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;
36 # make a subtype for each Moose class
39 => where { $_->isa($class) }
40 => optimize_as { blessed($_[0]) && $_[0]->isa($class) }
41 unless find_type_constraint($class);
44 if ($class->can('meta')) {
46 # this is the case where the metaclass pragma
47 # was used before the 'use Moose' statement to
48 # override a specific class
49 $meta = $class->meta();
50 (blessed($meta) && $meta->isa('Moose::Meta::Class'))
51 || confess "You already have a &meta function, but it does not return a Moose::Meta::Class";
55 # this is broken currently, we actually need
56 # to allow the possiblity of an inherited
57 # meta, which will not be visible until the
58 # user 'extends' first. This needs to have
59 # more intelligence to it
60 $meta = Moose::Meta::Class->initialize($class);
61 $meta->add_method('meta' => sub {
62 # re-initialize so it inherits properly
63 Moose::Meta::Class->initialize(blessed($_[0]) || $_[0]);
67 # make sure they inherit from Moose::Object
68 $meta->superclasses('Moose::Object')
69 unless $meta->superclasses();
75 return subname 'Moose::extends' => sub (@) {
76 confess "Must derive at least one class" unless @_;
77 Class::MOP::load_class($_) for @_;
78 # this checks the metaclass to make sure
79 # it is correct, sometimes it can get out
80 # of sync when the classes are being built
81 my $meta = $class->meta->_fix_metaclass_incompatability(@_);
82 $meta->superclasses(@_);
87 return subname 'Moose::with' => sub (@) {
89 confess "Must specify at least one role" unless @roles;
90 Class::MOP::load_class($_) for @roles;
91 $class->meta->_apply_all_roles(@roles);
96 return subname 'Moose::has' => sub ($;%) {
97 my ($name, %options) = @_;
98 my $attrs = (ref($name) eq 'ARRAY') ? $name : [($name)];
99 $class->meta->_process_attribute($_, %options) for @$attrs;
104 return subname 'Moose::before' => sub (@&) {
106 my $meta = $class->meta;
107 $meta->add_before_method_modifier($_, $code) for @_;
112 return subname 'Moose::after' => sub (@&) {
114 my $meta = $class->meta;
115 $meta->add_after_method_modifier($_, $code) for @_;
120 return subname 'Moose::around' => sub (@&) {
122 my $meta = $class->meta;
123 $meta->add_around_method_modifier($_, $code) for @_;
130 $SUPER_SLOT{$CALLER} = \*{"${CALLER}::super"};
132 return subname 'Moose::super' => sub {};
136 return subname 'Moose::override' => sub ($&) {
137 my ($name, $method) = @_;
138 $class->meta->add_override_method_modifier($name => $method);
145 $INNER_SLOT{$CALLER} = \*{"${CALLER}::inner"};
147 return subname 'Moose::inner' => sub {};
151 return subname 'Moose::augment' => sub (@&) {
152 my ($name, $method) = @_;
153 $class->meta->add_augment_method_modifier($name => $method);
158 # this is experimental, but I am not
159 # happy with it. If you want to try
160 # it, you will have to uncomment it
162 # There is a really good chance that
163 # this will be deprecated, dont get
166 # return subname 'Moose::self' => sub {};
169 # my $class = $CALLER;
170 # return subname 'Moose::method' => sub {
171 # my ($name, $method) = @_;
172 # $class->meta->add_method($name, sub {
175 # no warnings 'redefine';
176 # local *{$class->meta->name . '::self'} = sub { $self };
183 return \&Carp::confess;
186 return \&Scalar::Util::blessed;
190 my $exporter = Sub::Exporter::build_exporter({
191 exports => \%exports,
203 # we should never export to main
204 return if $CALLER eq 'main';
213 my $class = caller();
214 # loop through the exports ...
