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(@_);
191 # this works because both pragmas set $^H (see perldoc perlvar)
192 # which affects the current compilation - i.e. the file who use'd
193 # us - which is why we don't need to do anything special to make
194 # it affect that file rather than this one (which is already compiled)
199 # we should never export to main
200 return if $CALLER eq 'main';
202 init_meta( $CALLER, 'Moose::Object' );
209 my $class = _get_caller(@_);
211 # loop through the exports ...
212 foreach my $name ( keys %exports ) {
215 if ( defined &{ $class . '::' . $name } ) {
216 my $keyword = \&{ $class . '::' . $name };
218 # make sure it is from Moose
219 my ($pkg_name) = Class::MOP::get_code_info($keyword);
221 next if $pkg_name ne 'Moose';
223 # and if it is from Moose then undef the slot
224 delete ${ $class . '::' }{$name};
231 ## make 'em all immutable
233 $_->meta->make_immutable(
234 inline_constructor => 0,
235 inline_accessors => 1, # these are Class::MOP accessors, so they need inlining
238 'Moose::Meta::Attribute',
239 'Moose::Meta::Class',
240 'Moose::Meta::Instance',
242 'Moose::Meta::TypeConstraint',
243 'Moose::Meta::TypeConstraint::Union',
244 'Moose::Meta::TypeConstraint::Parameterized',
245 'Moose::Meta::TypeCoercion',
247 'Moose::Meta::Method',
248 'Moose::Meta::Method::Accessor',
249 'Moose::Meta::Method::Constructor',
250 'Moose::Meta::Method::Destructor',
251 'Moose::Meta::Method::Overriden',
254 'Moose::Meta::Role::Method',
255 'Moose::Meta::Role::Method::Required',
266 Moose - A postmodern object system for Perl 5
271 use Moose; # automatically turns on strict and warnings
273 has 'x' => (is => 'rw', isa => 'Int');
274 has 'y' => (is => 'rw', isa => 'Int');
287 has 'z' => (is => 'rw', isa => 'Int');
289 after 'clear' => sub {
296 Moose is an extension of the Perl 5 object system.
298 =head2 Another object system!?!?
300 Yes, I know there has been an explosion recently of new ways to
301 build object's in Perl 5, most of them based on inside-out objects
302 and other such things. Moose is different because it is not a new
303 object system for Perl 5, but instead an extension of the existing
306 Moose is built on top of L<Class::MOP>, which is a metaclass system
307 for Perl 5. This means that Moose not only makes building normal
308 Perl 5 objects better, but it also provides the power of metaclass
311 =head2 Is this for real? Or is this just an experiment?
313 Moose is I<based> on the prototypes and experiments I did for the Perl 6
314 meta-model. However, Moose is B<NOT> an experiment/prototype; it is for B<real>.
316 =head2 Is this ready for use in production?
318 Yes, I believe that it is.
320 Moose has been used successfully in production environemnts by several people
321 and companies (including the one I work for). There are Moose applications
322 which have been in production with little or no issue now for well over a year.
323 I consider it highly stable and we are commited to keeping it stable.
325 Of course, in the end, you need to make this call yourself. If you have
326 any questions or concerns, please feel free to email me, or even the list
327 or just stop by #moose and ask away.
329 =head2 Is Moose just Perl 6 in Perl 5?
331 No. While Moose is very much inspired by Perl 6, it is not itself Perl 6.
332 Instead, it is an OO system for Perl 5. I built Moose because I was tired of
333 writing the same old boring Perl 5 OO code, and drooling over Perl 6 OO. So
334 instead of switching to Ruby, I wrote Moose :)
336 =head2 Wait, I<post> modern, I thought it was just I<modern>?
338 So I was reading Larry Wall's talk from the 1999 Linux World entitled
339 "Perl, the first postmodern computer language" in which he talks about how
340 he picked the features for Perl because he thought they were cool and he
341 threw out the ones that he thought sucked. This got me thinking about how
342 we have done the same thing in Moose. For Moose, we have "borrowed" features
343 from Perl 6, CLOS (LISP), Smalltalk, Java, BETA, OCaml, Ruby and more, and
344 the bits we didn't like (cause they sucked) we tossed aside. So for this
345 reason (and a few others) I have re-dubbed Moose a I<postmodern> object system.
