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 @_;
87 foreach my $super (@supers) {
88 Class::MOP::load_class($super);
91 # this checks the metaclass to make sure
92 # it is correct, sometimes it can get out
93 # of sync when the classes are being built
94 my $meta = $class->meta->_fix_metaclass_incompatability(@supers);
95 $meta->superclasses(@supers);
100 return subname 'Moose::with' => sub (@) {
101 Moose::Util::apply_all_roles($class->meta, @_)
106 return subname 'Moose::has' => sub ($;%) {
108 die 'Usage: has \'name\' => ( key => value, ... )' if @_ == 1;
110 my $attrs = ( ref($name) eq 'ARRAY' ) ? $name : [ ($name) ];
111 $class->meta->add_attribute( $_, %options ) for @$attrs;
116 return subname 'Moose::before' => sub (@&) {
118 my $meta = $class->meta;
119 $meta->add_before_method_modifier( $_, $code ) for @_;
124 return subname 'Moose::after' => sub (@&) {
126 my $meta = $class->meta;
127 $meta->add_after_method_modifier( $_, $code ) for @_;
132 return subname 'Moose::around' => sub (@&) {
134 my $meta = $class->meta;
135 $meta->add_around_method_modifier( $_, $code ) for @_;
142 $SUPER_SLOT{$CALLER} = \*{"${CALLER}::super"};
144 return subname 'Moose::super' => sub { };
148 return subname 'Moose::override' => sub ($&) {
149 my ( $name, $method ) = @_;
150 $class->meta->add_override_method_modifier( $name => $method );
157 $INNER_SLOT{$CALLER} = \*{"${CALLER}::inner"};
159 return subname 'Moose::inner' => sub { };
163 return subname 'Moose::augment' => sub (@&) {
164 my ( $name, $method ) = @_;
165 $class->meta->add_augment_method_modifier( $name => $method );
168 make_immutable => sub {
170 return subname 'Moose::make_immutable' => sub {
171 $class->meta->make_immutable(@_);
175 return \&Carp::confess;
178 return \&Scalar::Util::blessed;
182 my $exporter = Sub::Exporter::build_exporter(
184 exports => \%exports,
185 groups => { default => [':all'] }
189 # 1 extra level because it's called by import so there's a layer of indirection
193 ref $_[1] && defined $_[1]->{into}
195 : ref $_[1] && defined $_[1]->{into_level}
196 ? caller($offset + $_[1]->{into_level})
201 $CALLER = _get_caller(@_);
203 # this works because both pragmas set $^H (see perldoc perlvar)
204 # which affects the current compilation - i.e. the file who use'd
205 # us - which is why we don't need to do anything special to make
206 # it affect that file rather than this one (which is already compiled)
211 # we should never export to main
212 return if $CALLER eq 'main';
214 init_meta( $CALLER, 'Moose::Object' );
221 my $class = _get_caller(@_);
223 # loop through the exports ...
224 foreach my $name ( keys %exports ) {
227 if ( defined &{ $class . '::' . $name } ) {
228 my $keyword = \&{ $class . '::' . $name };
230 # make sure it is from Moose
231 my ($pkg_name) = Class::MOP::get_code_info($keyword);
233 next if $pkg_name ne 'Moose';
235 # and if it is from Moose then undef the slot
236 delete ${ $class . '::' }{$name};
243 ## make 'em all immutable
245 $_->meta->make_immutable(
246 inline_constructor => 0,
247 inline_accessors => 1, # these are Class::MOP accessors, so they need inlining
250 'Moose::Meta::Attribute',
251 'Moose::Meta::Class',
252 'Moose::Meta::Instance',
254 'Moose::Meta::TypeConstraint',
255 'Moose::Meta::TypeConstraint::Union',
256 'Moose::Meta::TypeConstraint::Parameterized',
257 'Moose::Meta::TypeCoercion',
259 'Moose::Meta::Method',
260 'Moose::Meta::Method::Accessor',
261 'Moose::Meta::Method::Constructor',
262 'Moose::Meta::Method::Destructor',
263 'Moose::Meta::Method::Overriden',
266 'Moose::Meta::Role::Method',
267 'Moose::Meta::Role::Method::Required',
278 Moose - A postmodern object system for Perl 5
283 use Moose; # automatically turns on strict and warnings
285 has 'x' => (is => 'rw', isa => 'Int');
286 has 'y' => (is => 'rw', isa => 'Int');
299 has 'z' => (is => 'rw', isa => 'Int');
301 after 'clear' => sub {
308 Moose is an extension of the Perl 5 object system.
310 =head2 Another object system!?!?