215 foreach my $name (keys %exports) {
218 if (defined &{$class . '::' . $name}) {
219 my $keyword = \&{$class . '::' . $name};
221 # make sure it is from Moose
222 my $pkg_name = eval { svref_2object($keyword)->GV->STASH->NAME };
224 next if $pkg_name ne 'Moose';
226 # and if it is from Moose then undef the slot
227 delete ${$class . '::'}{$name};
235 ## make 'em all immutable
237 $_->meta->make_immutable(
238 inline_constructor => 0,
239 inline_accessors => 1,
241 'Moose::Meta::Attribute',
242 'Moose::Meta::Class',
243 'Moose::Meta::Instance',
245 'Moose::Meta::TypeConstraint',
246 'Moose::Meta::TypeConstraint::Union',
247 'Moose::Meta::TypeConstraint::Container',
248 'Moose::Meta::TypeCoercion',
250 'Moose::Meta::Method',
251 'Moose::Meta::Method::Accessor',
252 'Moose::Meta::Method::Constructor',
253 'Moose::Meta::Method::Destructor',
254 'Moose::Meta::Method::Overriden',
257 'Moose::Meta::Role::Method',
258 'Moose::Meta::Role::Method::Required',
269 Moose - A complete modern object system for Perl 5
274 use Moose; # automatically turns on strict and warnings
276 has 'x' => (is => 'rw', isa => 'Int');
277 has 'y' => (is => 'rw', isa => 'Int');
290 has 'z' => (is => 'rw', isa => 'Int');
292 after 'clear' => sub {
299 Moose is an extension of the Perl 5 object system.
301 =head2 Another object system!?!?
303 Yes, I know there has been an explosion recently of new ways to
304 build object's in Perl 5, most of them based on inside-out objects
305 and other such things. Moose is different because it is not a new
306 object system for Perl 5, but instead an extension of the existing
309 Moose is built on top of L<Class::MOP>, which is a metaclass system
310 for Perl 5. This means that Moose not only makes building normal
311 Perl 5 objects better, but it also provides the power of metaclass
314 =head2 Is this for real? Or is this just an experiment?
316 Moose is I<based> on the prototypes and experiments I did for the Perl 6
317 meta-model. However, Moose is B<NOT> an experiment/prototype; it is for B<real>.
319 =head2 Is this ready for use in production?
321 Yes, I believe that it is.
323 I have two medium-to-large-ish web applications which use Moose heavily
324 and have been in production (without issue) for several months now. At
325 $work, we are re-writing our core offering in it. And several people on
326 #moose have been using it (in production) for several months now as well.
328 Of course, in the end, you need to make this call yourself. If you have
329 any questions or concerns, please feel free to email me, or even the list
330 or just stop by #moose and ask away.
332 =head2 Is Moose just Perl 6 in Perl 5?
334 No. While Moose is very much inspired by Perl 6, it is not itself Perl 6.
335 Instead, it is an OO system for Perl 5. I built Moose because I was tired of
336 writing the same old boring Perl 5 OO code, and drooling over Perl 6 OO. So
337 instead of switching to Ruby, I wrote Moose :)
339 =head1 BUILDING CLASSES WITH MOOSE
341 Moose makes every attempt to provide as much convenience as possible during
342 class construction/definition, but still stay out of your way if you want it
343 to. Here are a few items to note when building classes with Moose.
345 Unless specified with C<extends>, any class which uses Moose will
346 inherit from L<Moose::Object>.
348 Moose will also manage all attributes (including inherited ones) that are
349 defined with C<has>. And (assuming you call C<new>, which is inherited from
350 L<Moose::Object>) this includes properly initializing all instance slots,
351 setting defaults where appropriate, and performing any type constraint checking
354 =head1 EXPORTED FUNCTIONS
356 Moose will export a number of functions into the class's namespace which
357 may then be used to set up the class. These functions all work directly
358 on the current class.
364 This is a method which provides access to the current class's metaclass.
366 =item B<extends (@superclasses)>
368 This function will set the superclass(es) for the current class.
370 This approach is recommended instead of C<use base>, because C<use base>
371 actually C<push>es onto the class's C<@ISA>, whereas C<extends> will
372 replace it. This is important to ensure that classes which do not have
373 superclasses still properly inherit from L<Moose::Object>.
375 =item B<with (@roles)>
377 This will apply a given set of C<@roles> to the local class. Role support
378 is currently under heavy development; see L<Moose::Role> for more details.
