me, or even the list
322 or just stop by #moose and ask away.
324 =head2 Is Moose just Perl 6 in Perl 5?
326 No. While Moose is very much inspired by Perl 6, it is not itself Perl 6.
327 Instead, it is an OO system for Perl 5. I built Moose because I was tired of
328 writing the same old boring Perl 5 OO code, and drooling over Perl 6 OO. So
329 instead of switching to Ruby, I wrote Moose :)
331 =head2 Wait, I<post> modern, I thought it was just I<modern>?
333 So I was reading Larry Wall's talk from the 1999 Linux World entitled
334 "Perl, the first postmodern computer language" in which he talks about how
335 he picked the features for Perl because he thought they were cool and he
336 threw out the ones that he thought sucked. This got me thinking about how
337 we have done the same thing in Moose. For Moose, we have "borrowed" features
338 from Perl 6, CLOS (LISP), Smalltalk, Java, BETA, OCaml, Ruby and more, and
339 the bits we didn't like (cause they sucked) we tossed aside. So for this
340 reason (and a few others) I have re-dubbed Moose a I<postmodern> object system.
344 =head2 Moose Extensions
346 The L<MooseX::> namespace is the official place to find Moose extensions.
347 There are a number of these modules out on CPAN right now the best way to
348 find them is to search for MooseX:: on search.cpan.org.
350 =head1 BUILDING CLASSES WITH MOOSE
352 Moose makes every attempt to provide as much convenience as possible during
353 class construction/definition, but still stay out of your way if you want it
354 to. Here are a few items to note when building classes with Moose.
356 Unless specified with C<extends>, any class which uses Moose will
357 inherit from L<Moose::Object>.
359 Moose will also manage all attributes (including inherited ones) that are
360 defined with C<has>. And (assuming you call C<new>, which is inherited from
361 L<Moose::Object>) this includes properly initializing all instance slots,
362 setting defaults where appropriate, and performing any type constraint checking
365 =head1 EXPORTED FUNCTIONS
367 Moose will export a number of functions into the class's namespace which
368 may then be used to set up the class. These functions all work directly
369 on the current class.
375 This is a method which provides access to the current class's metaclass.
377 =item B<extends (@superclasses)>
379 This function will set the superclass(es) for the current class.
381 This approach is recommended instead of C<use base>, because C<use base>
382 actually C<push>es onto the class's C<@ISA>, whereas C<extends> will
383 replace it. This is important to ensure that classes which do not have
384 superclasses still properly inherit from L<Moose::Object>.
386 =item B<with (@roles)>
388 This will apply a given set of C<@roles> to the local class. Role support
389 is currently under heavy development; see L<Moose::Role> for more details.
391 =item B<has $name =E<gt> %options>
393 This will install an attribute of a given C<$name> into the current class.
394 The C<%options> are the same as those provided by
395 L<Class::MOP::Attribute>, in addition to the list below which are provided
396 by Moose (L<Moose::Meta::Attribute> to be more specific):
400 =item I<is =E<gt> 'rw'|'ro'>
402 The I<is> option accepts either I<rw> (for read/write) or I<ro> (for read
403 only). These will create either a read/write accessor or a read-only
404 accessor respectively, using the same name as the C<$name> of the attribute.
406 If you need more control over how your accessors are named, you can use the
407 I<reader>, I<writer> and I<accessor> options inherited from
408 L<Class::MOP::Attribute>.
410 =item I<isa =E<gt> $type_name>
412 The I<isa> option uses Moose's type constraint facilities to set up runtime
413 type checking for this attribute. Moose will perform the checks during class
414 construction, and within any accessors. The C<$type_name> argument must be a
415 string. The string may be either a class name or a type defined using
416 Moose's type definition features. (Refer to L<Moose::Util::TypeConstraints>
417 for information on how to define a new type, and how to retrieve type meta-data).
419 =item I<coerce =E<gt> (1|0)>
421 This will attempt to use coercion with the supplied type constraint to change
422 the value passed into any accessors or constructors. You B<must> have supplied
423 a type constraint in order for this to work. See L<Moose::Cookbook::Recipe5>
426 =item I<does =E<gt> $role_name>
428 This will accept the name of a role which the value stored in this attribute
429 is expected to have consumed.
