8 our $AUTHORITY = 'cpan:STEVAN';
10 use Scalar::Util 'blessed', 'reftype';
12 use Sub::Name 'subname';
13 use B 'svref_2object';
19 use Moose::Meta::Class;
20 use Moose::Meta::TypeConstraint;
21 use Moose::Meta::TypeCoercion;
22 use Moose::Meta::Attribute;
23 use Moose::Meta::Instance;
26 use Moose::Util::TypeConstraints;
34 # make a subtype for each Moose class
37 => where { $_->isa($class) }
38 => optimize_as { blessed($_[0]) && $_[0]->isa($class) }
39 unless find_type_constraint($class);
42 if ($class->can('meta')) {
44 # this is the case where the metaclass pragma
45 # was used before the 'use Moose' statement to
46 # override a specific class
47 $meta = $class->meta();
48 (blessed($meta) && $meta->isa('Moose::Meta::Class'))
49 || confess "You already have a &meta function, but it does not return a Moose::Meta::Class";
53 # this is broken currently, we actually need
54 # to allow the possiblity of an inherited
55 # meta, which will not be visible until the
56 # user 'extends' first. This needs to have
57 # more intelligence to it
58 $meta = Moose::Meta::Class->initialize($class);
59 $meta->add_method('meta' => sub {
60 # re-initialize so it inherits properly
61 Moose::Meta::Class->initialize(blessed($_[0]) || $_[0]);
65 # make sure they inherit from Moose::Object
66 $meta->superclasses('Moose::Object')
67 unless $meta->superclasses();
73 return subname 'Moose::extends' => sub (@) {
74 confess "Must derive at least one class" unless @_;
75 Class::MOP::load_class($_) for @_;
76 # this checks the metaclass to make sure
77 # it is correct, sometimes it can get out
78 # of sync when the classes are being built
79 my $meta = $class->meta->_fix_metaclass_incompatability(@_);
80 $meta->superclasses(@_);
85 return subname 'Moose::with' => sub (@) {
87 confess "Must specify at least one role" unless @roles;
88 Class::MOP::load_class($_) for @roles;
89 $class->meta->_apply_all_roles(@roles);
94 return subname 'Moose::has' => sub ($;%) {
95 my ($name, %options) = @_;
96 my $attrs = (ref($name) eq 'ARRAY') ? $name : [($name)];
97 $class->meta->_process_attribute($_, %options) for @$attrs;
102 return subname 'Moose::before' => sub (@&) {
104 my $meta = $class->meta;
105 $meta->add_before_method_modifier($_, $code) for @_;
110 return subname 'Moose::after' => sub (@&) {
112 my $meta = $class->meta;
113 $meta->add_after_method_modifier($_, $code) for @_;
118 return subname 'Moose::around' => sub (@&) {
120 my $meta = $class->meta;
121 $meta->add_around_method_modifier($_, $code) for @_;
125 return subname 'Moose::super' => sub {};
129 return subname 'Moose::override' => sub ($&) {
130 my ($name, $method) = @_;
131 $class->meta->add_override_method_modifier($name => $method);
135 return subname 'Moose::inner' => sub {};
139 return subname 'Moose::augment' => sub (@&) {
140 my ($name, $method) = @_;
141 $class->meta->add_augment_method_modifier($name => $method);
146 # this is experimental, but I am not
147 # happy with it. If you want to try
148 # it, you will have to uncomment it
150 # There is a really good chance that
151 # this will be deprecated, dont get
154 # return subname 'Moose::self' => sub {};
157 # my $class = $CALLER;
158 # return subname 'Moose::method' => sub {
159 # my ($name, $method) = @_;
160 # $class->meta->add_method($name, sub {
163 # no warnings 'redefine';
164 # local *{$class->meta->name . '::self'} = sub { $self };
171 return \&Carp::confess;
174 return \&Scalar::Util::blessed;
178 my $exporter = Sub::Exporter::build_exporter({
179 exports => \%exports,
191 # we should never export to main
192 return if $CALLER eq 'main';
201 my $class = caller();
202 # loop through the exports ...