349 =head2 Moose Extensions
351 The L<MooseX::> namespace is the official place to find Moose extensions.
352 There are a number of these modules out on CPAN right now the best way to
353 find them is to search for MooseX:: on search.cpan.org.
355 =head1 BUILDING CLASSES WITH MOOSE
357 Moose makes every attempt to provide as much convenience as possible during
358 class construction/definition, but still stay out of your way if you want it
359 to. Here are a few items to note when building classes with Moose.
361 Unless specified with C<extends>, any class which uses Moose will
362 inherit from L<Moose::Object>.
364 Moose will also manage all attributes (including inherited ones) that are
365 defined with C<has>. And (assuming you call C<new>, which is inherited from
366 L<Moose::Object>) this includes properly initializing all instance slots,
367 setting defaults where appropriate, and performing any type constraint checking
370 =head1 EXPORTED FUNCTIONS
372 Moose will export a number of functions into the class's namespace which
373 may then be used to set up the class. These functions all work directly
374 on the current class.
380 This is a method which provides access to the current class's metaclass.
382 =item B<extends (@superclasses)>
384 This function will set the superclass(es) for the current class.
386 This approach is recommended instead of C<use base>, because C<use base>
387 actually C<push>es onto the class's C<@ISA>, whereas C<extends> will
388 replace it. This is important to ensure that classes which do not have
389 superclasses still properly inherit from L<Moose::Object>.
391 =item B<with (@roles)>
393 This will apply a given set of C<@roles> to the local class. Role support
394 is currently under heavy development; see L<Moose::Role> for more details.
396 =item B<has $name =E<gt> %options>
398 This will install an attribute of a given C<$name> into the current class.
399 The C<%options> are the same as those provided by
400 L<Class::MOP::Attribute>, in addition to the list below which are provided
401 by Moose (L<Moose::Meta::Attribute> to be more specific):
405 =item I<is =E<gt> 'rw'|'ro'>
407 The I<is> option accepts either I<rw> (for read/write) or I<ro> (for read
408 only). These will create either a read/write accessor or a read-only
409 accessor respectively, using the same name as the C<$name> of the attribute.
411 If you need more control over how your accessors are named, you can use the
412 I<reader>, I<writer> and I<accessor> options inherited from
413 L<Class::MOP::Attribute>.
415 =item I<isa =E<gt> $type_name>
417 The I<isa> option uses Moose's type constraint facilities to set up runtime
418 type checking for this attribute. Moose will perform the checks during class
419 construction, and within any accessors. The C<$type_name> argument must be a
420 string. The string may be either a class name or a type defined using
421 Moose's type definition features. (Refer to L<Moose::Util::TypeConstraints>
422 for information on how to define a new type, and how to retrieve type meta-data).
424 =item I<coerce =E<gt> (1|0)>
426 This will attempt to use coercion with the supplied type constraint to change
427 the value passed into any accessors or constructors. You B<must> have supplied
428 a type constraint in order for this to work. See L<Moose::Cookbook::Recipe5>
431 =item I<does =E<gt> $role_name>
433 This will accept the name of a role which the value stored in this attribute
434 is expected to have consumed.
436 =item I<required =E<gt> (1|0)>
438 This marks the attribute as being required. This means a I<defined> value must be
439 supplied during class construction, and the attribute may never be set to
440 C<undef> with an accessor.
442 =item I<weak_ref =E<gt> (1|0)>
444 This will tell the class to store the value of this attribute as a weakened
445 reference. If an attribute is a weakened reference, it B<cannot> also be
448 =item I<lazy =E<gt> (1|0)>
450 This will tell the class to not create this slot until absolutely necessary.
451 If an attribute is marked as lazy it B<must> have a default supplied.
453 =item I<auto_deref =E<gt> (1|0)>
455 This tells the accessor whether to automatically dereference the value returned.
456 This is only legal if your C<isa> option is either C<ArrayRef> or C<HashRef>.
458 =item I<metaclass =E<gt> $metaclass_name>
460 This tells the class to use a custom attribute metaclass for this particular
461 attribute. Custom attribute metaclasses are useful for extending the
462 capabilities of the I<has> keyword: they are the simplest way to extend the MOP,
463 but they are still a fairly advanced topic and too much to cover here. I will
464 try and write a recipe on them soon.
