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 ($;%) {
104 die 'Usage: has \'name\' => ( key => value, ... )' if @_ == 1;
106 my $attrs = ( ref($name) eq 'ARRAY' ) ? $name : [ ($name) ];
107 $class->meta->add_attribute( $_, %options ) for @$attrs;
112 return subname 'Moose::before' => sub (@&) {
114 my $meta = $class->meta;
115 $meta->add_before_method_modifier( $_, $code ) for @_;
120 return subname 'Moose::after' => sub (@&) {
122 my $meta = $class->meta;
123 $meta->add_after_method_modifier( $_, $code ) for @_;
128 return subname 'Moose::around' => sub (@&) {
130 my $meta = $class->meta;
131 $meta->add_around_method_modifier( $_, $code ) for @_;
138 $SUPER_SLOT{$CALLER} = \*{"${CALLER}::super"};
140 return subname 'Moose::super' => sub { };
144 return subname 'Moose::override' => sub ($&) {
145 my ( $name, $method ) = @_;
146 $class->meta->add_override_method_modifier( $name => $method );
153 $INNER_SLOT{$CALLER} = \*{"${CALLER}::inner"};
155 return subname 'Moose::inner' => sub { };
159 return subname 'Moose::augment' => sub (@&) {
160 my ( $name, $method ) = @_;
161 $class->meta->add_augment_method_modifier( $name => $method );
165 return \&Carp::confess;
168 return \&Scalar::Util::blessed;
172 my $exporter = Sub::Exporter::build_exporter(
174 exports => \%exports,
175 groups => { default => [':all'] }
179 # 1 extra level because it's called by import so there's a layer of indirection
183 ref $_[1] && defined $_[1]->{into}
185 : ref $_[1] && defined $_[1]->{into_level}
186 ? caller($offset + $_[1]->{into_level})
191 $CALLER = _get_caller(@_);
193 # this works because both pragmas set $^H (see perldoc perlvar)
194 # which affects the current compilation - i.e. the file who use'd
195 # us - which is why we don't need to do anything special to make
196 # it affect that file rather than this one (which is already compiled)
201 # we should never export to main
202 return if $CALLER eq 'main';
204 init_meta( $CALLER, 'Moose::Object' );
211 my $class = _get_caller(@_);
213 # loop through the exports ...
214 foreach my $name ( keys %exports ) {
217 if ( defined &{ $class . '::' . $name } ) {
218 my $keyword = \&{ $class . '::' . $name };
220 # make sure it is from Moose
221 my ($pkg_name) = Class::MOP::get_code_info($keyword);
223 next if $pkg_name ne 'Moose';
225 # and if it is from Moose then undef the slot
226 delete ${ $class . '::' }{$name};
233 ## make 'em all immutable
235 $_->meta->make_immutable(
236 inline_constructor => 0,
237 inline_accessors => 1, # these are Class::MOP accessors, so they need inlining
240 'Moose::Meta::Attribute',
241 'Moose::Meta::Class',
242 'Moose::Meta::Instance',
244 'Moose::Meta::TypeConstraint',
245 'Moose::Meta::TypeConstraint::Union',
246 'Moose::Meta::TypeConstraint::Parameterized',
247 'Moose::Meta::TypeCoercion',
249 'Moose::Meta::Method',
250 'Moose::Meta::Method::Accessor',
251 'Moose::Meta::Method::Constructor',
252 'Moose::Meta::Method::Destructor',
253 'Moose::Meta::Method::Overriden',
256 'Moose::Meta::Role::Method',
257 'Moose::Meta::Role::Method::Required',
268 Moose - A postmodern object system for Perl 5
273 use Moose; # automatically turns on strict and warnings
275 has 'x' => (is => 'rw', isa => 'Int');
276 has 'y' => (is => 'rw', isa => 'Int');
289 has 'z' => (is => 'rw', isa => 'Int');
291 after 'clear' => sub {
298 Moose is an extension of the Perl 5 object system.
300 =head2 Another object system!?!?
302 Yes, I know there has been an explosion recently of new ways to
303 build object's in Perl 5, most of them based on inside-out objects
304 and other such things. Moose is different because it is not a new
305 object system for Perl 5, but instead an extension of the existing
308 Moose is built on top of L<Class::MOP>, which is a metaclass system
309 for Perl 5. This means that Moose not only makes building normal
310 Perl 5 objects better, but it also provides the power of metaclass
313 =head2 Is this for real? Or is this just an experiment?
