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 warn "Use of make_immutable() is deprecated, please use metaclass->make_immutable now\n";
172 $class->meta->make_immutable(@_);
176 return \&Carp::confess;
179 return \&Scalar::Util::blessed;
183 my $exporter = Sub::Exporter::build_exporter(
185 exports => \%exports,
186 groups => { default => [':all'] }
190 # 1 extra level because it's called by import so there's a layer of indirection
194 ref $_[1] && defined $_[1]->{into}
196 : ref $_[1] && defined $_[1]->{into_level}
197 ? caller($offset + $_[1]->{into_level})
202 $CALLER = _get_caller(@_);
204 # this works because both pragmas set $^H (see perldoc perlvar)
205 # which affects the current compilation - i.e. the file who use'd
206 # us - which is why we don't need to do anything special to make
207 # it affect that file rather than this one (which is already compiled)
212 # we should never export to main
213 return if $CALLER eq 'main';
215 init_meta( $CALLER, 'Moose::Object' );
222 my $class = _get_caller(@_);
224 # loop through the exports ...
225 foreach my $name ( keys %exports ) {
228 if ( defined &{ $class . '::' . $name } ) {
229 my $keyword = \&{ $class . '::' . $name };
231 # make sure it is from Moose
232 my ($pkg_name) = Class::MOP::get_code_info($keyword);
234 next if $pkg_name ne 'Moose';
236 # and if it is from Moose then undef the slot
237 delete ${ $class . '::' }{$name};
244 ## make 'em all immutable
246 $_->meta->make_immutable(
247 inline_constructor => 0,
248 inline_accessors => 1, # these are Class::MOP accessors, so they need inlining
251 'Moose::Meta::Attribute',
252 'Moose::Meta::Class',
253 'Moose::Meta::Instance',
255 'Moose::Meta::TypeConstraint',
256 'Moose::Meta::TypeConstraint::Union',
257 'Moose::Meta::TypeConstraint::Parameterized',
258 'Moose::Meta::TypeCoercion',
260 'Moose::Meta::Method',
261 'Moose::Meta::Method::Accessor',
262 'Moose::Meta::Method::Constructor',
263 'Moose::Meta::Method::Destructor',
264 'Moose::Meta::Method::Overriden',
267 'Moose::Meta::Role::Method',
268 'Moose::Meta::Role::Method::Required',
279 Moose - A postmodern object system for Perl 5
284 use Moose; # automatically turns on strict and warnings
286 has 'x' => (is => 'rw', isa => 'Int');
287 has 'y' => (is => 'rw', isa => 'Int');
300 has 'z' => (is => 'rw', isa => 'Int');
302 after 'clear' => sub {
309 Moose is an extension of the Perl 5 object system.
311 =head2 Another object system!?!?
313 Yes, I know there has been an explosion recently of new ways to
314 build object's in Perl 5, most of them based on inside-out objects
315 and other such things. Moose is different because it is not a new
316 object system for Perl 5, but instead an extension of the existing
319 Moose is built on top of L<Class::MOP>, which is a metaclass system
320 for Perl 5. This means that Moose not only makes building normal
321 Perl 5 objects better, but it also provides the power of metaclass
324 =head2 Is this for real? Or is this just an experiment?
326 Moose is I<based> on the prototypes and experiments I did for the Perl 6
327 meta-model. However, Moose is B<NOT> an experiment/prototype; it is for B<real>.
329 =head2 Is this ready for use in production?
331 Yes, I believe that it is.
333 Moose has been used successfully in production environemnts by several people
334 and companies (including the one I work for). There are Moose applications
335 which have been in production with little or no issue now for well over a year.
336 I consider it highly stable and we are commited to keeping it stable.
338 Of course, in the end, you need to make this call yourself. If you have
339 any questions or concerns, please feel free to email me, or even the list
340 or just stop by #moose and ask away.
342 =head2 Is Moose just Perl 6 in Perl 5?
344 No. While Moose is very much inspired by Perl 6, it is not itself Perl 6.
345 Instead, it is an OO system for Perl 5. I built Moose because I was tired of
346 writing the same old boring Perl 5 OO code, and drooling over Perl 6 OO. So
347 instead of switching to Ruby, I wrote Moose :)
349 =head2 Wait, I<post> modern, I thought it was just I<modern>?