466 The default behavior here is to just load C<$metaclass_name>; however, we also
467 have a way to alias to a shorter name. This will first look to see if
468 B<Moose::Meta::Attribute::Custom::$metaclass_name> exists. If it does, Moose
469 will then check to see if that has the method C<register_implementation>, which
470 should return the actual name of the custom attribute metaclass. If there is no
471 C<register_implementation> method, it will fall back to using
472 B<Moose::Meta::Attribute::Custom::$metaclass_name> as the metaclass name.
474 =item I<trigger =E<gt> $code>
476 The I<trigger> option is a CODE reference which will be called after the value of
477 the attribute is set. The CODE ref will be passed the instance itself, the
478 updated value and the attribute meta-object (this is for more advanced fiddling
479 and can typically be ignored). You B<cannot> have a trigger on a read-only
482 =item I<handles =E<gt> ARRAY | HASH | REGEXP | ROLE | CODE>
484 The I<handles> option provides Moose classes with automated delegation features.
485 This is a pretty complex and powerful option. It accepts many different option
486 formats, each with its own benefits and drawbacks.
488 B<NOTE:> This feature is no longer experimental, but it may still have subtle
489 bugs lurking in the deeper corners. If you think you have found a bug, you
490 probably have, so please report it to me right away.
492 B<NOTE:> The class being delegated to does not need to be a Moose based class,
493 which is why this feature is especially useful when wrapping non-Moose classes.
495 All I<handles> option formats share the following traits:
497 You cannot override a locally defined method with a delegated method; an
498 exception will be thrown if you try. That is to say, if you define C<foo> in
499 your class, you cannot override it with a delegated C<foo>. This is almost never
500 something you would want to do, and if it is, you should do it by hand and not
503 You cannot override any of the methods found in Moose::Object, or the C<BUILD>
504 and C<DEMOLISH> methods. These will not throw an exception, but will silently
505 move on to the next method in the list. My reasoning for this is that you would
506 almost never want to do this, since it usually breaks your class. As with
507 overriding locally defined methods, if you do want to do this, you should do it
508 manually, not with Moose.
510 You do not I<need> to have a reader (or accessor) for the attribute in order
511 to delegate to it. Moose will create a means of accessing the value for you,
512 however this will be several times B<less> efficient then if you had given
513 the attribute a reader (or accessor) to use.
515 Below is the documentation for each option format:
521 This is the most common usage for I<handles>. You basically pass a list of
522 method names to be delegated, and Moose will install a delegation method
527 This is the second most common usage for I<handles>. Instead of a list of
528 method names, you pass a HASH ref where each key is the method name you
529 want installed locally, and its value is the name of the original method
530 in the class being delegated to.
532 This can be very useful for recursive classes like trees. Here is a
533 quick example (soon to be expanded into a Moose::Cookbook::Recipe):
538 has 'node' => (is => 'rw', isa => 'Any');
543 default => sub { [] }
551 parent_node => 'node',
552 siblings => 'children',
556 In this example, the Tree package gets C<parent_node> and C<siblings> methods,
557 which delegate to the C<node> and C<children> methods (respectively) of the Tree
558 instance stored in the C<parent> slot.
562 The regexp option works very similar to the ARRAY option, except that it builds
563 the list of methods for you. It starts by collecting all possible methods of the
564 class being delegated to, then filters that list using the regexp supplied here.
566 B<NOTE:> An I<isa> option is required when using the regexp option format. This
567 is so that we can determine (at compile time) the method list from the class.
