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 "The make_immutable keyword has been deprecated, " .
172 "please go back to __PACKAGE__->meta->make_immutable\n";
173 $class->meta->make_immutable(@_);
177 return \&Carp::confess;
180 return \&Scalar::Util::blessed;
184 my $exporter = Sub::Exporter::build_exporter(
186 exports => \%exports,
187 groups => { default => [':all'] }
191 # 1 extra level because it's called by import so there's a layer of indirection
195 ref $_[1] && defined $_[1]->{into}
197 : ref $_[1] && defined $_[1]->{into_level}
198 ? caller($offset + $_[1]->{into_level})
203 $CALLER = _get_caller(@_);
205 # this works because both pragmas set $^H (see perldoc perlvar)
206 # which affects the current compilation - i.e. the file who use'd
207 # us - which is why we don't need to do anything special to make
208 # it affect that file rather than this one (which is already compiled)
213 # we should never export to main
214 return if $CALLER eq 'main';
216 init_meta( $CALLER, 'Moose::Object' );
223 my $class = _get_caller(@_);
225 # loop through the exports ...
226 foreach my $name ( keys %exports ) {
229 if ( defined &{ $class . '::' . $name } ) {
230 my $keyword = \&{ $class . '::' . $name };
232 # make sure it is from Moose
233 my ($pkg_name) = Class::MOP::get_code_info($keyword);
235 next if $pkg_name ne 'Moose';
237 # and if it is from Moose then undef the slot
238 delete ${ $class . '::' }{$name};
245 ## make 'em all immutable
247 $_->meta->make_immutable(
248 inline_constructor => 0,
249 inline_accessors => 1, # these are Class::MOP accessors, so they need inlining
252 'Moose::Meta::Attribute',
253 'Moose::Meta::Class',
254 'Moose::Meta::Instance',
256 'Moose::Meta::TypeConstraint',
257 'Moose::Meta::TypeConstraint::Union',
258 'Moose::Meta::TypeConstraint::Parameterized',
259 'Moose::Meta::TypeCoercion',
261 'Moose::Meta::Method',
262 'Moose::Meta::Method::Accessor',
263 'Moose::Meta::Method::Constructor',
264 'Moose::Meta::Method::Destructor',
265 'Moose::Meta::Method::Overriden',
268 'Moose::Meta::Role::Method',
269 'Moose::Meta::Role::Method::Required',
280 Moose - A postmodern object system for Perl 5
285 use Moose; # automatically turns on strict and warnings
287 has 'x' => (is => 'rw', isa => 'Int');
288 has 'y' => (is => 'rw', isa => 'Int');
301 has 'z' => (is => 'rw', isa => 'Int');
303 after 'clear' => sub {
310 Moose is an extension of the Perl 5 object system.
312 =head2 Another object system!?!?
314 Yes, I know there has been an explosion recently of new ways to
315 build object's in Perl 5, most of them based on inside-out objects
316 and other such things. Moose is different because it is not a new
317 object system for Perl 5, but instead an extension of the existing
320 Moose is built on top of L<Class::MOP>, which is a metaclass system
321 for Perl 5. This means that Moose not only makes building normal
322 Perl 5 objects better, but it also provides the power of metaclass
325 =head2 Is this for real? Or is this just an experiment?
327 Moose is I<based> on the prototypes and experiments I did for the Perl 6
328 meta-model. However, Moose is B<NOT> an experiment/prototype; it is for B<real>.
330 =head2 Is this ready for use in production?
332 Yes, I believe that it is.
334 Moose has been used successfully in production environemnts by several people
335 and companies (including the one I work for). There are Moose applications
336 which have been in production with little or no issue now for well over a year.
337 I consider it highly stable and we are commited to keeping it stable.
339 Of course, in the end, you need to make this call yourself. If you have
340 any questions or concerns, please feel free to email me, or even the list
341 or just stop by #moose and ask away.
343 =head2 Is Moose just Perl 6 in Perl 5?
345 No. While Moose is very much inspired by Perl 6, it is not itself Perl 6.
346 Instead, it is an OO system for Perl 5. I built Moose because I was tired of
347 writing the same old boring Perl 5 OO code, and drooling over Perl 6 OO. So
348 instead of switching to Ruby, I wrote Moose :)
350 =head2 Wait, I<post> modern, I thought it was just I<modern>?