203 foreach my $name (keys %exports) {
204 next if $name =~ /inner|super|self/;
207 if (defined &{$class . '::' . $name}) {
208 my $keyword = \&{$class . '::' . $name};
210 # make sure it is from Moose
211 my $pkg_name = eval { svref_2object($keyword)->GV->STASH->NAME };
213 next if $pkg_name ne 'Moose';
215 # and if it is from Moose then undef the slot
216 delete ${$class . '::'}{$name};
224 ## make 'em all immutable
226 $_->meta->make_immutable(
227 inline_constructor => 0,
228 inline_accessors => 0,
230 'Moose::Meta::Attribute',
231 'Moose::Meta::Class',
232 'Moose::Meta::Instance',
234 'Moose::Meta::TypeConstraint',
235 'Moose::Meta::TypeConstraint::Union',
236 'Moose::Meta::TypeCoercion',
238 'Moose::Meta::Method',
239 'Moose::Meta::Method::Accessor',
240 'Moose::Meta::Method::Constructor',
241 'Moose::Meta::Method::Overriden',
252 Moose - A complete modern object system for Perl 5
261 has 'x' => (is => 'rw', isa => 'Int');
262 has 'y' => (is => 'rw', isa => 'Int');
277 has 'z' => (is => 'rw', isa => 'Int');
279 after 'clear' => sub {
286 Moose is an extension of the Perl 5 object system.
288 =head2 Another object system!?!?
290 Yes, I know there has been an explosion recently of new ways to
291 build object's in Perl 5, most of them based on inside-out objects
292 and other such things. Moose is different because it is not a new
293 object system for Perl 5, but instead an extension of the existing
296 Moose is built on top of L<Class::MOP>, which is a metaclass system
297 for Perl 5. This means that Moose not only makes building normal
298 Perl 5 objects better, but it also provides the power of metaclass
301 =head2 Is this for real? Or is this just an experiment?
303 Moose is I<based> on the prototypes and experiments I did for the Perl 6
304 meta-model; however Moose is B<NOT> an experiment/prototype, it is
307 =head2 Is this ready for use in production?
309 Yes, I believe that it is.
311 I have two medium-to-large-ish web applications which use Moose heavily
312 and have been in production (without issue) for several months now. At
313 $work, we are re-writing our core offering in it. And several people on
314 #moose have been using it (in production) for several months now as well.
316 Of course, in the end, you need to make this call yourself. If you have
317 any questions or concerns, please feel free to email me, or even the list
318 or just stop by #moose and ask away.
320 =head2 Is Moose just Perl 6 in Perl 5?
322 No. While Moose is very much inspired by Perl 6, it is not itself Perl 6.
323 Instead, it is an OO system for Perl 5. I built Moose because I was tired or
324 writing the same old boring Perl 5 OO code, and drooling over Perl 6 OO. So
325 instead of switching to Ruby, I wrote Moose :)
327 =head1 BUILDING CLASSES WITH MOOSE
329 Moose makes every attempt to provide as much convenience as possible during
330 class construction/definition, but still stay out of your way if you want it
331 to. Here are a few items to note when building classes with Moose.
333 Unless specified with C<extends>, any class which uses Moose will
334 inherit from L<Moose::Object>.
336 Moose will also manage all attributes (including inherited ones) that
337 are defined with C<has>. And assuming that you call C<new>, which is
338 inherited from L<Moose::Object>, then this includes properly initializing
339 all instance slots, setting defaults where appropriate, and performing any
340 type constraint checking or coercion.
342 =head1 EXPORTED FUNCTIONS
344 Moose will export a number of functions into the class's namespace which
345 can then be used to set up the class. These functions all work directly
346 on the current class.
352 This is a method which provides access to the current class's metaclass.
354 =item B<extends (@superclasses)>
356 This function will set the superclass(es) for the current class.
358 This approach is recommended instead of C<use base>, because C<use base>
359 actually C<push>es onto the class's C<@ISA>, whereas C<extends> will
360 replace it. This is important to ensure that classes which do not have
361 superclasses still properly inherit from L<Moose::Object>.