380 =item B<has $name =E<gt> %options>
382 This will install an attribute of a given C<$name> into the current class.
383 The C<%options> are the same as those provided by
384 L<Class::MOP::Attribute>, in addition to the list below which are provided
385 by Moose (L<Moose::Meta::Attribute> to be more specific):
389 =item I<is =E<gt> 'rw'|'ro'>
391 The I<is> option accepts either I<rw> (for read/write) or I<ro> (for read
392 only). These will create either a read/write accessor or a read-only
393 accessor respectively, using the same name as the C<$name> of the attribute.
395 If you need more control over how your accessors are named, you can use the
396 I<reader>, I<writer> and I<accessor> options inherited from
397 L<Class::MOP::Attribute>.
399 =item I<isa =E<gt> $type_name>
401 The I<isa> option uses Moose's type constraint facilities to set up runtime
402 type checking for this attribute. Moose will perform the checks during class
403 construction, and within any accessors. The C<$type_name> argument must be a
404 string. The string may be either a class name or a type defined using
405 Moose's type definition features. (Refer to L<Moose::Util::TypeConstraints>
406 for information on how to define a new type).
408 =item I<coerce =E<gt> (1|0)>
410 This will attempt to use coercion with the supplied type constraint to change
411 the value passed into any accessors or constructors. You B<must> have supplied
412 a type constraint in order for this to work. See L<Moose::Cookbook::Recipe5>
415 =item I<does =E<gt> $role_name>
417 This will accept the name of a role which the value stored in this attribute
418 is expected to have consumed.
420 =item I<required =E<gt> (1|0)>
422 This marks the attribute as being required. This means a I<defined> value must be
423 supplied during class construction, and the attribute may never be set to
424 C<undef> with an accessor.
426 =item I<weak_ref =E<gt> (1|0)>
428 This will tell the class to store the value of this attribute as a weakened
429 reference. If an attribute is a weakened reference, it B<cannot> also be
432 =item I<lazy =E<gt> (1|0)>
434 This will tell the class to not create this slot until absolutely necessary.
435 If an attribute is marked as lazy it B<must> have a default supplied.
437 =item I<auto_deref =E<gt> (1|0)>
439 This tells the accessor whether to automatically dereference the value returned.
440 This is only legal if your C<isa> option is either C<ArrayRef> or C<HashRef>.
442 =item I<metaclass =E<gt> $metaclass_name>
444 This tells the class to use a custom attribute metaclass for this particular
445 attribute. Custom attribute metaclasses are useful for extending the
446 capabilities of the I<has> keyword: they are the simplest way to extend the MOP,
447 but they are still a fairly advanced topic and too much to cover here. I will
448 try and write a recipe on them soon.
450 The default behavior here is to just load C<$metaclass_name>; however, we also
451 have a way to alias to a shorter name. This will first look to see if
452 B<Moose::Meta::Attribute::Custom::$metaclass_name> exists. If it does, Moose
453 will then check to see if that has the method C<register_implemenetation>, which
454 should return the actual name of the custom attribute metaclass. If there is no
455 C<register_implemenetation> method, it will fall back to using
456 B<Moose::Meta::Attribute::Custom::$metaclass_name> as the metaclass name.
458 =item I<trigger =E<gt> $code>
460 The I<trigger> option is a CODE reference which will be called after the value of
461 the attribute is set. The CODE ref will be passed the instance itself, the
462 updated value and the attribute meta-object (this is for more advanced fiddling
463 and can typically be ignored). You B<cannot> have a trigger on a read-only
466 =item I<handles =E<gt> ARRAY | HASH | REGEXP | ROLE | CODE>
468 The I<handles> option provides Moose classes with automated delegation features.
469 This is a pretty complex and powerful option. It accepts many different option
470 formats, each with its own benefits and drawbacks.
472 B<NOTE:> This feature is no longer experimental, but it may still have subtle
473 bugs lurking in the deeper corners. If you think you have found a bug, you
474 probably have, so please report it to me right away.
476 B<NOTE:> The class being delegated to does not need to be a Moose based class,
477 which is why this feature is especially useful when wrapping non-Moose classes.
479 All I<handles> option formats share the following traits:
481 You cannot override a locally defined method with a delegated method; an
482 exception will be thrown if you try. That is to say, if you define C<foo> in
483 your class, you cannot override it with a delegated C<foo>. This is almost never
484 something you would want to do, and if it is, you should do it by hand and not
487 You cannot override any of the methods found in Moose::Object, or the C<BUILD>
488 and C<DEMOLISH> methods. These will not throw an exception, but will silently
489 move on to the next method in the list. My reasoning for this is that you would
490 almost never want to do this, since it usually breaks your class. As with
491 overriding locally defined methods, if you do want to do this, you should do it
492 manually, not with Moose.
