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 =head2 Moose Extensions
363 The L<MooseX::> namespace is the official place to find Moose extensions.
364 There are a number of these modules out on CPAN right now the best way to
365 find them is to search for MooseX:: on search.cpan.org.
367 =head1 BUILDING CLASSES WITH MOOSE
369 Moose makes every attempt to provide as much convenience as possible during
370 class construction/definition, but still stay out of your way if you want it
371 to. Here are a few items to note when building classes with Moose.
373 Unless specified with C<extends>, any class which uses Moose will
374 inherit from L<Moose::Object>.
376 Moose will also manage all attributes (including inherited ones) that are
377 defined with C<has>. And (assuming you call C<new>, which is inherited from
378 L<Moose::Object>) this includes properly initializing all instance slots,
379 setting defaults where appropriate, and performing any type constraint checking
382 =head1 EXPORTED FUNCTIONS
384 Moose will export a number of functions into the class's namespace which
385 may then be used to set up the class. These functions all work directly
386 on the current class.
392 This is a method which provides access to the current class's metaclass.
394 =item B<extends (@superclasses)>
396 This function will set the superclass(es) for the current class.
398 This approach is recommended instead of C<use base>, because C<use base>
399 actually C<push>es onto the class's C<@ISA>, whereas C<extends> will
400 replace it. This is important to ensure that classes which do not have
401 superclasses still properly inherit from L<Moose::Object>.
403 =item B<with (@roles)>
405 This will apply a given set of C<@roles> to the local class. Role support
406 is currently under heavy development; see L<Moose::Role> for more details.
408 =item B<has $name =E<gt> %options>
410 This will install an attribute of a given C<$name> into the current class.
411 The C<%options> are the same as those provided by
412 L<Class::MOP::Attribute>, in addition to the list below which are provided
413 by Moose (L<Moose::Meta::Attribute> to be more specific):
417 =item I<is =E<gt> 'rw'|'ro'>
419 The I<is> option accepts either I<rw> (for read/write) or I<ro> (for read
420 only). These will create either a read/write accessor or a read-only
421 accessor respectively, using the same name as the C<$name> of the attribute.
423 If you need more control over how your accessors are named, you can use the
424 I<reader>, I<writer> and I<accessor> options inherited from
425 L<Class::MOP::Attribute>.
427 =item I<isa =E<gt> $type_name>
429 The I<isa> option uses Moose's type constraint facilities to set up runtime
430 type checking for this attribute. Moose will perform the checks during class
431 construction, and within any accessors. The C<$type_name> argument must be a
432 string. The string may be either a class name or a type defined using
433 Moose's type definition features. (Refer to L<Moose::Util::TypeConstraints>
434 for information on how to define a new type, and how to retrieve type meta-data).
436 =item I<coerce =E<gt> (1|0)>
438 This will attempt to use coercion with the supplied type constraint to change
439 the value passed into any accessors or constructors. You B<must> have supplied
440 a type constraint in order for this to work. See L<Moose::Cookbook::Recipe5>
443 =item I<does =E<gt> $role_name>
445 This will accept the name of a role which the value stored in this attribute
446 is expected to have consumed.
448 =item I<required =E<gt> (1|0)>
450 This marks the attribute as being required. This means a I<defined> value must be
451 supplied during class construction, and the attribute may never be set to
452 C<undef> with an accessor.
454 =item I<weak_ref =E<gt> (1|0)>
456 This will tell the class to store the value of this attribute as a weakened
457 reference. If an attribute is a weakened reference, it B<cannot> also be
460 =item I<lazy =E<gt> (1|0)>
462 This will tell the class to not create this slot until absolutely necessary.
463 If an attribute is marked as lazy it B<must> have a default supplied.
465 =item I<auto_deref =E<gt> (1|0)>
467 This tells the accessor whether to automatically dereference the value returned.
468 This is only legal if your C<isa> option is either C<ArrayRef> or C<HashRef>.
470 =item I<metaclass =E<gt> $metaclass_name>
472 This tells the class to use a custom attribute metaclass for this particular
473 attribute. Custom attribute metaclasses are useful for extending the
474 capabilities of the I<has> keyword: they are the simplest way to extend the MOP,
475 but they are still a fairly advanced topic and too much to cover here. I will
476 try and write a recipe on them soon.