312 Yes, I know there has been an explosion recently of new ways to
313 build object's in Perl 5, most of them based on inside-out objects
314 and other such things. Moose is different because it is not a new
315 object system for Perl 5, but instead an extension of the existing
318 Moose is built on top of L<Class::MOP>, which is a metaclass system
319 for Perl 5. This means that Moose not only makes building normal
320 Perl 5 objects better, but it also provides the power of metaclass
323 =head2 Is this for real? Or is this just an experiment?
325 Moose is I<based> on the prototypes and experiments I did for the Perl 6
326 meta-model. However, Moose is B<NOT> an experiment/prototype; it is for B<real>.
328 =head2 Is this ready for use in production?
330 Yes, I believe that it is.
332 Moose has been used successfully in production environemnts by several people
333 and companies (including the one I work for). There are Moose applications
334 which have been in production with little or no issue now for well over a year.
335 I consider it highly stable and we are commited to keeping it stable.
337 Of course, in the end, you need to make this call yourself. If you have
338 any questions or concerns, please feel free to email me, or even the list
339 or just stop by #moose and ask away.
341 =head2 Is Moose just Perl 6 in Perl 5?
343 No. While Moose is very much inspired by Perl 6, it is not itself Perl 6.
344 Instead, it is an OO system for Perl 5. I built Moose because I was tired of
345 writing the same old boring Perl 5 OO code, and drooling over Perl 6 OO. So
346 instead of switching to Ruby, I wrote Moose :)
348 =head2 Wait, I<post> modern, I thought it was just I<modern>?
350 So I was reading Larry Wall's talk from the 1999 Linux World entitled
351 "Perl, the first postmodern computer language" in which he talks about how
352 he picked the features for Perl because he thought they were cool and he
353 threw out the ones that he thought sucked. This got me thinking about how
354 we have done the same thing in Moose. For Moose, we have "borrowed" features
355 from Perl 6, CLOS (LISP), Smalltalk, Java, BETA, OCaml, Ruby and more, and
356 the bits we didn't like (cause they sucked) we tossed aside. So for this
357 reason (and a few others) I have re-dubbed Moose a I<postmodern> object system.
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::$metaclass_name> exists. If it does, Moose
481 will then check to see if that has the method C<register_implementation>, which
482 should return the actual name of the custom attribute metaclass. If there is no
483 C<register_implementation> method, it will fall back to using
484 B<Moose::Meta::Attribute::Custom::$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 You do not I<need> to have a reader (or accessor) for the attribute in order
523 to delegate to it. Moose will create a means of accessing the value for you,
524 however this will be several times B<less> efficient then if you had given
525 the attribute a reader (or accessor) to use.
527 Below is the documentation for each option format:
533 This is the most common usage for I<handles>. You basically pass a list of
534 method names to be delegated, and Moose will install a delegation method
539 This is the second most common usage for I<handles>. Instead of a list of
540 method names, you pass a HASH ref where each key is the method name you
541 want installed locally, and its value is the name of the original method
542 in the class being delegated to.
544 This can be very useful for recursive classes like trees. Here is a
545 quick example (soon to be expanded into a Moose::Cookbook::Recipe):
550 has 'node' => (is => 'rw', isa => 'Any');
555 default => sub { [] }
563 parent_node => 'node',
564 siblings => 'children',
568 In this example, the Tree package gets C<parent_node> and C<siblings> methods,
569 which delegate to the C<node> and C<children> methods (respectively) of the Tree
570 instance stored in the C<parent> slot.
574 The regexp option works very similar to the ARRAY option, except that it builds
575 the list of methods for you. It starts by collecting all possible methods of the
576 class being delegated to, then filters that list using the regexp supplied here.
578 B<NOTE:> An I<isa> option is required when using the regexp option format. This
579 is so that we can determine (at compile time) the method list from the class.
580 Without an I<isa> this is just not possible.
584 With the role option, you specify the name of a role whose "interface" then
585 becomes the list of methods to handle. The "interface" can be defined as; the
586 methods of the role and any required methods of the role. It should be noted
587 that this does B<not> include any method modifiers or generated attribute
588 methods (which is consistent with role composition).