494 Below is the documentation for each option format:
500 This is the most common usage for I<handles>. You basically pass a list of
501 method names to be delegated, and Moose will install a delegation method
506 This is the second most common usage for I<handles>. Instead of a list of
507 method names, you pass a HASH ref where each key is the method name you
508 want installed locally, and its value is the name of the original method
509 in the class being delegated to.
511 This can be very useful for recursive classes like trees. Here is a
512 quick example (soon to be expanded into a Moose::Cookbook::Recipe):
517 has 'node' => (is => 'rw', isa => 'Any');
522 default => sub { [] }
530 parent_node => 'node',
531 siblings => 'children',
535 In this example, the Tree package gets C<parent_node> and C<siblings> methods,
536 which delegate to the C<node> and C<children> methods (respectively) of the Tree
537 instance stored in the C<parent> slot.
541 The regexp option works very similar to the ARRAY option, except that it builds
542 the list of methods for you. It starts by collecting all possible methods of the
543 class being delegated to, then filters that list using the regexp supplied here.
545 B<NOTE:> An I<isa> option is required when using the regexp option format. This
546 is so that we can determine (at compile time) the method list from the class.
547 Without an I<isa> this is just not possible.
551 With the role option, you specify the name of a role whose "interface" then
552 becomes the list of methods to handle. The "interface" can be defined as; the
553 methods of the role and any required methods of the role. It should be noted
554 that this does B<not> include any method modifiers or generated attribute
555 methods (which is consistent with role composition).
559 This is the option to use when you really want to do something funky. You should
560 only use it if you really know what you are doing, as it involves manual
563 This takes a code reference, which should expect two arguments. The first is the
564 attribute meta-object this I<handles> is attached to. The second is the
565 metaclass of the class being delegated to. It expects you to return a hash (not
566 a HASH ref) of the methods you want mapped.
572 =item B<has +$name =E<gt> %options>
574 This is variation on the normal attibute creator C<has> which allows you to
575 clone and extend an attribute from a superclass. Here is a quick example:
583 default => 'Hello, I am a Foo'
591 has '+message' => (default => 'Hello I am My::Foo');
593 What is happening here is that B<My::Foo> is cloning the C<message> attribute
594 from its parent class B<Foo>, retaining the C<is =E<gt> 'rw'> and C<isa =E<gt>
595 'Str'> characteristics, but changing the value in C<default>.
597 This feature is restricted somewhat, so as to try and force at least I<some>
598 sanity into it. You are only allowed to change the following attributes:
604 Change the default value of an attribute.
608 Change whether the attribute attempts to coerce a value passed to it.
612 Change if the attribute is required to have a value.
614 =item I<documentation>
616 Change the documentation string associated with the attribute.
620 Change if the attribute lazily initializes the slot.
624 You I<are> allowed to change the type, B<if and only if> the new type is a
625 subtype of the old type.
629 You are allowed to B<add> a new C<handles> definition, but you are B<not>
630 allowed to I<change> one.
634 =item B<before $name|@names =E<gt> sub { ... }>
636 =item B<after $name|@names =E<gt> sub { ... }>
638 =item B<around $name|@names =E<gt> sub { ... }>
640 This three items are syntactic sugar for the before, after, and around method
641 modifier features that L<Class::MOP> provides. More information on these may be
642 found in the L<Class::MOP::Class documentation|Class::MOP::Class/"Method
647 The keyword C<super> is a no-op when called outside of an C<override> method. In
648 the context of an C<override> method, it will call the next most appropriate
649 superclass method with the same arguments as the original method.
651 =item B<override ($name, &sub)>
653 An C<override> method is a way of explicitly saying "I am overriding this
654 method from my superclass". You can call C<super> within this method, and
655 it will work as expected. The same thing I<can> be accomplished with a normal
656 method call and the C<SUPER::> pseudo-package; it is really your choice.