478 The default behavior here is to just load C<$metaclass_name>; however, we also
479 have a way to alias to a shorter name. This will first look to see if
480 B<Moose::Meta::Attribute::Custom::$metaclass_name> exists. If it does, Moose
481 will then check to see if that has the method C<register_implemenetation>, which
482 should return the actual name of the custom attribute metaclass. If there is no
483 C<register_implemenetation> method, it will fall back to using
484 B<Moose::Meta::Attribute::Custom::$metaclass_name> as the metaclass name.
486 =item I<trigger =E<gt> $code>
488 The I<trigger> option is a CODE reference which will be called after the value of
489 the attribute is set. The CODE ref will be passed the instance itself, the
490 updated value and the attribute meta-object (this is for more advanced fiddling
491 and can typically be ignored). You B<cannot> have a trigger on a read-only
494 =item I<handles =E<gt> ARRAY | HASH | REGEXP | ROLE | CODE>
496 The I<handles> option provides Moose classes with automated delegation features.
497 This is a pretty complex and powerful option. It accepts many different option
498 formats, each with its own benefits and drawbacks.
500 B<NOTE:> This feature is no longer experimental, but it may still have subtle
501 bugs lurking in the deeper corners. If you think you have found a bug, you
502 probably have, so please report it to me right away.
504 B<NOTE:> The class being delegated to does not need to be a Moose based class,
505 which is why this feature is especially useful when wrapping non-Moose classes.
507 All I<handles> option formats share the following traits:
509 You cannot override a locally defined method with a delegated method; an
510 exception will be thrown if you try. That is to say, if you define C<foo> in
511 your class, you cannot override it with a delegated C<foo>. This is almost never
512 something you would want to do, and if it is, you should do it by hand and not
515 You cannot override any of the methods found in Moose::Object, or the C<BUILD>
516 and C<DEMOLISH> methods. These will not throw an exception, but will silently
517 move on to the next method in the list. My reasoning for this is that you would
518 almost never want to do this, since it usually breaks your class. As with
519 overriding locally defined methods, if you do want to do this, you should do it
520 manually, not with Moose.
522 Below is the documentation for each option format:
528 This is the most common usage for I<handles>. You basically pass a list of
529 method names to be delegated, and Moose will install a delegation method
534 This is the second most common usage for I<handles>. Instead of a list of
535 method names, you pass a HASH ref where each key is the method name you
536 want installed locally, and its value is the name of the original method
537 in the class being delegated to.
539 This can be very useful for recursive classes like trees. Here is a
540 quick example (soon to be expanded into a Moose::Cookbook::Recipe):
545 has 'node' => (is => 'rw', isa => 'Any');
550 default => sub { [] }
558 parent_node => 'node',
559 siblings => 'children',
563 In this example, the Tree package gets C<parent_node> and C<siblings> methods,
564 which delegate to the C<node> and C<children> methods (respectively) of the Tree
565 instance stored in the C<parent> slot.
569 The regexp option works very similar to the ARRAY option, except that it builds
570 the list of methods for you. It starts by collecting all possible methods of the
571 class being delegated to, then filters that list using the regexp supplied here.
573 B<NOTE:> An I<isa> option is required when using the regexp option format. This
574 is so that we can determine (at compile time) the method list from the class.
575 Without an I<isa> this is just not possible.
579 With the role option, you specify the name of a role whose "interface" then
580 becomes the list of methods to handle. The "interface" can be defined as; the
581 methods of the role and any required methods of the role. It should be noted
582 that this does B<not> include any method modifiers or generated attribute
583 methods (which is consistent with role composition).