315 Moose is I<based> on the prototypes and experiments I did for the Perl 6
316 meta-model. However, Moose is B<NOT> an experiment/prototype; it is for B<real>.
318 =head2 Is this ready for use in production?
320 Yes, I believe that it is.
322 Moose has been used successfully in production environemnts by several people
323 and companies (including the one I work for). There are Moose applications
324 which have been in production with little or no issue now for well over a year.
325 I consider it highly stable and we are commited to keeping it stable.
327 Of course, in the end, you need to make this call yourself. If you have
328 any questions or concerns, please feel free to email me, or even the list
329 or just stop by #moose and ask away.
331 =head2 Is Moose just Perl 6 in Perl 5?
333 No. While Moose is very much inspired by Perl 6, it is not itself Perl 6.
334 Instead, it is an OO system for Perl 5. I built Moose because I was tired of
335 writing the same old boring Perl 5 OO code, and drooling over Perl 6 OO. So
336 instead of switching to Ruby, I wrote Moose :)
338 =head2 Wait, I<post> modern, I thought it was just I<modern>?
340 So I was reading Larry Wall's talk from the 1999 Linux World entitled
341 "Perl, the first postmodern computer language" in which he talks about how
342 he picked the features for Perl because he thought they were cool and he
343 threw out the ones that he thought sucked. This got me thinking about how
344 we have done the same thing in Moose. For Moose, we have "borrowed" features
345 from Perl 6, CLOS (LISP), Smalltalk, Java, BETA, OCaml, Ruby and more, and
346 the bits we didn't like (cause they sucked) we tossed aside. So for this
347 reason (and a few others) I have re-dubbed Moose a I<postmodern> object system.
351 =head2 Moose Extensions
353 The L<MooseX::> namespace is the official place to find Moose extensions.
354 There are a number of these modules out on CPAN right now the best way to
355 find them is to search for MooseX:: on search.cpan.org.
357 =head1 BUILDING CLASSES WITH MOOSE
359 Moose makes every attempt to provide as much convenience as possible during
360 class construction/definition, but still stay out of your way if you want it
361 to. Here are a few items to note when building classes with Moose.
363 Unless specified with C<extends>, any class which uses Moose will
364 inherit from L<Moose::Object>.
366 Moose will also manage all attributes (including inherited ones) that are
367 defined with C<has>. And (assuming you call C<new>, which is inherited from
368 L<Moose::Object>) this includes properly initializing all instance slots,
369 setting defaults where appropriate, and performing any type constraint checking
372 =head1 EXPORTED FUNCTIONS
374 Moose will export a number of functions into the class's namespace which
375 may then be used to set up the class. These functions all work directly
376 on the current class.
382 This is a method which provides access to the current class's metaclass.
384 =item B<extends (@superclasses)>
386 This function will set the superclass(es) for the current class.
388 This approach is recommended instead of C<use base>, because C<use base>
389 actually C<push>es onto the class's C<@ISA>, whereas C<extends> will
390 replace it. This is important to ensure that classes which do not have
391 superclasses still properly inherit from L<Moose::Object>.
393 =item B<with (@roles)>
395 This will apply a given set of C<@roles> to the local class. Role support
396 is currently under heavy development; see L<Moose::Role> for more details.
398 =item B<has $name =E<gt> %options>
400 This will install an attribute of a given C<$name> into the current class.
401 The C<%options> are the same as those provided by
402 L<Class::MOP::Attribute>, in addition to the list below which are provided
403 by Moose (L<Moose::Meta::Attribute> to be more specific):
407 =item I<is =E<gt> 'rw'|'ro'>
409 The I<is> option accepts either I<rw> (for read/write) or I<ro> (for read
410 only). These will create either a read/write accessor or a read-only
411 accessor respectively, using the same name as the C<$name> of the attribute.
413 If you need more control over how your accessors are named, you can use the
414 I<reader>, I<writer> and I<accessor> options inherited from
415 L<Class::MOP::Attribute>.
417 =item I<isa =E<gt> $type_name>
419 The I<isa> option uses Moose's type constraint facilities to set up runtime
420 type checking for this attribute. Moose will perform the checks during class
421 construction, and within any accessors. The C<$type_name> argument must be a
422 string. The string may be either a class name or a type defined using
423 Moose's type definition features. (Refer to L<Moose::Util::TypeConstraints>
424 for information on how to define a new type, and how to retrieve type meta-data).