660 The keyword C<inner>, much like C<super>, is a no-op outside of the context of
661 an C<augment> method. You can think of C<inner> as being the inverse of
662 C<super>; the details of how C<inner> and C<augment> work is best described in
663 the L<Moose::Cookbook>.
665 =item B<augment ($name, &sub)>
667 An C<augment> method, is a way of explicitly saying "I am augmenting this
668 method from my superclass". Once again, the details of how C<inner> and
669 C<augment> work is best described in the L<Moose::Cookbook>.
673 This is the C<Carp::confess> function, and exported here because I use it
674 all the time. This feature may change in the future, so you have been warned.
678 This is the C<Scalar::Util::blessed> function, it is exported here because I
679 use it all the time. It is highly recommended that this is used instead of
680 C<ref> anywhere you need to test for an object's class name.
684 =head1 UNIMPORTING FUNCTIONS
688 Moose offers a way to remove the keywords it exports, through the C<unimport>
689 method. You simply have to say C<no Moose> at the bottom of your code for this
690 to work. Here is an example:
695 has 'first_name' => (is => 'rw', isa => 'Str');
696 has 'last_name' => (is => 'rw', isa => 'Str');
700 $self->first_name . ' ' . $self->last_name
703 no Moose; # keywords are removed from the Person package
711 It should be noted that C<super> and C<inner> B<cannot> be used in the same
712 method. However, they may be combined within the same class hierarchy; see
713 F<t/014_override_augment_inner_super.t> for an example.
715 The reason for this is that C<super> is only valid within a method
716 with the C<override> modifier, and C<inner> will never be valid within an
717 C<override> method. In fact, C<augment> will skip over any C<override> methods
718 when searching for its appropriate C<inner>.
720 This might seem like a restriction, but I am of the opinion that keeping these
721 two features separate (yet interoperable) actually makes them easy to use, since
722 their behavior is then easier to predict. Time will tell whether I am right or
723 not (UPDATE: so far so good).
727 =head1 ACKNOWLEDGEMENTS
731 =item I blame Sam Vilain for introducing me to the insanity that is meta-models.
733 =item I blame Audrey Tang for then encouraging my meta-model habit in #perl6.
735 =item Without Yuval "nothingmuch" Kogman this module would not be possible,
736 and it certainly wouldn't have this name ;P
738 =item The basis of the TypeContraints module was Rob Kinyon's idea
739 originally, I just ran with it.
741 =item Thanks to mst & chansen and the whole #moose poose for all the
742 early ideas/feature-requests/encouragement/bug-finding.
744 =item Thanks to David "Theory" Wheeler for meta-discussions and spelling fixes.
752 =item L<http://www.iinteractive.com/moose>
754 This is the official web home of Moose, it contains links to our public SVN repo
755 as well as links to a number of talks and articles on Moose and Moose related
758 =item L<Class::MOP> documentation
760 =item The #moose channel on irc.perl.org
762 =item The Moose mailing list - moose@perl.org
764 =item Moose stats on ohloh.net - L<http://www.ohloh.net/projects/5788>
772 =item L<http://www.cs.utah.edu/plt/publications/oopsla04-gff.pdf>
774 This paper (suggested by lbr on #moose) was what lead to the implementation
775 of the C<super>/C<override> and C<inner>/C<augment> features. If you really
776 want to understand them, I suggest you read this.
782 All complex software has bugs lurking in it, and this module is no
783 exception. If you find a bug please either email me, or add the bug
788 Stevan Little E<lt>stevan@iinteractive.comE<gt>
790 B<with contributions from:>
796 Anders (Debolaz) Nor Berle
798 Nathan (kolibre) Gray
800 Christian (chansen) Hansen
802 Eric (ewilhelm) Wilhelm
804 Guillermo (groditi) Roditi
806 Jess (castaway) Robinson
810 Robert (phaylon) Sedlacek
814 Scott (konobi) McWhirter
816 Shlomi (rindolf) Fish
818 Yuval (nothingmuch) Kogman
820 Chris (perigrin) Prather
822 ... and many other #moose folks
824 =head1 COPYRIGHT AND LICENSE
826 Copyright 2006, 2007 by Infinity Interactive, Inc.
828 L<http://www.iinteractive.com>
830 This library is free software; you can redistribute it and/or modify
831 it under the same terms as Perl itself.