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 );
170 return subname 'Moose::metaclass' => sub {
174 make_immutable => sub {
176 return subname 'Moose::make_immutable' => sub {
177 warn "Use of make_immutable() is deprecated, please use metaclass->make_immutable now\n";
178 $class->meta->make_immutable(@_);
182 return \&Carp::confess;
185 return \&Scalar::Util::blessed;
189 my $exporter = Sub::Exporter::build_exporter(
191 exports => \%exports,
192 groups => { default => [':all'] }
196 # 1 extra level because it's called by import so there's a layer of indirection
200 ref $_[1] && defined $_[1]->{into}
202 : ref $_[1] && defined $_[1]->{into_level}
203 ? caller($offset + $_[1]->{into_level})
208 $CALLER = _get_caller(@_);
210 # this works because both pragmas set $^H (see perldoc perlvar)
211 # which affects the current compilation - i.e. the file who use'd
212 # us - which is why we don't need to do anything special to make
213 # it affect that file rather than this one (which is already compiled)
218 # we should never export to main
219 return if $CALLER eq 'main';
221 init_meta( $CALLER, 'Moose::Object' );
228 my $class = _get_caller(@_);
230 # loop through the exports ...
231 foreach my $name ( keys %exports ) {
234 if ( defined &{ $class . '::' . $name } ) {
235 my $keyword = \&{ $class . '::' . $name };
237 # make sure it is from Moose
238 my ($pkg_name) = Class::MOP::get_code_info($keyword);
240 next if $pkg_name ne 'Moose';
242 # and if it is from Moose then undef the slot
243 delete ${ $class . '::' }{$name};
250 ## make 'em all immutable
252 $_->meta->make_immutable(
253 inline_constructor => 0,
254 inline_accessors => 1, # these are Class::MOP accessors, so they need inlining
257 'Moose::Meta::Attribute',
258 'Moose::Meta::Class',
259 'Moose::Meta::Instance',
261 'Moose::Meta::TypeConstraint',
262 'Moose::Meta::TypeConstraint::Union',
263 'Moose::Meta::TypeConstraint::Parameterized',
264 'Moose::Meta::TypeCoercion',
266 'Moose::Meta::Method',
267 'Moose::Meta::Method::Accessor',
268 'Moose::Meta::Method::Constructor',
269 'Moose::Meta::Method::Destructor',
270 'Moose::Meta::Method::Overriden',
273 'Moose::Meta::Role::Method',
274 'Moose::Meta::Role::Method::Required',
285 Moose - A postmodern object system for Perl 5
290 use Moose; # automatically turns on strict and warnings
292 has 'x' => (is => 'rw', isa => 'Int');
293 has 'y' => (is => 'rw', isa => 'Int');
306 has 'z' => (is => 'rw', isa => 'Int');
308 after 'clear' => sub {
315 Moose is an extension of the Perl 5 object system.
317 =head2 Another object system!?!?
319 Yes, I know there has been an explosion recently of new ways to
320 build object's in Perl 5, most of them based on inside-out objects
321 and other such things. Moose is different because it is not a new
322 object system for Perl 5, but instead an extension of the existing
325 Moose is built on top of L<Class::MOP>, which is a metaclass system
326 for Perl 5. This means that Moose not only makes building normal
327 Perl 5 objects better, but it also provides the power of metaclass
330 =head2 Is this for real? Or is this just an experiment?
332 Moose is I<based> on the prototypes and experiments I did for the Perl 6
333 meta-model. However, Moose is B<NOT> an experiment/prototype; it is for B<real>.
335 =head2 Is this ready for use in production?
337 Yes, I believe that it is.
339 Moose has been used successfully in production environemnts by several people
340 and companies (including the one I work for). There are Moose applications
341 which have been in production with little or no issue now for well over a year.
342 I consider it highly stable and we are commited to keeping it stable.
344 Of course, in the end, you need to make this call yourself. If you have
345 any questions or concerns, please feel free to email me, or even the list
346 or just stop by #moose and ask away.
348 =head2 Is Moose just Perl 6 in Perl 5?
350 No. While Moose is very much inspired by Perl 6, it is not itself Perl 6.
351 Instead, it is an OO system for Perl 5. I built Moose because I was tired of
352 writing the same old boring Perl 5 OO code, and drooling over Perl 6 OO. So
353 instead of switching to Ruby, I wrote Moose :)
355 =head2 Wait, I<post> modern, I thought it was just I<modern>?