426 =item I<coerce =E<gt> (1|0)>
428 This will attempt to use coercion with the supplied type constraint to change
429 the value passed into any accessors or constructors. You B<must> have supplied
430 a type constraint in order for this to work. See L<Moose::Cookbook::Recipe5>
433 =item I<does =E<gt> $role_name>
435 This will accept the name of a role which the value stored in this attribute
436 is expected to have consumed.
438 =item I<required =E<gt> (1|0)>
440 This marks the attribute as being required. This means a I<defined> value must be
441 supplied during class construction, and the attribute may never be set to
442 C<undef> with an accessor.
444 =item I<weak_ref =E<gt> (1|0)>
446 This will tell the class to store the value of this attribute as a weakened
447 reference. If an attribute is a weakened reference, it B<cannot> also be
450 =item I<lazy =E<gt> (1|0)>
452 This will tell the class to not create this slot until absolutely necessary.
453 If an attribute is marked as lazy it B<must> have a default supplied.
455 =item I<auto_deref =E<gt> (1|0)>
457 This tells the accessor whether to automatically dereference the value returned.
458 This is only legal if your C<isa> option is either C<ArrayRef> or C<HashRef>.
460 =item I<metaclass =E<gt> $metaclass_name>
462 This tells the class to use a custom attribute metaclass for this particular
463 attribute. Custom attribute metaclasses are useful for extending the
464 capabilities of the I<has> keyword: they are the simplest way to extend the MOP,
465 but they are still a fairly advanced topic and too much to cover here. I will
466 try and write a recipe on them soon.
468 The default behavior here is to just load C<$metaclass_name>; however, we also
469 have a way to alias to a shorter name. This will first look to see if
470 B<Moose::Meta::Attribute::Custom::$metaclass_name> exists. If it does, Moose
471 will then check to see if that has the method C<register_implementation>, which
472 should return the actual name of the custom attribute metaclass. If there is no
473 C<register_implementation> method, it will fall back to using
474 B<Moose::Meta::Attribute::Custom::$metaclass_name> as the metaclass name.
476 =item I<trigger =E<gt> $code>
478 The I<trigger> option is a CODE reference which will be called after the value of
479 the attribute is set. The CODE ref will be passed the instance itself, the
480 updated value and the attribute meta-object (this is for more advanced fiddling
481 and can typically be ignored). You B<cannot> have a trigger on a read-only
484 =item I<handles =E<gt> ARRAY | HASH | REGEXP | ROLE | CODE>
486 The I<handles> option provides Moose classes with automated delegation features.
487 This is a pretty complex and powerful option. It accepts many different option
488 formats, each with its own benefits and drawbacks.
490 B<NOTE:> This feature is no longer experimental, but it may still have subtle
491 bugs lurking in the deeper corners. If you think you have found a bug, you
492 probably have, so please report it to me right away.
494 B<NOTE:> The class being delegated to does not need to be a Moose based class,
495 which is why this feature is especially useful when wrapping non-Moose classes.
497 All I<handles> option formats share the following traits:
499 You cannot override a locally defined method with a delegated method; an
500 exception will be thrown if you try. That is to say, if you define C<foo> in
501 your class, you cannot override it with a delegated C<foo>. This is almost never
502 something you would want to do, and if it is, you should do it by hand and not
505 You cannot override any of the methods found in Moose::Object, or the C<BUILD>
506 and C<DEMOLISH> methods. These will not throw an exception, but will silently
507 move on to the next method in the list. My reasoning for this is that you would
508 almost never want to do this, since it usually breaks your class. As with
509 overriding locally defined methods, if you do want to do this, you should do it
510 manually, not with Moose.
512 You do not I<need> to have a reader (or accessor) for the attribute in order
513 to delegate to it. Moose will create a means of accessing the value for you,
514 however this will be several times B<less> efficient then if you had given
515 the attribute a reader (or accessor) to use.
517 Below is the documentation for each option format:
523 This is the most common usage for I<handles>. You basically pass a list of
524 method names to be delegated, and Moose will install a delegation method
529 This is the second most common usage for I<handles>. Instead of a list of
530 method names, you pass a HASH ref where each key is the method name you
531 want installed locally, and its value is the name of the original method
532 in the class being delegated to.