352 So I was reading Larry Wall's talk from the 1999 Linux World entitled
353 "Perl, the first postmodern computer language" in which he talks about how
354 he picked the features for Perl because he thought they were cool and he
355 threw out the ones that he thought sucked. This got me thinking about how
356 we have done the same thing in Moose. For Moose, we have "borrowed" features
357 from Perl 6, CLOS (LISP), Smalltalk, Java, BETA, OCaml, Ruby and more, and
358 the bits we didn't like (cause they sucked) we tossed aside. So for this
359 reason (and a few others) I have re-dubbed Moose a I<postmodern> object system.
363 =head2 Moose Extensions
365 The L<MooseX::> namespace is the official place to find Moose extensions.
366 There are a number of these modules out on CPAN right now the best way to
367 find them is to search for MooseX:: on search.cpan.org.
369 =head1 BUILDING CLASSES WITH MOOSE
371 Moose makes every attempt to provide as much convenience as possible during
372 class construction/definition, but still stay out of your way if you want it
373 to. Here are a few items to note when building classes with Moose.
375 Unless specified with C<extends>, any class which uses Moose will
376 inherit from L<Moose::Object>.
378 Moose will also manage all attributes (including inherited ones) that are
379 defined with C<has>. And (assuming you call C<new>, which is inherited from
380 L<Moose::Object>) this includes properly initializing all instance slots,
381 setting defaults where appropriate, and performing any type constraint checking
384 =head1 EXPORTED FUNCTIONS
386 Moose will export a number of functions into the class's namespace which
387 may then be used to set up the class. These functions all work directly
388 on the current class.
394 This is a method which provides access to the current class's metaclass.
396 =item B<extends (@superclasses)>
398 This function will set the superclass(es) for the current class.
400 This approach is recommended instead of C<use base>, because C<use base>
401 actually C<push>es onto the class's C<@ISA>, whereas C<extends> will
402 replace it. This is important to ensure that classes which do not have
403 superclasses still properly inherit from L<Moose::Object>.
405 =item B<with (@roles)>
407 This will apply a given set of C<@roles> to the local class. Role support
408 is currently under heavy development; see L<Moose::Role> for more details.
410 =item B<has $name =E<gt> %options>
412 This will install an attribute of a given C<$name> into the current class.
413 The C<%options> are the same as those provided by
414 L<Class::MOP::Attribute>, in addition to the list below which are provided
415 by Moose (L<Moose::Meta::Attribute> to be more specific):
419 =item I<is =E<gt> 'rw'|'ro'>
421 The I<is> option accepts either I<rw> (for read/write) or I<ro> (for read
422 only). These will create either a read/write accessor or a read-only
423 accessor respectively, using the same name as the C<$name> of the attribute.
425 If you need more control over how your accessors are named, you can use the
426 I<reader>, I<writer> and I<accessor> options inherited from
427 L<Class::MOP::Attribute>.
429 =item I<isa =E<gt> $type_name>
431 The I<isa> option uses Moose's type constraint facilities to set up runtime
432 type checking for this attribute. Moose will perform the checks during class
433 construction, and within any accessors. The C<$type_name> argument must be a
434 string. The string may be either a class name or a type defined using
435 Moose's type definition features. (Refer to L<Moose::Util::TypeConstraints>
436 for information on how to define a new type, and how to retrieve type meta-data).
438 =item I<coerce =E<gt> (1|0)>
440 This will attempt to use coercion with the supplied type constraint to change
441 the value passed into any accessors or constructors. You B<must> have supplied
442 a type constraint in order for this to work. See L<Moose::Cookbook::Recipe5>
445 =item I<does =E<gt> $role_name>
447 This will accept the name of a role which the value stored in this attribute
448 is expected to have consumed.