351 So I was reading Larry Wall's talk from the 1999 Linux World entitled
352 "Perl, the first postmodern computer language" in which he talks about how
353 he picked the features for Perl because he thought they were cool and he
354 threw out the ones that he thought sucked. This got me thinking about how
355 we have done the same thing in Moose. For Moose, we have "borrowed" features
356 from Perl 6, CLOS (LISP), Smalltalk, Java, BETA, OCaml, Ruby and more, and
357 the bits we didn't like (cause they sucked) we tossed aside. So for this
358 reason (and a few others) I have re-dubbed Moose a I<postmodern> object system.
362 =head2 Moose Extensions
364 The L<MooseX::> namespace is the official place to find Moose extensions.
365 There are a number of these modules out on CPAN right now the best way to
366 find them is to search for MooseX:: on search.cpan.org.
368 =head1 BUILDING CLASSES WITH MOOSE
370 Moose makes every attempt to provide as much convenience as possible during
371 class construction/definition, but still stay out of your way if you want it
372 to. Here are a few items to note when building classes with Moose.
374 Unless specified with C<extends>, any class which uses Moose will
375 inherit from L<Moose::Object>.
377 Moose will also manage all attributes (including inherited ones) that are
378 defined with C<has>. And (assuming you call C<new>, which is inherited from
379 L<Moose::Object>) this includes properly initializing all instance slots,
380 setting defaults where appropriate, and performing any type constraint checking
383 =head1 EXPORTED FUNCTIONS
385 Moose will export a number of functions into the class's namespace which
386 may then be used to set up the class. These functions all work directly
387 on the current class.
393 This is a method which provides access to the current class's metaclass.
395 =item B<extends (@superclasses)>
397 This function will set the superclass(es) for the current class.
399 This approach is recommended instead of C<use base>, because C<use base>
400 actually C<push>es onto the class's C<@ISA>, whereas C<extends> will
401 replace it. This is important to ensure that classes which do not have
402 superclasses still properly inherit from L<Moose::Object>.
404 =item B<with (@roles)>
406 This will apply a given set of C<@roles> to the local class. Role support
407 is currently under heavy development; see L<Moose::Role> for more details.
409 =item B<has $name =E<gt> %options>
411 This will install an attribute of a given C<$name> into the current class.
412 The C<%options> are the same as those provided by
413 L<Class::MOP::Attribute>, in addition to the list below which are provided
414 by Moose (L<Moose::Meta::Attribute> to be more specific):
418 =item I<is =E<gt> 'rw'|'ro'>
420 The I<is> option accepts either I<rw> (for read/write) or I<ro> (for read
421 only). These will create either a read/write accessor or a read-only
422 accessor respectively, using the same name as the C<$name> of the attribute.
424 If you need more control over how your accessors are named, you can use the
425 I<reader>, I<writer> and I<accessor> options inherited from
426 L<Class::MOP::Attribute>.
428 =item I<isa =E<gt> $type_name>
430 The I<isa> option uses Moose's type constraint facilities to set up runtime
431 type checking for this attribute. Moose will perform the checks during class
432 construction, and within any accessors. The C<$type_name> argument must be a
433 string. The string may be either a class name or a type defined using
434 Moose's type definition features. (Refer to L<Moose::Util::TypeConstraints>
435 for information on how to define a new type, and how to retrieve type meta-data).
437 =item I<coerce =E<gt> (1|0)>
439 This will attempt to use coercion with the supplied type constraint to change
440 the value passed into any accessors or constructors. You B<must> have supplied
441 a type constraint in order for this to work. See L<Moose::Cookbook::Recipe5>
444 =item I<does =E<gt> $role_name>
446 This will accept the name of a role which the value stored in this attribute
447 is expected to have consumed.