431 =item I<required =E<gt> (1|0)>
433 This marks the attribute as being required. This means a I<defined> value must be
434 supplied during class construction, and the attribute may never be set to
435 C<undef> with an accessor.
437 =item I<weak_ref =E<gt> (1|0)>
439 This will tell the class to store the value of this attribute as a weakened
440 reference. If an attribute is a weakened reference, it B<cannot> also be
443 =item I<lazy =E<gt> (1|0)>
445 This will tell the class to not create this slot until absolutely necessary.
446 If an attribute is marked as lazy it B<must> have a default supplied.
448 =item I<auto_deref =E<gt> (1|0)>
450 This tells the accessor whether to automatically dereference the value returned.
451 This is only legal if your C<isa> option is either C<ArrayRef> or C<HashRef>.
453 =item I<metaclass =E<gt> $metaclass_name>
455 This tells the class to use a custom attribute metaclass for this particular
456 attribute. Custom attribute metaclasses are useful for extending the
457 capabilities of the I<has> keyword: they are the simplest way to extend the MOP,
458 but they are still a fairly advanced topic and too much to cover here. I will
459 try and write a recipe on them soon.
461 The default behavior here is to just load C<$metaclass_name>; however, we also
462 have a way to alias to a shorter name. This will first look to see if
463 B<Moose::Meta::Attribute::Custom::$metaclass_name> exists. If it does, Moose
464 will then check to see if that has the method C<register_implementation>, which
465 should return the actual name of the custom attribute metaclass. If there is no
466 C<register_implementation> method, it will fall back to using
467 B<Moose::Meta::Attribute::Custom::$metaclass_name> as the metaclass name.
469 =item I<trigger =E<gt> $code>
471 The I<trigger> option is a CODE reference which will be called after the value of
472 the attribute is set. The CODE ref will be passed the instance itself, the
473 updated value and the attribute meta-object (this is for more advanced fiddling
474 and can typically be ignored). You B<cannot> have a trigger on a read-only
477 =item I<handles =E<gt> ARRAY | HASH | REGEXP | ROLE | CODE>
479 The I<handles> option provides Moose classes with automated delegation features.
480 This is a pretty complex and powerful option. It accepts many different option
481 formats, each with its own benefits and drawbacks.
483 B<NOTE:> This feature is no longer experimental, but it may still have subtle
484 bugs lurking in the deeper corners. If you think you have found a bug, you
485 probably have, so please report it to me right away.
487 B<NOTE:> The class being delegated to does not need to be a Moose based class,
488 which is why this feature is especially useful when wrapping non-Moose classes.
490 All I<handles> option formats share the following traits:
492 You cannot override a locally defined method with a delegated method; an
493 exception will be thrown if you try. That is to say, if you define C<foo> in
494 your class, you cannot override it with a delegated C<foo>. This is almost never
495 something you would want to do, and if it is, you should do it by hand and not
498 You cannot override any of the methods found in Moose::Object, or the C<BUILD>
499 and C<DEMOLISH> methods. These will not throw an exception, but will silently
500 move on to the next method in the list. My reasoning for this is that you would
501 almost never want to do this, since it usually breaks your class. As with
502 overriding locally defined methods, if you do want to do this, you should do it
503 manually, not with Moose.
505 You do not I<need> to have a reader (or accessor) for the attribute in order
506 to delegate to it. Moose will create a means of accessing the value for you,
507 however this will be several times B<less> efficient then if you had given
508 the attribute a reader (or accessor) to use.
510 Below is the documentation for each option format:
516 This is the most common usage for I<handles>. You basically pass a list of
517 method names to be delegated, and Moose will install a delegation method
522 This is the second most common usage for I<handles>. Instead of a list of
523 method names, you pass a HASH ref where each key is the method name you
524 want installed locally, and its value is the name of the original method
525 in the class being delegated to.
527 This can be very useful for recursive classes like trees. Here is a
528 quick example (soon to be expanded into a Moose::Cookbook::Recipe):
533 has 'node' => (is => 'rw', isa => 'Any');
538 default => sub { [] }
546 parent_node => 'node',
547 siblings => 'children',
551 In this example, the Tree package gets C<parent_node> and C<siblings> methods,
552 which delegate to the C<node> and C<children> methods (respectively) of the Tree
553 instance stored in the C<parent> slot.