450 =item I<required =E<gt> (1|0)>
452 This marks the attribute as being required. This means a I<defined> value must be
453 supplied during class construction, and the attribute may never be set to
454 C<undef> with an accessor.
456 =item I<weak_ref =E<gt> (1|0)>
458 This will tell the class to store the value of this attribute as a weakened
459 reference. If an attribute is a weakened reference, it B<cannot> also be
462 =item I<lazy =E<gt> (1|0)>
464 This will tell the class to not create this slot until absolutely necessary.
465 If an attribute is marked as lazy it B<must> have a default supplied.
467 =item I<auto_deref =E<gt> (1|0)>
469 This tells the accessor whether to automatically dereference the value returned.
470 This is only legal if your C<isa> option is either C<ArrayRef> or C<HashRef>.
472 =item I<metaclass =E<gt> $metaclass_name>
474 This tells the class to use a custom attribute metaclass for this particular
475 attribute. Custom attribute metaclasses are useful for extending the
476 capabilities of the I<has> keyword: they are the simplest way to extend the MOP,
477 but they are still a fairly advanced topic and too much to cover here. I will
478 try and write a recipe on them soon.
480 The default behavior here is to just load C<$metaclass_name>; however, we also
481 have a way to alias to a shorter name. This will first look to see if
482 B<Moose::Meta::Attribute::Custom::$metaclass_name> exists. If it does, Moose
483 will then check to see if that has the method C<register_implementation>, which
484 should return the actual name of the custom attribute metaclass. If there is no
485 C<register_implementation> method, it will fall back to using
486 B<Moose::Meta::Attribute::Custom::$metaclass_name> as the metaclass name.
488 =item I<trigger =E<gt> $code>
490 The I<trigger> option is a CODE reference which will be called after the value of
491 the attribute is set. The CODE ref will be passed the instance itself, the
492 updated value and the attribute meta-object (this is for more advanced fiddling
493 and can typically be ignored). You B<cannot> have a trigger on a read-only
496 =item I<handles =E<gt> ARRAY | HASH | REGEXP | ROLE | CODE>
498 The I<handles> option provides Moose classes with automated delegation features.
499 This is a pretty complex and powerful option. It accepts many different option
500 formats, each with its own benefits and drawbacks.
502 B<NOTE:> This feature is no longer experimental, but it may still have subtle
503 bugs lurking in the deeper corners. If you think you have found a bug, you
504 probably have, so please report it to me right away.
506 B<NOTE:> The class being delegated to does not need to be a Moose based class,
507 which is why this feature is especially useful when wrapping non-Moose classes.
509 All I<handles> option formats share the following traits:
511 You cannot override a locally defined method with a delegated method; an
512 exception will be thrown if you try. That is to say, if you define C<foo> in
513 your class, you cannot override it with a delegated C<foo>. This is almost never
514 something you would want to do, and if it is, you should do it by hand and not
517 You cannot override any of the methods found in Moose::Object, or the C<BUILD>
518 and C<DEMOLISH> methods. These will not throw an exception, but will silently
519 move on to the next method in the list. My reasoning for this is that you would
520 almost never want to do this, since it usually breaks your class. As with
521 overriding locally defined methods, if you do want to do this, you should do it
522 manually, not with Moose.
524 You do not I<need> to have a reader (or accessor) for the attribute in order
525 to delegate to it. Moose will create a means of accessing the value for you,
526 however this will be several times B<less> efficient then if you had given
527 the attribute a reader (or accessor) to use.
529 Below is the documentation for each option format:
535 This is the most common usage for I<handles>. You basically pass a list of
536 method names to be delegated, and Moose will install a delegation method
541 This is the second most common usage for I<handles>. Instead of a list of
542 method names, you pass a HASH ref where each key is the method name you
543 want installed locally, and its value is the name of the original method
544 in the class being delegated to.
546 This can be very useful for recursive classes like trees. Here is a
547 quick example (soon to be expanded into a Moose::Cookbook::Recipe):
552 has 'node' => (is => 'rw', isa => 'Any');
557 default => sub { [] }
565 parent_node => 'node',
566 siblings => 'children',
570 In this example, the Tree package gets C<parent_node> and C<siblings> methods,
571 which delegate to the C<node> and C<children> methods (respectively) of the Tree
572 instance stored in the C<parent> slot.
576 The regexp option works very similar to the ARRAY option, except that it builds
577 the list of methods for you. It starts by collecting all possible methods of the
578 class being delegated to, then filters that list using the regexp supplied here.
580 B<NOTE:> An I<isa> option is required when using the regexp option format. This
581 is so that we can determine (at compile time) the method list from the class.
582 Without an I<isa> this is just not possible.
586 With the role option, you specify the name of a role whose "interface" then
587 becomes the list of methods to handle. The "interface" can be defined as; the
588 methods of the role and any required methods of the role. It should be noted
589 that this does B<not> include any method modifiers or generated attribute
590 methods (which is consistent with role composition).