534 This can be very useful for recursive classes like trees. Here is a
535 quick example (soon to be expanded into a Moose::Cookbook::Recipe):
540 has 'node' => (is => 'rw', isa => 'Any');
545 default => sub { [] }
553 parent_node => 'node',
554 siblings => 'children',
558 In this example, the Tree package gets C<parent_node> and C<siblings> methods,
559 which delegate to the C<node> and C<children> methods (respectively) of the Tree
560 instance stored in the C<parent> slot.
564 The regexp option works very similar to the ARRAY option, except that it builds
565 the list of methods for you. It starts by collecting all possible methods of the
566 class being delegated to, then filters that list using the regexp supplied here.
568 B<NOTE:> An I<isa> option is required when using the regexp option format. This
569 is so that we can determine (at compile time) the method list from the class.
570 Without an I<isa> this is just not possible.
574 With the role option, you specify the name of a role whose "interface" then
575 becomes the list of methods to handle. The "interface" can be defined as; the
576 methods of the role and any required methods of the role. It should be noted
577 that this does B<not> include any method modifiers or generated attribute
578 methods (which is consistent with role composition).
582 This is the option to use when you really want to do something funky. You should
583 only use it if you really know what you are doing, as it involves manual
586 This takes a code reference, which should expect two arguments. The first is the
587 attribute meta-object this I<handles> is attached to. The second is the
588 metaclass of the class being delegated to. It expects you to return a hash (not
589 a HASH ref) of the methods you want mapped.
595 =item B<has +$name =E<gt> %options>
597 This is variation on the normal attibute creator C<has> which allows you to
598 clone and extend an attribute from a superclass. Here is a quick example:
606 default => 'Hello, I am a Foo'
614 has '+message' => (default => 'Hello I am My::Foo');
616 What is happening here is that B<My::Foo> is cloning the C<message> attribute
617 from its parent class B<Foo>, retaining the C<is =E<gt> 'rw'> and C<isa =E<gt>
618 'Str'> characteristics, but changing the value in C<default>.
620 This feature is restricted somewhat, so as to try and force at least I<some>
621 sanity into it. You are only allowed to change the following attributes:
627 Change the default value of an attribute.
631 Change whether the attribute attempts to coerce a value passed to it.
635 Change if the attribute is required to have a value.
637 =item I<documentation>
639 Change the documentation string associated with the attribute.
643 Change if the attribute lazily initializes the slot.
647 You I<are> allowed to change the type, B<if and only if> the new type is a
648 subtype of the old type.
652 You are allowed to B<add> a new C<handles> definition, but you are B<not>
653 allowed to I<change> one.
657 =item B<before $name|@names =E<gt> sub { ... }>
659 =item B<after $name|@names =E<gt> sub { ... }>
661 =item B<around $name|@names =E<gt> sub { ... }>
663 This three items are syntactic sugar for the before, after, and around method
664 modifier features that L<Class::MOP> provides. More information on these may be
665 found in the L<Class::MOP::Class documentation|Class::MOP::Class/"Method
670 The keyword C<super> is a no-op when called outside of an C<override> method. In
671 the context of an C<override> method, it will call the next most appropriate
672 superclass method with the same arguments as the original method.
674 =item B<override ($name, &sub)>
676 An C<override> method is a way of explicitly saying "I am overriding this
677 method from my superclass". You can call C<super> within this method, and
678 it will work as expected. The same thing I<can> be accomplished with a normal
679 method call and the C<SUPER::> pseudo-package; it is really your choice.
683 The keyword C<inner>, much like C<super>, is a no-op outside of the context of
684 an C<augment> method. You can think of C<inner> as being the inverse of
685 C<super>; the details of how C<inner> and C<augment> work is best described in
686 the L<Moose::Cookbook>.
688 =item B<augment ($name, &sub)>
690 An C<augment> method, is a way of explicitly saying "I am augmenting this
691 method from my superclass". Once again, the details of how C<inner> and
692 C<augment> work is best described in the L<Moose::Cookbook>.
696 This is the C<Carp::confess> function, and exported here because I use it
697 all the time. This feature may change in the future, so you have been warned.
701 This is the C<Scalar::Util::blessed> function, it is exported here because I
702 use it all the time. It is highly recommended that this is used instead of
703 C<ref> anywhere you need to test for an object's class name.
707 =head1 UNIMPORTING FUNCTIONS
711 Moose offers a way to remove the keywords it exports, through the C<unimport>
712 method. You simply have to say C<no Moose> at the bottom of your code for this
713 to work. Here is an example:
718 has 'first_name' => (is => 'rw', isa => 'Str');
719 has 'last_name' => (is => 'rw', isa => 'Str');
723 $self->first_name . ' ' . $self->last_name
726 no Moose; # keywords are removed from the Person package
728 =head1 EXTENDING AND EMBEDDING MOOSE
730 Moose also offers some options for extending or embedding it into your own
731 framework. The basic premise is to have something that sets up your class'
732 metaclass and export the moose declarators (C<has>, C<with>, C<extends>,...).