357 So I was reading Larry Wall's talk from the 1999 Linux World entitled
358 "Perl, the first postmodern computer language" in which he talks about how
359 he picked the features for Perl because he thought they were cool and he
360 threw out the ones that he thought sucked. This got me thinking about how
361 we have done the same thing in Moose. For Moose, we have "borrowed" features
362 from Perl 6, CLOS (LISP), Smalltalk, Java, BETA, OCaml, Ruby and more, and
363 the bits we didn't like (cause they sucked) we tossed aside. So for this
364 reason (and a few others) I have re-dubbed Moose a I<postmodern> object system.
368 =head2 Moose Extensions
370 The L<MooseX::> namespace is the official place to find Moose extensions.
371 There are a number of these modules out on CPAN right now the best way to
372 find them is to search for MooseX:: on search.cpan.org.
374 =head1 BUILDING CLASSES WITH MOOSE
376 Moose makes every attempt to provide as much convenience as possible during
377 class construction/definition, but still stay out of your way if you want it
378 to. Here are a few items to note when building classes with Moose.
380 Unless specified with C<extends>, any class which uses Moose will
381 inherit from L<Moose::Object>.
383 Moose will also manage all attributes (including inherited ones) that are
384 defined with C<has>. And (assuming you call C<new>, which is inherited from
385 L<Moose::Object>) this includes properly initializing all instance slots,
386 setting defaults where appropriate, and performing any type constraint checking
389 =head1 EXPORTED FUNCTIONS
391 Moose will export a number of functions into the class's namespace which
392 may then be used to set up the class. These functions all work directly
393 on the current class.
399 This is a method which provides access to the current class's metaclass.
401 =item B<extends (@superclasses)>
403 This function will set the superclass(es) for the current class.
405 This approach is recommended instead of C<use base>, because C<use base>
406 actually C<push>es onto the class's C<@ISA>, whereas C<extends> will
407 replace it. This is important to ensure that classes which do not have
408 superclasses still properly inherit from L<Moose::Object>.
410 =item B<with (@roles)>
412 This will apply a given set of C<@roles> to the local class. Role support
413 is currently under heavy development; see L<Moose::Role> for more details.
415 =item B<has $name =E<gt> %options>
417 This will install an attribute of a given C<$name> into the current class.
418 The C<%options> are the same as those provided by
419 L<Class::MOP::Attribute>, in addition to the list below which are provided
420 by Moose (L<Moose::Meta::Attribute> to be more specific):
424 =item I<is =E<gt> 'rw'|'ro'>
426 The I<is> option accepts either I<rw> (for read/write) or I<ro> (for read
427 only). These will create either a read/write accessor or a read-only
428 accessor respectively, using the same name as the C<$name> of the attribute.
430 If you need more control over how your accessors are named, you can use the
431 I<reader>, I<writer> and I<accessor> options inherited from
432 L<Class::MOP::Attribute>.
434 =item I<isa =E<gt> $type_name>
436 The I<isa> option uses Moose's type constraint facilities to set up runtime
437 type checking for this attribute. Moose will perform the checks during class
438 construction, and within any accessors. The C<$type_name> argument must be a
439 string. The string may be either a class name or a type defined using
440 Moose's type definition features. (Refer to L<Moose::Util::TypeConstraints>
441 for information on how to define a new type, and how to retrieve type meta-data).
443 =item I<coerce =E<gt> (1|0)>
445 This will attempt to use coercion with the supplied type constraint to change
446 the value passed into any accessors or constructors. You B<must> have supplied
447 a type constraint in order for this to work. See L<Moose::Cookbook::Recipe5>
450 =item I<does =E<gt> $role_name>
452 This will accept the name of a role which the value stored in this attribute
453 is expected to have consumed.