557 The regexp option works very similar to the ARRAY option, except that it builds
558 the list of methods for you. It starts by collecting all possible methods of the
559 class being delegated to, then filters that list using the regexp supplied here.
561 B<NOTE:> An I<isa> option is required when using the regexp option format. This
562 is so that we can determine (at compile time) the method list from the class.
563 Without an I<isa> this is just not possible.
567 With the role option, you specify the name of a role whose "interface" then
568 becomes the list of methods to handle. The "interface" can be defined as; the
569 methods of the role and any required methods of the role. It should be noted
570 that this does B<not> include any method modifiers or generated attribute
571 methods (which is consistent with role composition).
575 This is the option to use when you really want to do something funky. You should
576 only use it if you really know what you are doing, as it involves manual
579 This takes a code reference, which should expect two arguments. The first is the
580 attribute meta-object this I<handles> is attached to. The second is the
581 metaclass of the class being delegated to. It expects you to return a hash (not
582 a HASH ref) of the methods you want mapped.
588 =item B<has +$name =E<gt> %options>
590 This is variation on the normal attibute creator C<has> which allows you to
591 clone and extend an attribute from a superclass. Here is a quick example:
599 default => 'Hello, I am a Foo'
607 has '+message' => (default => 'Hello I am My::Foo');
609 What is happening here is that B<My::Foo> is cloning the C<message> attribute
610 from its parent class B<Foo>, retaining the C<is =E<gt> 'rw'> and C<isa =E<gt>
611 'Str'> characteristics, but changing the value in C<default>.
613 This feature is restricted somewhat, so as to try and force at least I<some>
614 sanity into it. You are only allowed to change the following attributes:
620 Change the default value of an attribute.
624 Change whether the attribute attempts to coerce a value passed to it.
628 Change if the attribute is required to have a value.
630 =item I<documentation>
632 Change the documentation string associated with the attribute.
636 Change if the attribute lazily initializes the slot.
640 You I<are> allowed to change the type, B<if and only if> the new type is a
641 subtype of the old type.
645 You are allowed to B<add> a new C<handles> definition, but you are B<not>
646 allowed to I<change> one.
650 =item B<before $name|@names =E<gt> sub { ... }>
652 =item B<after $name|@names =E<gt> sub { ... }>
654 =item B<around $name|@names =E<gt> sub { ... }>
656 This three items are syntactic sugar for the before, after, and around method
657 modifier features that L<Class::MOP> provides. More information on these may be
658 found in the L<Class::MOP::Class documentation|Class::MOP::Class/"Method
663 The keyword C<super> is a no-op when called outside of an C<override> method. In
664 the context of an C<override> method, it will call the next most appropriate
665 superclass method with the same arguments as the original method.
667 =item B<override ($name, &sub)>
669 An C<override> method is a way of explicitly saying "I am overriding this
670 method from my superclass". You can call C<super> within this method, and
671 it will work as expected. The same thing I<can> be accomplished with a normal
672 method call and the C<SUPER::> pseudo-package; it is really your choice.
676 The keyword C<inner>, much like C<super>, is a no-op outside of the context of
677 an C<augment> method. You can think of C<inner> as being the inverse of
678 C<super>; the details of how C<inner> and C<augment> work is best described in
679 the L<Moose::Cookbook>.
681 =item B<augment ($name, &sub)>
683 An C<augment> method, is a way of explicitly saying "I am augmenting this
684 method from my superclass". Once again, the details of how C<inner> and
685 C<augment> work is best described in the L<Moose::Cookbook>.
689 This is the C<Carp::confess> function, and exported here because I use it
690 all the time. This feature may change in the future, so you have been warned.
694 This is the C<Scalar::Util::blessed> function, it is exported here because I
695 use it all the time. It is highly recommended that this is used instead of
696 C<ref> anywhere you need to test for an object's class name.
700 =head1 UNIMPORTING FUNCTIONS
704 Moose offers a way to remove the keywords it exports, through the C<unimport>
705 method. You simply have to say C<no Moose> at the bottom of your code for this
706 to work. Here is an example:
711 has 'first_name' => (is => 'rw', isa => 'Str');
712 has 'last_name' => (is => 'rw', isa => 'Str');
716 $self->first_name . ' ' . $self->last_name
719 no Moose; # keywords are removed from the Person package
721 =head1 EXTENDING AND EMBEDDING MOOSE
723 Moose also offers some options for extending or embedding it into your own
724 framework. The basic premise is to have something that sets up your class'
725 metaclass and export the moose declarators (C<has>, C<with>, C<extends>,...).