592 This is the option to use when you really want to do something funky. You should
593 only use it if you really know what you are doing, as it involves manual
596 This takes a code reference, which should expect two arguments. The first is the
597 attribute meta-object this I<handles> is attached to. The second is the
598 metaclass of the class being delegated to. It expects you to return a hash (not
599 a HASH ref) of the methods you want mapped.
605 =item B<has +$name =E<gt> %options>
607 This is variation on the normal attibute creator C<has> which allows you to
608 clone and extend an attribute from a superclass or from a role. Here is an
609 example of the superclass usage:
617 default => 'Hello, I am a Foo'
625 has '+message' => (default => 'Hello I am My::Foo');
627 What is happening here is that B<My::Foo> is cloning the C<message> attribute
628 from its parent class B<Foo>, retaining the C<is =E<gt> 'rw'> and C<isa =E<gt>
629 'Str'> characteristics, but changing the value in C<default>.
631 Here is another example, but within the context of a role:
639 default => 'Hello, I am a Foo'
647 has '+message' => (default => 'Hello I am My::Foo');
649 In this case, we are basically taking the attribute which the role supplied
650 and altering it within the bounds of this feature.
652 Aside from where the attributes come from (one from superclass, the other
653 from a role), this feature works exactly the same. This feature is restricted
654 somewhat, so as to try and force at least I<some> sanity into it. You are only
655 allowed to change the following attributes:
661 Change the default value of an attribute.
665 Change whether the attribute attempts to coerce a value passed to it.
669 Change if the attribute is required to have a value.
671 =item I<documentation>
673 Change the documentation string associated with the attribute.
677 Change if the attribute lazily initializes the slot.
681 You I<are> allowed to change the type, B<if and only if> the new type is a
682 subtype of the old type.
686 You are allowed to B<add> a new C<handles> definition, but you are B<not>
687 allowed to I<change> one.
691 You are allowed to B<add> a new C<builder> definition, but you are B<not>
692 allowed to I<change> one.
696 =item B<before $name|@names =E<gt> sub { ... }>
698 =item B<after $name|@names =E<gt> sub { ... }>
700 =item B<around $name|@names =E<gt> sub { ... }>
702 This three items are syntactic sugar for the before, after, and around method
703 modifier features that L<Class::MOP> provides. More information on these may be
704 found in the L<Class::MOP::Class documentation|Class::MOP::Class/"Method
709 The keyword C<super> is a no-op when called outside of an C<override> method. In
710 the context of an C<override> method, it will call the next most appropriate
711 superclass method with the same arguments as the original method.
713 =item B<override ($name, &sub)>
715 An C<override> method is a way of explicitly saying "I am overriding this
716 method from my superclass". You can call C<super> within this method, and
717 it will work as expected. The same thing I<can> be accomplished with a normal
718 method call and the C<SUPER::> pseudo-package; it is really your choice.
722 The keyword C<inner>, much like C<super>, is a no-op outside of the context of
723 an C<augment> method. You can think of C<inner> as being the inverse of
724 C<super>; the details of how C<inner> and C<augment> work is best described in
725 the L<Moose::Cookbook>.
727 =item B<augment ($name, &sub)>
729 An C<augment> method, is a way of explicitly saying "I am augmenting this
730 method from my superclass". Once again, the details of how C<inner> and
731 C<augment> work is best described in the L<Moose::Cookbook>.
735 This is the C<Carp::confess> function, and exported here because I use it
736 all the time. This feature may change in the future, so you have been warned.
740 This is the C<Scalar::Util::blessed> function, it is exported here because I
741 use it all the time. It is highly recommended that this is used instead of
742 C<ref> anywhere you need to test for an object's class name.
746 =head1 UNIMPORTING FUNCTIONS
750 Moose offers a way to remove the keywords it exports, through the C<unimport>
751 method. You simply have to say C<no Moose> at the bottom of your code for this
752 to work. Here is an example:
757 has 'first_name' => (is => 'rw', isa => 'Str');
758 has 'last_name' => (is => 'rw', isa => 'Str');
762 $self->first_name . ' ' . $self->last_name
765 no Moose; # keywords are removed from the Person package
767 =head1 EXTENDING AND EMBEDDING MOOSE
769 Moose also offers some options for extending or embedding it into your own
770 framework. The basic premise is to have something that sets up your class'
771 metaclass and export the moose declarators (C<has>, C<with>, C<extends>,...).