455 =item I<required =E<gt> (1|0)>
457 This marks the attribute as being required. This means a I<defined> value must be
458 supplied during class construction, and the attribute may never be set to
459 C<undef> with an accessor.
461 =item I<weak_ref =E<gt> (1|0)>
463 This will tell the class to store the value of this attribute as a weakened
464 reference. If an attribute is a weakened reference, it B<cannot> also be
467 =item I<lazy =E<gt> (1|0)>
469 This will tell the class to not create this slot until absolutely necessary.
470 If an attribute is marked as lazy it B<must> have a default supplied.
472 =item I<auto_deref =E<gt> (1|0)>
474 This tells the accessor whether to automatically dereference the value returned.
475 This is only legal if your C<isa> option is either C<ArrayRef> or C<HashRef>.
477 =item I<metaclass =E<gt> $metaclass_name>
479 This tells the class to use a custom attribute metaclass for this particular
480 attribute. Custom attribute metaclasses are useful for extending the
481 capabilities of the I<has> keyword: they are the simplest way to extend the MOP,
482 but they are still a fairly advanced topic and too much to cover here. I will
483 try and write a recipe on them soon.
485 The default behavior here is to just load C<$metaclass_name>; however, we also
486 have a way to alias to a shorter name. This will first look to see if
487 B<Moose::Meta::Attribute::Custom::$metaclass_name> exists. If it does, Moose
488 will then check to see if that has the method C<register_implementation>, which
489 should return the actual name of the custom attribute metaclass. If there is no
490 C<register_implementation> method, it will fall back to using
491 B<Moose::Meta::Attribute::Custom::$metaclass_name> as the metaclass name.
493 =item I<trigger =E<gt> $code>
495 The I<trigger> option is a CODE reference which will be called after the value of
496 the attribute is set. The CODE ref will be passed the instance itself, the
497 updated value and the attribute meta-object (this is for more advanced fiddling
498 and can typically be ignored). You B<cannot> have a trigger on a read-only
501 =item I<handles =E<gt> ARRAY | HASH | REGEXP | ROLE | CODE>
503 The I<handles> option provides Moose classes with automated delegation features.
504 This is a pretty complex and powerful option. It accepts many different option
505 formats, each with its own benefits and drawbacks.
507 B<NOTE:> This feature is no longer experimental, but it may still have subtle
508 bugs lurking in the deeper corners. If you think you have found a bug, you
509 probably have, so please report it to me right away.
511 B<NOTE:> The class being delegated to does not need to be a Moose based class,
512 which is why this feature is especially useful when wrapping non-Moose classes.
514 All I<handles> option formats share the following traits:
516 You cannot override a locally defined method with a delegated method; an
517 exception will be thrown if you try. That is to say, if you define C<foo> in
518 your class, you cannot override it with a delegated C<foo>. This is almost never
519 something you would want to do, and if it is, you should do it by hand and not
522 You cannot override any of the methods found in Moose::Object, or the C<BUILD>
523 and C<DEMOLISH> methods. These will not throw an exception, but will silently
524 move on to the next method in the list. My reasoning for this is that you would
525 almost never want to do this, since it usually breaks your class. As with
526 overriding locally defined methods, if you do want to do this, you should do it
527 manually, not with Moose.
529 You do not I<need> to have a reader (or accessor) for the attribute in order
530 to delegate to it. Moose will create a means of accessing the value for you,
531 however this will be several times B<less> efficient then if you had given
532 the attribute a reader (or accessor) to use.
534 Below is the documentation for each option format:
540 This is the most common usage for I<handles>. You basically pass a list of
541 method names to be delegated, and Moose will install a delegation method
546 This is the second most common usage for I<handles>. Instead of a list of
547 method names, you pass a HASH ref where each key is the method name you
548 want installed locally, and its value is the name of the original method
549 in the class being delegated to.
551 This can be very useful for recursive classes like trees. Here is a
552 quick example (soon to be expanded into a Moose::Cookbook::Recipe):
557 has 'node' => (is => 'rw', isa => 'Any');
562 default => sub { [] }
570 parent_node => 'node',
571 siblings => 'children',
575 In this example, the Tree package gets C<parent_node> and C<siblings> methods,
576 which delegate to the C<node> and C<children> methods (respectively) of the Tree
577 instance stored in the C<parent> slot.
581 The regexp option works very similar to the ARRAY option, except that it builds
582 the list of methods for you. It starts by collecting all possible methods of the
583 class being delegated to, then filters that list using the regexp supplied here.
585 B<NOTE:> An I<isa> option is required when using the regexp option format. This
586 is so that we can determine (at compile time) the method list from the class.