363 =item B<with (@roles)>
365 This will apply a given set of C<@roles> to the local class. Role support
366 is currently under heavy development; see L<Moose::Role> for more details.
368 =item B<has $name =E<gt> %options>
370 This will install an attribute of a given C<$name> into the current class.
371 The list of C<%options> are the same as those provided by
372 L<Class::MOP::Attribute>, in addition to the list below which are provided
373 by Moose (L<Moose::Meta::Attribute> to be more specific):
377 =item I<is =E<gt> 'rw'|'ro'>
379 The I<is> option accepts either I<rw> (for read/write) or I<ro> (for read
380 only). These will create either a read/write accessor or a read-only
381 accessor respectively, using the same name as the C<$name> of the attribute.
383 If you need more control over how your accessors are named, you can use the
384 I<reader>, I<writer> and I<accessor> options inherited from L<Class::MOP::Attribute>.
386 =item I<isa =E<gt> $type_name>
388 The I<isa> option uses Moose's type constraint facilities to set up runtime
389 type checking for this attribute. Moose will perform the checks during class
390 construction, and within any accessors. The C<$type_name> argument must be a
391 string. The string can be either a class name or a type defined using
392 Moose's type definition features.
394 =item I<coerce =E<gt> (1|0)>
396 This will attempt to use coercion with the supplied type constraint to change
397 the value passed into any accessors or constructors. You B<must> have supplied
398 a type constraint in order for this to work. See L<Moose::Cookbook::Recipe5>
399 for an example usage.
401 =item I<does =E<gt> $role_name>
403 This will accept the name of a role which the value stored in this attribute
404 is expected to have consumed.
406 =item I<required =E<gt> (1|0)>
408 This marks the attribute as being required. This means a value must be supplied
409 during class construction, and the attribute can never be set to C<undef> with
412 =item I<weak_ref =E<gt> (1|0)>
414 This will tell the class to store the value of this attribute as a weakened
415 reference. If an attribute is a weakened reference, it B<cannot> also be
418 =item I<lazy =E<gt> (1|0)>
420 This will tell the class to not create this slot until absolutely necessary.
421 If an attribute is marked as lazy it B<must> have a default supplied.
423 =item I<auto_deref =E<gt> (1|0)>
425 This tells the accessor whether to automatically dereference the value returned.
426 This is only legal if your C<isa> option is either an C<ArrayRef> or C<HashRef>.
428 =item I<metaclass =E<gt> $metaclass_name>
430 This tells the class to use a custom attribute metaclass for this particular
431 attribute. Custom attribute metaclasses are useful for extending the capabilities
432 of the I<has> keyword, they are the simplest way to extend the MOP, but they are
433 still a fairly advanced topic and too much to cover here. I will try and write a
436 The default behavior here is to just load C<$metaclass_name>, however, we also
437 have a way to alias to a shorter name. This will first look to see if
438 B<Moose::Meta::Attribute::Custom::$metaclass_name> exists, if it does it will
439 then check to see if that has the method C<register_implemenetation> which
440 should return the actual name of the custom attribute metaclass. If there is
441 no C<register_implemenetation> method, it will just default to using
442 B<Moose::Meta::Attribute::Custom::$metaclass_name> as the metaclass name.
444 =item I<trigger =E<gt> $code>
446 The trigger option is a CODE reference which will be called after the value of
447 the attribute is set. The CODE ref will be passed the instance itself, the
448 updated value and the attribute meta-object (this is for more advanced fiddling
449 and can typically be ignored in most cases). You B<cannot> have a trigger on
450 a read-only attribute.
452 =item I<handles =E<gt> ARRAY | HASH | REGEXP | CODE>
454 The handles option provides Moose classes with automated delegation features.
455 This is a pretty complex and powerful option, it accepts many different option
456 formats, each with it's own benefits and drawbacks.
458 B<NOTE:> This features is no longer experimental, but it still may have subtle
459 bugs lurking in the deeper corners. So if you think you have found a bug, you
460 probably have, so please report it to me right away.