778 my $CALLER = caller();
783 # we should never export to main
784 return if $CALLER eq 'main';
785 Moose::init_meta( $CALLER, 'MyFramework::Base' );
786 Moose->import({into => $CALLER});
788 # Do my custom framework stuff
795 Moose's C<import> method supports the L<Sub::Exporter> form of C<{into =E<gt> $pkg}>
796 and C<{into_level =E<gt> 1}>
798 =head2 B<init_meta ($class, $baseclass, $metaclass)>
800 Moose does some boot strapping: it creates a metaclass object for your class,
801 and then injects a C<meta> accessor into your class to retrieve it. Then it
802 sets your baseclass to Moose::Object or the value you pass in unless you already
803 have one. This is all done via C<init_meta> which takes the name of your class
804 and optionally a baseclass and a metaclass as arguments.
812 It should be noted that C<super> and C<inner> B<cannot> be used in the same
813 method. However, they may be combined within the same class hierarchy; see
814 F<t/014_override_augment_inner_super.t> for an example.
816 The reason for this is that C<super> is only valid within a method
817 with the C<override> modifier, and C<inner> will never be valid within an
818 C<override> method. In fact, C<augment> will skip over any C<override> methods
819 when searching for its appropriate C<inner>.
821 This might seem like a restriction, but I am of the opinion that keeping these
822 two features separate (yet interoperable) actually makes them easy to use, since
823 their behavior is then easier to predict. Time will tell whether I am right or
824 not (UPDATE: so far so good).
828 =head1 ACKNOWLEDGEMENTS
832 =item I blame Sam Vilain for introducing me to the insanity that is meta-models.
834 =item I blame Audrey Tang for then encouraging my meta-model habit in #perl6.
836 =item Without Yuval "nothingmuch" Kogman this module would not be possible,
837 and it certainly wouldn't have this name ;P
839 =item The basis of the TypeContraints module was Rob Kinyon's idea
840 originally, I just ran with it.
842 =item Thanks to mst & chansen and the whole #moose poose for all the
843 early ideas/feature-requests/encouragement/bug-finding.
845 =item Thanks to David "Theory" Wheeler for meta-discussions and spelling fixes.
853 =item L<http://www.iinteractive.com/moose>
855 This is the official web home of Moose, it contains links to our public SVN repo
856 as well as links to a number of talks and articles on Moose and Moose related
859 =item L<Class::MOP> documentation
861 =item The #moose channel on irc.perl.org
863 =item The Moose mailing list - moose@perl.org
865 =item Moose stats on ohloh.net - L<http://www.ohloh.net/projects/5788>
867 =item Several Moose extension modules in the L<MooseX::> namespace.
875 =item L<http://www.cs.utah.edu/plt/publications/oopsla04-gff.pdf>
877 This paper (suggested by lbr on #moose) was what lead to the implementation
878 of the C<super>/C<override> and C<inner>/C<augment> features. If you really
879 want to understand them, I suggest you read this.
885 All complex software has bugs lurking in it, and this module is no
886 exception. If you find a bug please either email me, or add the bug
891 Stevan Little E<lt>stevan@iinteractive.comE<gt>
893 B<with contributions from:>
899 Anders (Debolaz) Nor Berle
901 Nathan (kolibre) Gray
903 Christian (chansen) Hansen
905 Hans Dieter (confound) Pearcey
907 Eric (ewilhelm) Wilhelm
909 Guillermo (groditi) Roditi
911 Jess (castaway) Robinson
915 Robert (phaylon) Sedlacek
919 Scott (konobi) McWhirter
921 Shlomi (rindolf) Fish
923 Yuval (nothingmuch) Kogman
925 Chris (perigrin) Prather
927 Jonathan (jrockway) Rockway
929 Piotr (dexter) Roszatycki
935 ... and many other #moose folks
937 =head1 COPYRIGHT AND LICENSE
939 Copyright 2006-2008 by Infinity Interactive, Inc.
941 L<http://www.iinteractive.com>
943 This library is free software; you can redistribute it and/or modify
944 it under the same terms as Perl itself.