587 Without an I<isa> this is just not possible.
591 With the role option, you specify the name of a role whose "interface" then
592 becomes the list of methods to handle. The "interface" can be defined as; the
593 methods of the role and any required methods of the role. It should be noted
594 that this does B<not> include any method modifiers or generated attribute
595 methods (which is consistent with role composition).
599 This is the option to use when you really want to do something funky. You should
600 only use it if you really know what you are doing, as it involves manual
603 This takes a code reference, which should expect two arguments. The first is the
604 attribute meta-object this I<handles> is attached to. The second is the
605 metaclass of the class being delegated to. It expects you to return a hash (not
606 a HASH ref) of the methods you want mapped.
612 =item B<has +$name =E<gt> %options>
614 This is variation on the normal attibute creator C<has> which allows you to
615 clone and extend an attribute from a superclass or from a role. Here is an
616 example of the superclass usage:
624 default => 'Hello, I am a Foo'
632 has '+message' => (default => 'Hello I am My::Foo');
634 What is happening here is that B<My::Foo> is cloning the C<message> attribute
635 from its parent class B<Foo>, retaining the C<is =E<gt> 'rw'> and C<isa =E<gt>
636 'Str'> characteristics, but changing the value in C<default>.
638 Here is another example, but within the context of a role:
646 default => 'Hello, I am a Foo'
654 has '+message' => (default => 'Hello I am My::Foo');
656 In this case, we are basically taking the attribute which the role supplied
657 and altering it within the bounds of this feature.
659 Aside from where the attributes come from (one from superclass, the other
660 from a role), this feature works exactly the same. This feature is restricted
661 somewhat, so as to try and force at least I<some> sanity into it. You are only
662 allowed to change the following attributes:
668 Change the default value of an attribute.
672 Change whether the attribute attempts to coerce a value passed to it.
676 Change if the attribute is required to have a value.
678 =item I<documentation>
680 Change the documentation string associated with the attribute.
684 Change if the attribute lazily initializes the slot.
688 You I<are> allowed to change the type, B<if and only if> the new type is a
689 subtype of the old type.
693 You are allowed to B<add> a new C<handles> definition, but you are B<not>
694 allowed to I<change> one.
698 You are allowed to B<add> a new C<builder> definition, but you are B<not>
699 allowed to I<change> one.
703 =item B<before $name|@names =E<gt> sub { ... }>
705 =item B<after $name|@names =E<gt> sub { ... }>
707 =item B<around $name|@names =E<gt> sub { ... }>
709 This three items are syntactic sugar for the before, after, and around method
710 modifier features that L<Class::MOP> provides. More information on these may be
711 found in the L<Class::MOP::Class documentation|Class::MOP::Class/"Method
716 The keyword C<super> is a no-op when called outside of an C<override> method. In
717 the context of an C<override> method, it will call the next most appropriate
718 superclass method with the same arguments as the original method.
720 =item B<override ($name, &sub)>
722 An C<override> method is a way of explicitly saying "I am overriding this
723 method from my superclass". You can call C<super> within this method, and
724 it will work as expected. The same thing I<can> be accomplished with a normal
725 method call and the C<SUPER::> pseudo-package; it is really your choice.
729 The keyword C<inner>, much like C<super>, is a no-op outside of the context of
730 an C<augment> method. You can think of C<inner> as being the inverse of
731 C<super>; the details of how C<inner> and C<augment> work is best described in
732 the L<Moose::Cookbook>.
734 =item B<augment ($name, &sub)>
736 An C<augment> method, is a way of explicitly saying "I am augmenting this
737 method from my superclass". Once again, the details of how C<inner> and
738 C<augment> work is best described in the L<Moose::Cookbook>.
742 This is the C<Carp::confess> function, and exported here because I use it
743 all the time. This feature may change in the future, so you have been warned.
747 This is the C<Scalar::Util::blessed> function, it is exported here because I
748 use it all the time. It is highly recommended that this is used instead of
749 C<ref> anywhere you need to test for an object's class name.
753 =head1 UNIMPORTING FUNCTIONS
757 Moose offers a way to remove the keywords it exports, through the C<unimport>
758 method. You simply have to say C<no Moose> at the bottom of your code for this
759 to work. Here is an example:
764 has 'first_name' => (is => 'rw', isa => 'Str');
765 has 'last_name' => (is => 'rw', isa => 'Str');
769 $self->first_name . ' ' . $self->last_name
772 no Moose; # keywords are removed from the Person package
774 =head1 EXTENDING AND EMBEDDING MOOSE
776 Moose also offers some options for extending or embedding it into your own
777 framework. The basic premise is to have something that sets up your class'
778 metaclass and export the moose declarators (C<has>, C<with>, C<extends>,...).