462 B<NOTE:> The class being delegated to does not need to be a Moose based class.
463 Which is why this feature is especially useful when wrapping non-Moose classes.
465 All handles option formats share the following traits.
467 You cannot override a locally defined method with a delegated method, an
468 exception will be thrown if you try. Meaning, if you define C<foo> in your
469 class, you cannot override it with a delegated C<foo>. This is almost never
470 something you would want to do, and if it is, you should do it by hand and
473 You cannot override any of the methods found in Moose::Object as well as
474 C<BUILD> or C<DEMOLISH> methods. These will not throw an exception, but will
475 silently move on to the next method in the list. My reasoning for this is that
476 you would almost never want to do this because it usually tends to break your
477 class. And as with overriding locally defined methods, if you do want to do this,
478 you should do it manually and not with Moose.
480 Below is the documentation for each option format:
486 This is the most common usage for handles. You basically pass a list of
487 method names to be delegated, and Moose will install a delegation method
488 for each one in the list.
492 This is the second most common usage for handles. Instead of a list of
493 method names, you pass a HASH ref where the key is the method name you
494 want installed locally, and the value is the name of the original method
495 in the class being delegated to.
497 This can be very useful for recursive classes like trees, here is a
498 quick example (soon to be expanded into a Moose::Cookbook::Recipe):
503 has 'node' => (is => 'rw', isa => 'Any');
508 default => sub { [] }
516 parent_node => 'node',
517 siblings => 'children',
521 In this example, the Tree package gets the C<parent_node> and C<siblings> methods
522 which delegate to the C<node> and C<children> methods of the Tree instance stored
527 The regexp option works very similar to the ARRAY option, except that it builds
528 the list of methods for you. It starts by collecting all possible methods of the
529 class being delegated to, then filters that list using the regexp supplied here.
531 B<NOTE:> An I<isa> option is required when using the regexp option format. This
532 is so that we can determine (at compile time) the method list from the class.
533 Without an I<isa> this is just not possible.
537 This is the option to use when you really want to do something funky. You should
538 only use it if you really know what you are doing as it involves manual metaclass
541 This takes a code reference, which should expect two arguments. The first is
542 the attribute meta-object this I<handles> is attached to. The second is the metaclass
543 of the class being delegated to. It expects you to return a hash (not a HASH ref)
544 of the methods you want mapped.
550 =item B<has +$name =E<gt> %options>
552 This is variation on the normal attibute creator C<has>, which allows you to
553 clone and extend an attribute from a superclass. Here is a quick example:
561 default => 'Hello, I am a Foo'
569 has '+message' => (default => 'Hello I am My::Foo');
571 What is happening here is that B<My::Foo> is cloning the C<message> attribute
572 from it's parent class B<Foo>, retaining the is =E<gt> 'rw' and isa =E<gt> 'Str'
573 characteristics, but changing the value in C<default>.
575 This feature is restricted somewhat, so as to try and enfore at least I<some>
576 sanity into it. You are only allowed to change the following attributes:
582 Change the default value of an attribute.
586 Change whether the attribute attempts to coerce a value passed to it.
590 Change if the attribute is required to have a value.
592 =item I<documentation>
594 Change the documentation string associated with the attribute.
598 You I<are> allowed to change the type, but if and B<only if> the new type is
599 a subtype of the old type.
603 =item B<before $name|@names =E<gt> sub { ... }>
605 =item B<after $name|@names =E<gt> sub { ... }>
607 =item B<around $name|@names =E<gt> sub { ... }>
609 This three items are syntactic sugar for the before, after, and around method
610 modifier features that L<Class::MOP> provides. More information on these can
611 be found in the L<Class::MOP> documentation for now.
615 The keyword C<super> is a no-op when called outside of an C<override> method. In
616 the context of an C<override> method, it will call the next most appropriate
617 superclass method with the same arguments as the original method.
619 =item B<override ($name, &sub)>
621 An C<override> method is a way of explicitly saying "I am overriding this
622 method from my superclass". You can call C<super> within this method, and
623 it will work as expected. The same thing I<can> be accomplished with a normal
624 method call and the C<SUPER::> pseudo-package; it is really your choice.