732 my $CALLER = caller();
737 # we should never export to main
738 return if $CALLER eq 'main';
739 Moose::init_meta( $CALLER, 'MyFramework::Base' );
740 Moose->import({into => $CALLER});
742 # Do my custom framework stuff
749 Moose's C<import> method supports the L<Sub::Exporter> form of C<{into =E<gt> $pkg}>
750 and C<{into_level =E<gt> 1}>
752 =head2 B<init_meta ($class, $baseclass, $metaclass)>
754 Moose does some boot strapping: it creates a metaclass object for your class,
755 and then injects a C<meta> accessor into your class to retrieve it. Then it
756 sets your baseclass to Moose::Object or the value you pass in unless you already
757 have one. This is all done via C<init_meta> which takes the name of your class
758 and optionally a baseclass and a metaclass as arguments.
766 It should be noted that C<super> and C<inner> B<cannot> be used in the same
767 method. However, they may be combined within the same class hierarchy; see
768 F<t/014_override_augment_inner_super.t> for an example.
770 The reason for this is that C<super> is only valid within a method
771 with the C<override> modifier, and C<inner> will never be valid within an
772 C<override> method. In fact, C<augment> will skip over any C<override> methods
773 when searching for its appropriate C<inner>.
775 This might seem like a restriction, but I am of the opinion that keeping these
776 two features separate (yet interoperable) actually makes them easy to use, since
777 their behavior is then easier to predict. Time will tell whether I am right or
778 not (UPDATE: so far so good).
782 =head1 ACKNOWLEDGEMENTS
786 =item I blame Sam Vilain for introducing me to the insanity that is meta-models.
788 =item I blame Audrey Tang for then encouraging my meta-model habit in #perl6.
790 =item Without Yuval "nothingmuch" Kogman this module would not be possible,
791 and it certainly wouldn't have this name ;P
793 =item The basis of the TypeContraints module was Rob Kinyon's idea
794 originally, I just ran with it.
796 =item Thanks to mst & chansen and the whole #moose poose for all the
797 early ideas/feature-requests/encouragement/bug-finding.
799 =item Thanks to David "Theory" Wheeler for meta-discussions and spelling fixes.
807 =item L<http://www.iinteractive.com/moose>
809 This is the official web home of Moose, it contains links to our public SVN repo
810 as well as links to a number of talks and articles on Moose and Moose related
813 =item L<Class::MOP> documentation
815 =item The #moose channel on irc.perl.org
817 =item The Moose mailing list - moose@perl.org
819 =item Moose stats on ohloh.net - L<http://www.ohloh.net/projects/5788>
821 =item Several Moose extension modules in the L<MooseX::> namespace.
829 =item L<http://www.cs.utah.edu/plt/publications/oopsla04-gff.pdf>
831 This paper (suggested by lbr on #moose) was what lead to the implementation
832 of the C<super>/C<override> and C<inner>/C<augment> features. If you really
833 want to understand them, I suggest you read this.
839 All complex software has bugs lurking in it, and this module is no
840 exception. If you find a bug please either email me, or add the bug
845 Stevan Little E<lt>stevan@iinteractive.comE<gt>
847 B<with contributions from:>
853 Anders (Debolaz) Nor Berle
855 Nathan (kolibre) Gray
857 Christian (chansen) Hansen
859 Hans Dieter (confound) Pearcey
861 Eric (ewilhelm) Wilhelm
863 Guillermo (groditi) Roditi
865 Jess (castaway) Robinson
869 Robert (phaylon) Sedlacek
873 Scott (konobi) McWhirter
875 Shlomi (rindolf) Fish
877 Yuval (nothingmuch) Kogman
879 Chris (perigrin) Prather
881 Jonathan (jrockway) Rockway
883 Piotr (dexter) Roszatycki
889 ... and many other #moose folks
891 =head1 COPYRIGHT AND LICENSE
893 Copyright 2006-2008 by Infinity Interactive, Inc.
895 L<http://www.iinteractive.com>
897 This library is free software; you can redistribute it and/or modify
898 it under the same terms as Perl itself.