785 my $CALLER = caller();
790 # we should never export to main
791 return if $CALLER eq 'main';
792 Moose::init_meta( $CALLER, 'MyFramework::Base' );
793 Moose->import({into => $CALLER});
795 # Do my custom framework stuff
802 Moose's C<import> method supports the L<Sub::Exporter> form of C<{into =E<gt> $pkg}>
803 and C<{into_level =E<gt> 1}>
805 =head2 B<init_meta ($class, $baseclass, $metaclass)>
807 Moose does some boot strapping: it creates a metaclass object for your class,
808 and then injects a C<meta> accessor into your class to retrieve it. Then it
809 sets your baseclass to Moose::Object or the value you pass in unless you already
810 have one. This is all done via C<init_meta> which takes the name of your class
811 and optionally a baseclass and a metaclass as arguments.
819 It should be noted that C<super> and C<inner> B<cannot> be used in the same
820 method. However, they may be combined within the same class hierarchy; see
821 F<t/014_override_augment_inner_super.t> for an example.
823 The reason for this is that C<super> is only valid within a method
824 with the C<override> modifier, and C<inner> will never be valid within an
825 C<override> method. In fact, C<augment> will skip over any C<override> methods
826 when searching for its appropriate C<inner>.
828 This might seem like a restriction, but I am of the opinion that keeping these
829 two features separate (yet interoperable) actually makes them easy to use, since
830 their behavior is then easier to predict. Time will tell whether I am right or
831 not (UPDATE: so far so good).
835 =head1 ACKNOWLEDGEMENTS
839 =item I blame Sam Vilain for introducing me to the insanity that is meta-models.
841 =item I blame Audrey Tang for then encouraging my meta-model habit in #perl6.
843 =item Without Yuval "nothingmuch" Kogman this module would not be possible,
844 and it certainly wouldn't have this name ;P
846 =item The basis of the TypeContraints module was Rob Kinyon's idea
847 originally, I just ran with it.
849 =item Thanks to mst & chansen and the whole #moose poose for all the
850 early ideas/feature-requests/encouragement/bug-finding.
852 =item Thanks to David "Theory" Wheeler for meta-discussions and spelling fixes.
860 =item L<http://www.iinteractive.com/moose>
862 This is the official web home of Moose, it contains links to our public SVN repo
863 as well as links to a number of talks and articles on Moose and Moose related
866 =item L<Class::MOP> documentation
868 =item The #moose channel on irc.perl.org
870 =item The Moose mailing list - moose@perl.org
872 =item Moose stats on ohloh.net - L<http://www.ohloh.net/projects/5788>
874 =item Several Moose extension modules in the L<MooseX::> namespace.
882 =item L<http://www.cs.utah.edu/plt/publications/oopsla04-gff.pdf>
884 This paper (suggested by lbr on #moose) was what lead to the implementation
885 of the C<super>/C<override> and C<inner>/C<augment> features. If you really
886 want to understand them, I suggest you read this.
892 All complex software has bugs lurking in it, and this module is no
893 exception. If you find a bug please either email me, or add the bug
898 Stevan Little E<lt>stevan@iinteractive.comE<gt>
900 B<with contributions from:>
906 Anders (Debolaz) Nor Berle
908 Nathan (kolibre) Gray
910 Christian (chansen) Hansen
912 Hans Dieter (confound) Pearcey
914 Eric (ewilhelm) Wilhelm
916 Guillermo (groditi) Roditi
918 Jess (castaway) Robinson
922 Robert (phaylon) Sedlacek
926 Scott (konobi) McWhirter
928 Shlomi (rindolf) Fish
930 Yuval (nothingmuch) Kogman
932 Chris (perigrin) Prather
934 Jonathan (jrockway) Rockway
936 Piotr (dexter) Roszatycki
942 ... and many other #moose folks
944 =head1 COPYRIGHT AND LICENSE
946 Copyright 2006-2008 by Infinity Interactive, Inc.
948 L<http://www.iinteractive.com>
950 This library is free software; you can redistribute it and/or modify
951 it under the same terms as Perl itself.