628 The keyword C<inner>, much like C<super>, is a no-op outside of the context of
629 an C<augment> method. You can think of C<inner> as being the inverse of
630 C<super>; the details of how C<inner> and C<augment> work is best described in
631 the L<Moose::Cookbook>.
633 =item B<augment ($name, &sub)>
635 An C<augment> method, is a way of explicitly saying "I am augmenting this
636 method from my superclass". Once again, the details of how C<inner> and
637 C<augment> work is best described in the L<Moose::Cookbook>.
641 This is the C<Carp::confess> function, and exported here because I use it
642 all the time. This feature may change in the future, so you have been warned.
646 This is the C<Scalar::Uti::blessed> function, it is exported here because I
647 use it all the time. It is highly recommended that this is used instead of
648 C<ref> anywhere you need to test for an object's class name.
652 =head1 UNEXPORTING FUNCTIONS
656 Moose offers a way of removing the keywords it exports though the C<unimport>
657 method. You simply have to say C<no Moose> at the bottom of your code for this
658 to work. Here is an example:
663 has 'first_name' => (is => 'rw', isa => 'Str');
664 has 'last_name' => (is => 'rw', isa => 'Str');
668 $self->first_name . ' ' . $self->last_name
671 no Moose; # keywords are removed from the Person package
675 =head2 What does Moose stand for??
677 Moose doesn't stand for one thing in particular, however, if you
678 want, here are a few of my favorites; feel free to contribute
683 =item Make Other Object Systems Envious
685 =item Makes Object Orientation So Easy
687 =item Makes Object Orientation Spiffy- Er (sorry ingy)
689 =item Most Other Object Systems Emasculate
691 =item Moose Often Ovulate Sorta Early
693 =item Moose Offers Often Super Extensions
695 =item Meta Object Orientation Syntax Extensions
705 It should be noted that C<super> and C<inner> C<cannot> be used in the same
706 method. However, they can be combined together with the same class hierarchy;
707 see F<t/014_override_augment_inner_super.t> for an example.
709 The reason for this is that C<super> is only valid within a method
710 with the C<override> modifier, and C<inner> will never be valid within an
711 C<override> method. In fact, C<augment> will skip over any C<override> methods
712 when searching for its appropriate C<inner>.
714 This might seem like a restriction, but I am of the opinion that keeping these
715 two features separate (but interoperable) actually makes them easy to use, since
716 their behavior is then easier to predict. Time will tell if I am right or not.
720 =head1 ACKNOWLEDGEMENTS
724 =item I blame Sam Vilain for introducing me to the insanity that is meta-models.
726 =item I blame Audrey Tang for then encouraging my meta-model habit in #perl6.
728 =item Without Yuval "nothingmuch" Kogman this module would not be possible,
729 and it certainly wouldn't have this name ;P
731 =item The basis of the TypeContraints module was Rob Kinyon's idea
732 originally, I just ran with it.
734 =item Thanks to mst & chansen and the whole #moose poose for all the
735 ideas/feature-requests/encouragement/bug-finding.
737 =item Thanks to David "Theory" Wheeler for meta-discussions and spelling fixes.
745 =item L<Class::MOP> documentation
747 =item The #moose channel on irc.perl.org
749 =item The Moose mailing list - moose@perl.org
751 =item L<http://forum2.org/moose/>
753 =item L<http://www.cs.utah.edu/plt/publications/oopsla04-gff.pdf>
755 This paper (suggested by lbr on #moose) was what lead to the implementation
756 of the C<super>/C<overrride> and C<inner>/C<augment> features. If you really
757 want to understand this feature, I suggest you read this.
763 All complex software has bugs lurking in it, and this module is no
764 exception. If you find a bug please either email me, or add the bug
769 Stevan Little E<lt>stevan@iinteractive.comE<gt>
771 Christian Hansen E<lt>chansen@cpan.orgE<gt>
773 Yuval Kogman E<lt>nothingmuch@woobling.orgE<gt>
775 =head1 COPYRIGHT AND LICENSE
777 Copyright 2006, 2007 by Infinity Interactive, Inc.
779 L<http://www.iinteractive.com>
781 This library is free software; you can redistribute it and/or modify
782 it under the same terms as Perl itself.