568 Without an I<isa> this is just not possible.
572 With the role option, you specify the name of a role whose "interface" then
573 becomes the list of methods to handle. The "interface" can be defined as; the
574 methods of the role and any required methods of the role. It should be noted
575 that this does B<not> include any method modifiers or generated attribute
576 methods (which is consistent with role composition).
580 This is the option to use when you really want to do something funky. You should
581 only use it if you really know what you are doing, as it involves manual
584 This takes a code reference, which should expect two arguments. The first is the
585 attribute meta-object this I<handles> is attached to. The second is the
586 metaclass of the class being delegated to. It expects you to return a hash (not
587 a HASH ref) of the methods you want mapped.
593 =item B<has +$name =E<gt> %options>
595 This is variation on the normal attibute creator C<has> which allows you to
596 clone and extend an attribute from a superclass. Here is a quick example:
604 default => 'Hello, I am a Foo'
612 has '+message' => (default => 'Hello I am My::Foo');
614 What is happening here is that B<My::Foo> is cloning the C<message> attribute
615 from its parent class B<Foo>, retaining the C<is =E<gt> 'rw'> and C<isa =E<gt>
616 'Str'> characteristics, but changing the value in C<default>.
618 This feature is restricted somewhat, so as to try and force at least I<some>
619 sanity into it. You are only allowed to change the following attributes:
625 Change the default value of an attribute.
629 Change whether the attribute attempts to coerce a value passed to it.
633 Change if the attribute is required to have a value.
635 =item I<documentation>
637 Change the documentation string associated with the attribute.
641 Change if the attribute lazily initializes the slot.
645 You I<are> allowed to change the type, B<if and only if> the new type is a
646 subtype of the old type.
650 You are allowed to B<add> a new C<handles> definition, but you are B<not>
651 allowed to I<change> one.
655 =item B<before $name|@names =E<gt> sub { ... }>
657 =item B<after $name|@names =E<gt> sub { ... }>
659 =item B<around $name|@names =E<gt> sub { ... }>
661 This three items are syntactic sugar for the before, after, and around method
662 modifier features that L<Class::MOP> provides. More information on these may be
663 found in the L<Class::MOP::Class documentation|Class::MOP::Class/"Method
668 The keyword C<super> is a no-op when called outside of an C<override> method. In
669 the context of an C<override> method, it will call the next most appropriate
670 superclass method with the same arguments as the original method.
672 =item B<override ($name, &sub)>
674 An C<override> method is a way of explicitly saying "I am overriding this
675 method from my superclass". You can call C<super> within this method, and
676 it will work as expected. The same thing I<can> be accomplished with a normal
677 method call and the C<SUPER::> pseudo-package; it is really your choice.
681 The keyword C<inner>, much like C<super>, is a no-op outside of the context of
682 an C<augment> method. You can think of C<inner> as being the inverse of
683 C<super>; the details of how C<inner> and C<augment> work is best described in
684 the L<Moose::Cookbook>.
686 =item B<augment ($name, &sub)>
688 An C<augment> method, is a way of explicitly saying "I am augmenting this
689 method from my superclass". Once again, the details of how C<inner> and
690 C<augment> work is best described in the L<Moose::Cookbook>.
694 This is the C<Carp::confess> function, and exported here because I use it
695 all the time. This feature may change in the future, so you have been warned.
699 This is the C<Scalar::Util::blessed> function, it is exported here because I
700 use it all the time. It is highly recommended that this is used instead of
701 C<ref> anywhere you need to test for an object's class name.
705 =head1 UNIMPORTING FUNCTIONS
709 Moose offers a way to remove the keywords it exports, through the C<unimport>
710 method. You simply have to say C<no Moose> at the bottom of your code for this
711 to work. Here is an example:
716 has 'first_name' => (is => 'rw', isa => 'Str');
717 has 'last_name' => (is => 'rw', isa => 'Str');
721 $self->first_name . ' ' . $self->last_name
724 no Moose; # keywords are removed from the Person package
726 =head1 EXTENDING AND EMBEDDING MOOSE
728 Moose also offers some options for extending or embedding it into your own
729 framework. The basic premise is to have something that sets up your class'
730 metaclass and export the moose declarators (C<has>, C<with>, C<extends>,...).