739 my $CALLER = caller();
744 # we should never export to main
745 return if $CALLER eq 'main';
746 Moose::init_meta( $CALLER, 'MyFramework::Base' );
747 Moose->import({into => $CALLER});
749 # Do my custom framework stuff
756 Moose's C<import> method supports the L<Sub::Exporter> form of C<{into =E<gt> $pkg}>
757 and C<{into_level =E<gt> 1}>
759 =head2 B<init_meta ($class, $baseclass, $metaclass)>
761 Moose does some boot strapping: it creates a metaclass object for your class,
762 and then injects a C<meta> accessor into your class to retrieve it. Then it
763 sets your baseclass to Moose::Object or the value you pass in unless you already
764 have one. This is all done via C<init_meta> which takes the name of your class
765 and optionally a baseclass and a metaclass as arguments.
773 It should be noted that C<super> and C<inner> B<cannot> be used in the same
774 method. However, they may be combined within the same class hierarchy; see
775 F<t/014_override_augment_inner_super.t> for an example.
777 The reason for this is that C<super> is only valid within a method
778 with the C<override> modifier, and C<inner> will never be valid within an
779 C<override> method. In fact, C<augment> will skip over any C<override> methods
780 when searching for its appropriate C<inner>.
782 This might seem like a restriction, but I am of the opinion that keeping these
783 two features separate (yet interoperable) actually makes them easy to use, since
784 their behavior is then easier to predict. Time will tell whether I am right or
785 not (UPDATE: so far so good).
789 =head1 ACKNOWLEDGEMENTS
793 =item I blame Sam Vilain for introducing me to the insanity that is meta-models.
795 =item I blame Audrey Tang for then encouraging my meta-model habit in #perl6.
797 =item Without Yuval "nothingmuch" Kogman this module would not be possible,
798 and it certainly wouldn't have this name ;P
800 =item The basis of the TypeContraints module was Rob Kinyon's idea
801 originally, I just ran with it.
803 =item Thanks to mst & chansen and the whole #moose poose for all the
804 early ideas/feature-requests/encouragement/bug-finding.
806 =item Thanks to David "Theory" Wheeler for meta-discussions and spelling fixes.
814 =item L<http://www.iinteractive.com/moose>
816 This is the official web home of Moose, it contains links to our public SVN repo
817 as well as links to a number of talks and articles on Moose and Moose related
820 =item L<Class::MOP> documentation
822 =item The #moose channel on irc.perl.org
824 =item The Moose mailing list - moose@perl.org
826 =item Moose stats on ohloh.net - L<http://www.ohloh.net/projects/5788>
828 =item Several Moose extension modules in the L<MooseX::> namespace.
836 =item L<http://www.cs.utah.edu/plt/publications/oopsla04-gff.pdf>
838 This paper (suggested by lbr on #moose) was what lead to the implementation
839 of the C<super>/C<override> and C<inner>/C<augment> features. If you really
840 want to understand them, I suggest you read this.
846 All complex software has bugs lurking in it, and this module is no
847 exception. If you find a bug please either email me, or add the bug
852 Stevan Little E<lt>stevan@iinteractive.comE<gt>
854 B<with contributions from:>
860 Anders (Debolaz) Nor Berle
862 Nathan (kolibre) Gray
864 Christian (chansen) Hansen
866 Hans Dieter (confound) Pearcey
868 Eric (ewilhelm) Wilhelm
870 Guillermo (groditi) Roditi
872 Jess (castaway) Robinson
876 Robert (phaylon) Sedlacek
880 Scott (konobi) McWhirter
882 Shlomi (rindolf) Fish
884 Yuval (nothingmuch) Kogman
886 Chris (perigrin) Prather
888 Jonathan (jrockway) Rockway
890 Piotr (dexter) Roszatycki
896 ... and many other #moose folks
898 =head1 COPYRIGHT AND LICENSE
900 Copyright 2006-2008 by Infinity Interactive, Inc.
902 L<http://www.iinteractive.com>
904 This library is free software; you can redistribute it and/or modify
905 it under the same terms as Perl itself.