449 =item I<required =E<gt> (1|0)>
451 This marks the attribute as being required. This means a I<defined> value must be
452 supplied during class construction, and the attribute may never be set to
453 C<undef> with an accessor.
455 =item I<weak_ref =E<gt> (1|0)>
457 This will tell the class to store the value of this attribute as a weakened
458 reference. If an attribute is a weakened reference, it B<cannot> also be
461 =item I<lazy =E<gt> (1|0)>
463 This will tell the class to not create this slot until absolutely necessary.
464 If an attribute is marked as lazy it B<must> have a default supplied.
466 =item I<auto_deref =E<gt> (1|0)>
468 This tells the accessor whether to automatically dereference the value returned.
469 This is only legal if your C<isa> option is either C<ArrayRef> or C<HashRef>.
471 =item I<metaclass =E<gt> $metaclass_name>
473 This tells the class to use a custom attribute metaclass for this particular
474 attribute. Custom attribute metaclasses are useful for extending the
475 capabilities of the I<has> keyword: they are the simplest way to extend the MOP,
476 but they are still a fairly advanced topic and too much to cover here. I will
477 try and write a recipe on them soon.
479 The default behavior here is to just load C<$metaclass_name>; however, we also
480 have a way to alias to a shorter name. This will first look to see if
481 B<Moose::Meta::Attribute::Custom::$metaclass_name> exists. If it does, Moose
482 will then check to see if that has the method C<register_implementation>, which
483 should return the actual name of the custom attribute metaclass. If there is no
484 C<register_implementation> method, it will fall back to using
485 B<Moose::Meta::Attribute::Custom::$metaclass_name> as the metaclass name.
487 =item I<trigger =E<gt> $code>
489 The I<trigger> option is a CODE reference which will be called after the value of
490 the attribute is set. The CODE ref will be passed the instance itself, the
491 updated value and the attribute meta-object (this is for more advanced fiddling
492 and can typically be ignored). You B<cannot> have a trigger on a read-only
495 =item I<handles =E<gt> ARRAY | HASH | REGEXP | ROLE | CODE>
497 The I<handles> option provides Moose classes with automated delegation features.
498 This is a pretty complex and powerful option. It accepts many different option
499 formats, each with its own benefits and drawbacks.
501 B<NOTE:> This feature is no longer experimental, but it may still have subtle
502 bugs lurking in the deeper corners. If you think you have found a bug, you
503 probably have, so please report it to me right away.
505 B<NOTE:> The class being delegated to does not need to be a Moose based class,
506 which is why this feature is especially useful when wrapping non-Moose classes.
508 All I<handles> option formats share the following traits:
510 You cannot override a locally defined method with a delegated method; an
511 exception will be thrown if you try. That is to say, if you define C<foo> in
512 your class, you cannot override it with a delegated C<foo>. This is almost never
513 something you would want to do, and if it is, you should do it by hand and not
516 You cannot override any of the methods found in Moose::Object, or the C<BUILD>
517 and C<DEMOLISH> methods. These will not throw an exception, but will silently
518 move on to the next method in the list. My reasoning for this is that you would
519 almost never want to do this, since it usually breaks your class. As with
520 overriding locally defined methods, if you do want to do this, you should do it
521 manually, not with Moose.
523 You do not I<need> to have a reader (or accessor) for the attribute in order
524 to delegate to it. Moose will create a means of accessing the value for you,
525 however this will be several times B<less> efficient then if you had given
526 the attribute a reader (or accessor) to use.
528 Below is the documentation for each option format:
534 This is the most common usage for I<handles>. You basically pass a list of
535 method names to be delegated, and Moose will install a delegation method
540 This is the second most common usage for I<handles>. Instead of a list of
541 method names, you pass a HASH ref where each key is the method name you
542 want installed locally, and its value is the name of the original method
543 in the class being delegated to.
545 This can be very useful for recursive classes like trees. Here is a
546 quick example (soon to be expanded into a Moose::Cookbook::Recipe):
551 has 'node' => (is => 'rw', isa => 'Any');
556 default => sub { [] }
564 parent_node => 'node',
565 siblings => 'children',
569 In this example, the Tree package gets C<parent_node> and C<siblings> methods,
570 which delegate to the C<node> and C<children> methods (respectively) of the Tree
571 instance stored in the C<parent> slot.
575 The regexp option works very similar to the ARRAY option, except that it builds
576 the list of methods for you. It starts by collecting all possible methods of the
577 class being delegated to, then filters that list using the regexp supplied here.
579 B<NOTE:> An I<isa> option is required when using the regexp option format. This
580 is so that we can determine (at compile time) the method list from the class.
581 Without an I<isa> this is just not possible.
585 With the role option, you specify the name of a role whose "interface" then
586 becomes the list of methods to handle. The "interface" can be defined as; the
587 methods of the role and any required methods of the role. It should be noted
588 that this does B<not> include any method modifiers or generated attribute
589 methods (which is consistent with role composition).