737 my $CALLER = caller();
742 # we should never export to main
743 return if $CALLER eq 'main';
744 Moose::init_meta( $CALLER, 'MyFramework::Base' );
745 Moose->import({into => $CALLER});
747 # Do my custom framework stuff
754 Moose's C<import> method supports the L<Sub::Exporter> form of C<{into =E<gt> $pkg}>
755 and C<{into_level =E<gt> 1}>
757 =head2 B<init_meta ($class, $baseclass, $metaclass)>
759 Moose does some boot strapping: it creates a metaclass object for your class,
760 and then injects a C<meta> accessor into your class to retrieve it. Then it
761 sets your baseclass to Moose::Object or the value you pass in unless you already
762 have one. This is all done via C<init_meta> which takes the name of your class
763 and optionally a baseclass and a metaclass as arguments.
771 It should be noted that C<super> and C<inner> B<cannot> be used in the same
772 method. However, they may be combined within the same class hierarchy; see
773 F<t/014_override_augment_inner_super.t> for an example.
775 The reason for this is that C<super> is only valid within a method
776 with the C<override> modifier, and C<inner> will never be valid within an
777 C<override> method. In fact, C<augment> will skip over any C<override> methods
778 when searching for its appropriate C<inner>.
780 This might seem like a restriction, but I am of the opinion that keeping these
781 two features separate (yet interoperable) actually makes them easy to use, since
782 their behavior is then easier to predict. Time will tell whether I am right or
783 not (UPDATE: so far so good).
787 =head1 ACKNOWLEDGEMENTS
791 =item I blame Sam Vilain for introducing me to the insanity that is meta-models.
793 =item I blame Audrey Tang for then encouraging my meta-model habit in #perl6.
795 =item Without Yuval "nothingmuch" Kogman this module would not be possible,
796 and it certainly wouldn't have this name ;P
798 =item The basis of the TypeContraints module was Rob Kinyon's idea
799 originally, I just ran with it.
801 =item Thanks to mst & chansen and the whole #moose poose for all the
802 early ideas/feature-requests/encouragement/bug-finding.
804 =item Thanks to David "Theory" Wheeler for meta-discussions and spelling fixes.
812 =item L<http://www.iinteractive.com/moose>
814 This is the official web home of Moose, it contains links to our public SVN repo
815 as well as links to a number of talks and articles on Moose and Moose related
818 =item L<Class::MOP> documentation
820 =item The #moose channel on irc.perl.org
822 =item The Moose mailing list - moose@perl.org
824 =item Moose stats on ohloh.net - L<http://www.ohloh.net/projects/5788>
826 =item Several Moose extension modules in the L<MooseX::> namespace.
834 =item L<http://www.cs.utah.edu/plt/publications/oopsla04-gff.pdf>
836 This paper (suggested by lbr on #moose) was what lead to the implementation
837 of the C<super>/C<override> and C<inner>/C<augment> features. If you really
838 want to understand them, I suggest you read this.
844 All complex software has bugs lurking in it, and this module is no
845 exception. If you find a bug please either email me, or add the bug
850 Stevan Little E<lt>stevan@iinteractive.comE<gt>
852 B<with contributions from:>
858 Anders (Debolaz) Nor Berle
860 Nathan (kolibre) Gray
862 Christian (chansen) Hansen
864 Hans Dieter (confound) Pearcey
866 Eric (ewilhelm) Wilhelm
868 Guillermo (groditi) Roditi
870 Jess (castaway) Robinson
874 Robert (phaylon) Sedlacek
878 Scott (konobi) McWhirter
880 Shlomi (rindolf) Fish
882 Yuval (nothingmuch) Kogman
884 Chris (perigrin) Prather
886 Jonathan (jrockway) Rockway
888 Piotr (dexter) Roszatycki
894 ... and many other #moose folks
896 =head1 COPYRIGHT AND LICENSE
898 Copyright 2006-2008 by Infinity Interactive, Inc.
900 L<http://www.iinteractive.com>
902 This library is free software; you can redistribute it and/or modify
903 it under the same terms as Perl itself.