587 This is the option to use when you really want to do something funky. You should
588 only use it if you really know what you are doing, as it involves manual
591 This takes a code reference, which should expect two arguments. The first is the
592 attribute meta-object this I<handles> is attached to. The second is the
593 metaclass of the class being delegated to. It expects you to return a hash (not
594 a HASH ref) of the methods you want mapped.
600 =item B<has +$name =E<gt> %options>
602 This is variation on the normal attibute creator C<has> which allows you to
603 clone and extend an attribute from a superclass. Here is a quick example:
611 default => 'Hello, I am a Foo'
619 has '+message' => (default => 'Hello I am My::Foo');
621 What is happening here is that B<My::Foo> is cloning the C<message> attribute
622 from its parent class B<Foo>, retaining the C<is =E<gt> 'rw'> and C<isa =E<gt>
623 'Str'> characteristics, but changing the value in C<default>.
625 This feature is restricted somewhat, so as to try and force at least I<some>
626 sanity into it. You are only allowed to change the following attributes:
632 Change the default value of an attribute.
636 Change whether the attribute attempts to coerce a value passed to it.
640 Change if the attribute is required to have a value.
642 =item I<documentation>
644 Change the documentation string associated with the attribute.
648 Change if the attribute lazily initializes the slot.
652 You I<are> allowed to change the type, B<if and only if> the new type is a
653 subtype of the old type.
657 You are allowed to B<add> a new C<handles> definition, but you are B<not>
658 allowed to I<change> one.
662 =item B<before $name|@names =E<gt> sub { ... }>
664 =item B<after $name|@names =E<gt> sub { ... }>
666 =item B<around $name|@names =E<gt> sub { ... }>
668 This three items are syntactic sugar for the before, after, and around method
669 modifier features that L<Class::MOP> provides. More information on these may be
670 found in the L<Class::MOP::Class documentation|Class::MOP::Class/"Method
675 The keyword C<super> is a no-op when called outside of an C<override> method. In
676 the context of an C<override> method, it will call the next most appropriate
677 superclass method with the same arguments as the original method.
679 =item B<override ($name, &sub)>
681 An C<override> method is a way of explicitly saying "I am overriding this
682 method from my superclass". You can call C<super> within this method, and
683 it will work as expected. The same thing I<can> be accomplished with a normal
684 method call and the C<SUPER::> pseudo-package; it is really your choice.
688 The keyword C<inner>, much like C<super>, is a no-op outside of the context of
689 an C<augment> method. You can think of C<inner> as being the inverse of
690 C<super>; the details of how C<inner> and C<augment> work is best described in
691 the L<Moose::Cookbook>.
693 =item B<augment ($name, &sub)>
695 An C<augment> method, is a way of explicitly saying "I am augmenting this
696 method from my superclass". Once again, the details of how C<inner> and
697 C<augment> work is best described in the L<Moose::Cookbook>.
701 This is the C<Carp::confess> function, and exported here because I use it
702 all the time. This feature may change in the future, so you have been warned.
706 This is the C<Scalar::Util::blessed> function, it is exported here because I
707 use it all the time. It is highly recommended that this is used instead of
708 C<ref> anywhere you need to test for an object's class name.
712 =head1 UNIMPORTING FUNCTIONS
716 Moose offers a way to remove the keywords it exports, through the C<unimport>
717 method. You simply have to say C<no Moose> at the bottom of your code for this
718 to work. Here is an example:
723 has 'first_name' => (is => 'rw', isa => 'Str');
724 has 'last_name' => (is => 'rw', isa => 'Str');
728 $self->first_name . ' ' . $self->last_name
731 no Moose; # keywords are removed from the Person package
733 =head1 EXTENDING AND EMBEDDING MOOSE
735 Moose also offers some options for extending or embedding it into your own
736 framework. The basic premise is to have something that sets up your class'
737 metaclass and export the moose declarators (C<has>, C<with>, C<extends>,...).