593 This is the option to use when you really want to do something funky. You should
594 only use it if you really know what you are doing, as it involves manual
597 This takes a code reference, which should expect two arguments. The first is the
598 attribute meta-object this I<handles> is attached to. The second is the
599 metaclass of the class being delegated to. It expects you to return a hash (not
600 a HASH ref) of the methods you want mapped.
606 =item B<has +$name =E<gt> %options>
608 This is variation on the normal attibute creator C<has> which allows you to
609 clone and extend an attribute from a superclass or from a role. Here is an
610 example of the superclass usage:
618 default => 'Hello, I am a Foo'
626 has '+message' => (default => 'Hello I am My::Foo');
628 What is happening here is that B<My::Foo> is cloning the C<message> attribute
629 from its parent class B<Foo>, retaining the C<is =E<gt> 'rw'> and C<isa =E<gt>
630 'Str'> characteristics, but changing the value in C<default>.
632 Here is another example, but within the context of a role:
640 default => 'Hello, I am a Foo'
648 has '+message' => (default => 'Hello I am My::Foo');
650 In this case, we are basically taking the attribute which the role supplied
651 and altering it within the bounds of this feature.
653 Aside from where the attributes come from (one from superclass, the other
654 from a role), this feature works exactly the same. This feature is restricted
655 somewhat, so as to try and force at least I<some> sanity into it. You are only
656 allowed to change the following attributes:
662 Change the default value of an attribute.
666 Change whether the attribute attempts to coerce a value passed to it.
670 Change if the attribute is required to have a value.
672 =item I<documentation>
674 Change the documentation string associated with the attribute.
678 Change if the attribute lazily initializes the slot.
682 You I<are> allowed to change the type, B<if and only if> the new type is a
683 subtype of the old type.
687 You are allowed to B<add> a new C<handles> definition, but you are B<not>
688 allowed to I<change> one.
692 You are allowed to B<add> a new C<builder> definition, but you are B<not>
693 allowed to I<change> one.
697 =item B<before $name|@names =E<gt> sub { ... }>
699 =item B<after $name|@names =E<gt> sub { ... }>
701 =item B<around $name|@names =E<gt> sub { ... }>
703 This three items are syntactic sugar for the before, after, and around method
704 modifier features that L<Class::MOP> provides. More information on these may be
705 found in the L<Class::MOP::Class documentation|Class::MOP::Class/"Method
710 The keyword C<super> is a no-op when called outside of an C<override> method. In
711 the context of an C<override> method, it will call the next most appropriate
712 superclass method with the same arguments as the original method.
714 =item B<override ($name, &sub)>
716 An C<override> method is a way of explicitly saying "I am overriding this
717 method from my superclass". You can call C<super> within this method, and
718 it will work as expected. The same thing I<can> be accomplished with a normal
719 method call and the C<SUPER::> pseudo-package; it is really your choice.
723 The keyword C<inner>, much like C<super>, is a no-op outside of the context of
724 an C<augment> method. You can think of C<inner> as being the inverse of
725 C<super>; the details of how C<inner> and C<augment> work is best described in
726 the L<Moose::Cookbook>.
728 =item B<augment ($name, &sub)>
730 An C<augment> method, is a way of explicitly saying "I am augmenting this
731 method from my superclass". Once again, the details of how C<inner> and
732 C<augment> work is best described in the L<Moose::Cookbook>.
736 This is the C<Carp::confess> function, and exported here because I use it
737 all the time. This feature may change in the future, so you have been warned.
741 This is the C<Scalar::Util::blessed> function, it is exported here because I
742 use it all the time. It is highly recommended that this is used instead of
743 C<ref> anywhere you need to test for an object's class name.
747 =head1 UNIMPORTING FUNCTIONS
751 Moose offers a way to remove the keywords it exports, through the C<unimport>
752 method. You simply have to say C<no Moose> at the bottom of your code for this
753 to work. Here is an example:
758 has 'first_name' => (is => 'rw', isa => 'Str');
759 has 'last_name' => (is => 'rw', isa => 'Str');
763 $self->first_name . ' ' . $self->last_name
766 no Moose; # keywords are removed from the Person package
768 =head1 EXTENDING AND EMBEDDING MOOSE
770 Moose also offers some options for extending or embedding it into your own
771 framework. The basic premise is to have something that sets up your class'
772 metaclass and export the moose declarators (C<has>, C<with>, C<extends>,...).