594 This is the option to use when you really want to do something funky. You should
595 only use it if you really know what you are doing, as it involves manual
598 This takes a code reference, which should expect two arguments. The first is the
599 attribute meta-object this I<handles> is attached to. The second is the
600 metaclass of the class being delegated to. It expects you to return a hash (not
601 a HASH ref) of the methods you want mapped.
607 =item B<has +$name =E<gt> %options>
609 This is variation on the normal attibute creator C<has> which allows you to
610 clone and extend an attribute from a superclass or from a role. Here is an
611 example of the superclass usage:
619 default => 'Hello, I am a Foo'
627 has '+message' => (default => 'Hello I am My::Foo');
629 What is happening here is that B<My::Foo> is cloning the C<message> attribute
630 from its parent class B<Foo>, retaining the C<is =E<gt> 'rw'> and C<isa =E<gt>
631 'Str'> characteristics, but changing the value in C<default>.
633 Here is another example, but within the context of a role:
641 default => 'Hello, I am a Foo'
649 has '+message' => (default => 'Hello I am My::Foo');
651 In this case, we are basically taking the attribute which the role supplied
652 and altering it within the bounds of this feature.
654 Aside from where the attributes come from (one from superclass, the other
655 from a role), this feature works exactly the same. This feature is restricted
656 somewhat, so as to try and force at least I<some> sanity into it. You are only
657 allowed to change the following attributes:
663 Change the default value of an attribute.
667 Change whether the attribute attempts to coerce a value passed to it.
671 Change if the attribute is required to have a value.
673 =item I<documentation>
675 Change the documentation string associated with the attribute.
679 Change if the attribute lazily initializes the slot.
683 You I<are> allowed to change the type, B<if and only if> the new type is a
684 subtype of the old type.
688 You are allowed to B<add> a new C<handles> definition, but you are B<not>
689 allowed to I<change> one.
693 You are allowed to B<add> a new C<builder> definition, but you are B<not>
694 allowed to I<change> one.
698 =item B<before $name|@names =E<gt> sub { ... }>
700 =item B<after $name|@names =E<gt> sub { ... }>
702 =item B<around $name|@names =E<gt> sub { ... }>
704 This three items are syntactic sugar for the before, after, and around method
705 modifier features that L<Class::MOP> provides. More information on these may be
706 found in the L<Class::MOP::Class documentation|Class::MOP::Class/"Method
711 The keyword C<super> is a no-op when called outside of an C<override> method. In
712 the context of an C<override> method, it will call the next most appropriate
713 superclass method with the same arguments as the original method.
715 =item B<override ($name, &sub)>
717 An C<override> method is a way of explicitly saying "I am overriding this
718 method from my superclass". You can call C<super> within this method, and
719 it will work as expected. The same thing I<can> be accomplished with a normal
720 method call and the C<SUPER::> pseudo-package; it is really your choice.
724 The keyword C<inner>, much like C<super>, is a no-op outside of the context of
725 an C<augment> method. You can think of C<inner> as being the inverse of
726 C<super>; the details of how C<inner> and C<augment> work is best described in
727 the L<Moose::Cookbook>.
729 =item B<augment ($name, &sub)>
731 An C<augment> method, is a way of explicitly saying "I am augmenting this
732 method from my superclass". Once again, the details of how C<inner> and
733 C<augment> work is best described in the L<Moose::Cookbook>.
737 This is the C<Carp::confess> function, and exported here because I use it
738 all the time. This feature may change in the future, so you have been warned.
742 This is the C<Scalar::Util::blessed> function, it is exported here because I
743 use it all the time. It is highly recommended that this is used instead of
744 C<ref> anywhere you need to test for an object's class name.
748 =head1 UNIMPORTING FUNCTIONS
752 Moose offers a way to remove the keywords it exports, through the C<unimport>
753 method. You simply have to say C<no Moose> at the bottom of your code for this
754 to work. Here is an example:
759 has 'first_name' => (is => 'rw', isa => 'Str');
760 has 'last_name' => (is => 'rw', isa => 'Str');
764 $self->first_name . ' ' . $self->last_name
767 no Moose; # keywords are removed from the Person package
769 =head1 EXTENDING AND EMBEDDING MOOSE
771 Moose also offers some options for extending or embedding it into your own
772 framework. The basic premise is to have something that sets up your class'
773 metaclass and export the moose declarators (C<has>, C<with>, C<extends>,...).