744 my $CALLER = caller();
749 # we should never export to main
750 return if $CALLER eq 'main';
751 Moose::init_meta( $CALLER, 'MyFramework::Base' );
752 Moose->import({into => $CALLER});
754 # Do my custom framework stuff
761 Moose's C<import> method supports the L<Sub::Exporter> form of C<{into =E<gt> $pkg}>
762 and C<{into_level =E<gt> 1}>
764 =head2 B<init_meta ($class, $baseclass, $metaclass)>
766 Moose does some boot strapping: it creates a metaclass object for your class,
767 and then injects a C<meta> accessor into your class to retrieve it. Then it
768 sets your baseclass to Moose::Object or the value you pass in unless you already
769 have one. This is all done via C<init_meta> which takes the name of your class
770 and optionally a baseclass and a metaclass as arguments.
778 It should be noted that C<super> and C<inner> B<cannot> be used in the same
779 method. However, they may be combined within the same class hierarchy; see
780 F<t/014_override_augment_inner_super.t> for an example.
782 The reason for this is that C<super> is only valid within a method
783 with the C<override> modifier, and C<inner> will never be valid within an
784 C<override> method. In fact, C<augment> will skip over any C<override> methods
785 when searching for its appropriate C<inner>.
787 This might seem like a restriction, but I am of the opinion that keeping these
788 two features separate (yet interoperable) actually makes them easy to use, since
789 their behavior is then easier to predict. Time will tell whether I am right or
790 not (UPDATE: so far so good).
794 =head1 ACKNOWLEDGEMENTS
798 =item I blame Sam Vilain for introducing me to the insanity that is meta-models.
800 =item I blame Audrey Tang for then encouraging my meta-model habit in #perl6.
802 =item Without Yuval "nothingmuch" Kogman this module would not be possible,
803 and it certainly wouldn't have this name ;P
805 =item The basis of the TypeContraints module was Rob Kinyon's idea
806 originally, I just ran with it.
808 =item Thanks to mst & chansen and the whole #moose poose for all the
809 early ideas/feature-requests/encouragement/bug-finding.
811 =item Thanks to David "Theory" Wheeler for meta-discussions and spelling fixes.
819 =item L<http://www.iinteractive.com/moose>
821 This is the official web home of Moose, it contains links to our public SVN repo
822 as well as links to a number of talks and articles on Moose and Moose related
825 =item L<Class::MOP> documentation
827 =item The #moose channel on irc.perl.org
829 =item The Moose mailing list - moose@perl.org
831 =item Moose stats on ohloh.net - L<http://www.ohloh.net/projects/5788>
833 =item Several Moose extension modules in the L<MooseX::> namespace.
841 =item L<http://www.cs.utah.edu/plt/publications/oopsla04-gff.pdf>
843 This paper (suggested by lbr on #moose) was what lead to the implementation
844 of the C<super>/C<override> and C<inner>/C<augment> features. If you really
845 want to understand them, I suggest you read this.
851 All complex software has bugs lurking in it, and this module is no
852 exception. If you find a bug please either email me, or add the bug
857 Stevan Little E<lt>stevan@iinteractive.comE<gt>
859 B<with contributions from:>
865 Anders (Debolaz) Nor Berle
867 Nathan (kolibre) Gray
869 Christian (chansen) Hansen
871 Hans Dieter (confound) Pearcey
873 Eric (ewilhelm) Wilhelm
875 Guillermo (groditi) Roditi
877 Jess (castaway) Robinson
881 Robert (phaylon) Sedlacek
885 Scott (konobi) McWhirter
887 Shlomi (rindolf) Fish
889 Yuval (nothingmuch) Kogman
891 Chris (perigrin) Prather
893 Jonathan (jrockway) Rockway
895 Piotr (dexter) Roszatycki
899 ... and many other #moose folks
901 =head1 COPYRIGHT AND LICENSE
903 Copyright 2006, 2007 by Infinity Interactive, Inc.
905 L<http://www.iinteractive.com>
907 This library is free software; you can redistribute it and/or modify
908 it under the same terms as Perl itself.