779 my $CALLER = caller();
784 # we should never export to main
785 return if $CALLER eq 'main';
786 Moose::init_meta( $CALLER, 'MyFramework::Base' );
787 Moose->import({into => $CALLER});
789 # Do my custom framework stuff
796 Moose's C<import> method supports the L<Sub::Exporter> form of C<{into =E<gt> $pkg}>
797 and C<{into_level =E<gt> 1}>
799 =head2 B<init_meta ($class, $baseclass, $metaclass)>
801 Moose does some boot strapping: it creates a metaclass object for your class,
802 and then injects a C<meta> accessor into your class to retrieve it. Then it
803 sets your baseclass to Moose::Object or the value you pass in unless you already
804 have one. This is all done via C<init_meta> which takes the name of your class
805 and optionally a baseclass and a metaclass as arguments.
813 It should be noted that C<super> and C<inner> B<cannot> be used in the same
814 method. However, they may be combined within the same class hierarchy; see
815 F<t/014_override_augment_inner_super.t> for an example.
817 The reason for this is that C<super> is only valid within a method
818 with the C<override> modifier, and C<inner> will never be valid within an
819 C<override> method. In fact, C<augment> will skip over any C<override> methods
820 when searching for its appropriate C<inner>.
822 This might seem like a restriction, but I am of the opinion that keeping these
823 two features separate (yet interoperable) actually makes them easy to use, since
824 their behavior is then easier to predict. Time will tell whether I am right or
825 not (UPDATE: so far so good).
829 =head1 ACKNOWLEDGEMENTS
833 =item I blame Sam Vilain for introducing me to the insanity that is meta-models.
835 =item I blame Audrey Tang for then encouraging my meta-model habit in #perl6.
837 =item Without Yuval "nothingmuch" Kogman this module would not be possible,
838 and it certainly wouldn't have this name ;P
840 =item The basis of the TypeContraints module was Rob Kinyon's idea
841 originally, I just ran with it.
843 =item Thanks to mst & chansen and the whole #moose poose for all the
844 early ideas/feature-requests/encouragement/bug-finding.
846 =item Thanks to David "Theory" Wheeler for meta-discussions and spelling fixes.
854 =item L<http://www.iinteractive.com/moose>
856 This is the official web home of Moose, it contains links to our public SVN repo
857 as well as links to a number of talks and articles on Moose and Moose related
860 =item L<Class::MOP> documentation
862 =item The #moose channel on irc.perl.org
864 =item The Moose mailing list - moose@perl.org
866 =item Moose stats on ohloh.net - L<http://www.ohloh.net/projects/5788>
868 =item Several Moose extension modules in the L<MooseX::> namespace.
876 =item L<http://www.cs.utah.edu/plt/publications/oopsla04-gff.pdf>
878 This paper (suggested by lbr on #moose) was what lead to the implementation
879 of the C<super>/C<override> and C<inner>/C<augment> features. If you really
880 want to understand them, I suggest you read this.
886 All complex software has bugs lurking in it, and this module is no
887 exception. If you find a bug please either email me, or add the bug
892 Stevan Little E<lt>stevan@iinteractive.comE<gt>
894 B<with contributions from:>
900 Anders (Debolaz) Nor Berle
902 Nathan (kolibre) Gray
904 Christian (chansen) Hansen
906 Hans Dieter (confound) Pearcey
908 Eric (ewilhelm) Wilhelm
910 Guillermo (groditi) Roditi
912 Jess (castaway) Robinson
916 Robert (phaylon) Sedlacek
920 Scott (konobi) McWhirter
922 Shlomi (rindolf) Fish
924 Yuval (nothingmuch) Kogman
926 Chris (perigrin) Prather
928 Jonathan (jrockway) Rockway
930 Piotr (dexter) Roszatycki
936 ... and many other #moose folks
938 =head1 COPYRIGHT AND LICENSE
940 Copyright 2006-2008 by Infinity Interactive, Inc.
942 L<http://www.iinteractive.com>
944 This library is free software; you can redistribute it and/or modify
945 it under the same terms as Perl itself.