780 my $CALLER = caller();
785 # we should never export to main
786 return if $CALLER eq 'main';
787 Moose::init_meta( $CALLER, 'MyFramework::Base' );
788 Moose->import({into => $CALLER});
790 # Do my custom framework stuff
797 Moose's C<import> method supports the L<Sub::Exporter> form of C<{into =E<gt> $pkg}>
798 and C<{into_level =E<gt> 1}>
800 =head2 B<init_meta ($class, $baseclass, $metaclass)>
802 Moose does some boot strapping: it creates a metaclass object for your class,
803 and then injects a C<meta> accessor into your class to retrieve it. Then it
804 sets your baseclass to Moose::Object or the value you pass in unless you already
805 have one. This is all done via C<init_meta> which takes the name of your class
806 and optionally a baseclass and a metaclass as arguments.
814 It should be noted that C<super> and C<inner> B<cannot> be used in the same
815 method. However, they may be combined within the same class hierarchy; see
816 F<t/014_override_augment_inner_super.t> for an example.
818 The reason for this is that C<super> is only valid within a method
819 with the C<override> modifier, and C<inner> will never be valid within an
820 C<override> method. In fact, C<augment> will skip over any C<override> methods
821 when searching for its appropriate C<inner>.
823 This might seem like a restriction, but I am of the opinion that keeping these
824 two features separate (yet interoperable) actually makes them easy to use, since
825 their behavior is then easier to predict. Time will tell whether I am right or
826 not (UPDATE: so far so good).
830 =head1 ACKNOWLEDGEMENTS
834 =item I blame Sam Vilain for introducing me to the insanity that is meta-models.
836 =item I blame Audrey Tang for then encouraging my meta-model habit in #perl6.
838 =item Without Yuval "nothingmuch" Kogman this module would not be possible,
839 and it certainly wouldn't have this name ;P
841 =item The basis of the TypeContraints module was Rob Kinyon's idea
842 originally, I just ran with it.
844 =item Thanks to mst & chansen and the whole #moose poose for all the
845 early ideas/feature-requests/encouragement/bug-finding.
847 =item Thanks to David "Theory" Wheeler for meta-discussions and spelling fixes.
855 =item L<http://www.iinteractive.com/moose>
857 This is the official web home of Moose, it contains links to our public SVN repo
858 as well as links to a number of talks and articles on Moose and Moose related
861 =item L<Class::MOP> documentation
863 =item The #moose channel on irc.perl.org
865 =item The Moose mailing list - moose@perl.org
867 =item Moose stats on ohloh.net - L<http://www.ohloh.net/projects/5788>
869 =item Several Moose extension modules in the L<MooseX::> namespace.
877 =item L<http://www.cs.utah.edu/plt/publications/oopsla04-gff.pdf>
879 This paper (suggested by lbr on #moose) was what lead to the implementation
880 of the C<super>/C<override> and C<inner>/C<augment> features. If you really
881 want to understand them, I suggest you read this.
887 All complex software has bugs lurking in it, and this module is no
888 exception. If you find a bug please either email me, or add the bug
893 Stevan Little E<lt>stevan@iinteractive.comE<gt>
895 B<with contributions from:>
901 Anders (Debolaz) Nor Berle
903 Nathan (kolibre) Gray
905 Christian (chansen) Hansen
907 Hans Dieter (confound) Pearcey
909 Eric (ewilhelm) Wilhelm
911 Guillermo (groditi) Roditi
913 Jess (castaway) Robinson
917 Robert (phaylon) Sedlacek
921 Scott (konobi) McWhirter
923 Shlomi (rindolf) Fish
925 Yuval (nothingmuch) Kogman
927 Chris (perigrin) Prather
929 Jonathan (jrockway) Rockway
931 Piotr (dexter) Roszatycki
937 ... and many other #moose folks
939 =head1 COPYRIGHT AND LICENSE
941 Copyright 2006-2008 by Infinity Interactive, Inc.
943 L<http://www.iinteractive.com>
945 This library is free software; you can redistribute it and/or modify
946 it under the same terms as Perl itself.