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 @_;
128 $SUPER_SLOT{$CALLER} = \*{"${CALLER}::super"};
130 return subname 'Moose::super' => sub {};
134 return subname 'Moose::override' => sub ($&) {
135 my ($name, $method) = @_;
136 $class->meta->add_override_method_modifier($name => $method);
143 $INNER_SLOT{$CALLER} = \*{"${CALLER}::inner"};
145 return subname 'Moose::inner' => sub {};
149 return subname 'Moose::augment' => sub (@&) {
150 my ($name, $method) = @_;
151 $class->meta->add_augment_method_modifier($name => $method);
156 # this is experimental, but I am not
157 # happy with it. If you want to try
158 # it, you will have to uncomment it
160 # There is a really good chance that
161 # this will be deprecated, dont get
164 # return subname 'Moose::self' => sub {};
167 # my $class = $CALLER;
168 # return subname 'Moose::method' => sub {
169 # my ($name, $method) = @_;
170 # $class->meta->add_method($name, sub {
173 # no warnings 'redefine';
174 # local *{$class->meta->name . '::self'} = sub { $self };
181 return \&Carp::confess;
184 return \&Scalar::Util::blessed;
188 my $exporter = Sub::Exporter::build_exporter({
189 exports => \%exports,
201 # we should never export to main
202 return if $CALLER eq 'main';
211 my $class = caller();
212 # loop through the exports ...
213 foreach my $name (keys %exports) {
216 if (defined &{$class . '::' . $name}) {
217 my $keyword = \&{$class . '::' . $name};
219 # make sure it is from Moose
220 my $pkg_name = eval { svref_2object($keyword)->GV->STASH->NAME };
222 next if $pkg_name ne 'Moose';
224 # and if it is from Moose then undef the slot
225 delete ${$class . '::'}{$name};
233 ## make 'em all immutable
235 $_->meta->make_immutable(
236 inline_constructor => 0,
237 inline_accessors => 0,
239 'Moose::Meta::Attribute',
240 'Moose::Meta::Class',
241 'Moose::Meta::Instance',
243 'Moose::Meta::TypeConstraint',
244 'Moose::Meta::TypeConstraint::Union',
245 'Moose::Meta::TypeCoercion',
247 'Moose::Meta::Method',
248 'Moose::Meta::Method::Accessor',
249 'Moose::Meta::Method::Constructor',
250 'Moose::Meta::Method::Overriden',
261 Moose - A complete modern object system for Perl 5
266 use Moose; # automatically turns on strict and warnings
268 has 'x' => (is => 'rw', isa => 'Int');
269 has 'y' => (is => 'rw', isa => 'Int');
282 has 'z' => (is => 'rw', isa => 'Int');
284 after 'clear' => sub {
291 Moose is an extension of the Perl 5 object system.
293 =head2 Another object system!?!?
295 Yes, I know there has been an explosion recently of new ways to
296 build object's in Perl 5, most of them based on inside-out objects
297 and other such things. Moose is different because it is not a new
298 object system for Perl 5, but instead an extension of the existing
301 Moose is built on top of L<Class::MOP>, which is a metaclass system
302 for Perl 5. This means that Moose not only makes building normal
303 Perl 5 objects better, but it also provides the power of metaclass
306 =head2 Is this for real? Or is this just an experiment?
308 Moose is I<based> on the prototypes and experiments I did for the Perl 6
309 meta-model. However, Moose is B<NOT> an experiment/prototype; it is for B<real>.
311 =head2 Is this ready for use in production?
313 Yes, I believe that it is.
315 I have two medium-to-large-ish web applications which use Moose heavily
316 and have been in production (without issue) for several months now. At
317 $work, we are re-writing our core offering in it. And several people on
318 #moose have been using it (in production) for several months now as well.
320 Of course, in the end, you need to make this call yourself. If you have
321 any questions or concerns, please feel free to email me, or even the list
322 or just stop by #moose and ask away.
324 =head2 Is Moose just Perl 6 in Perl 5?
326 No. While Moose is very much inspired by Perl 6, it is not itself Perl 6.
327 Instead, it is an OO system for Perl 5. I built Moose because I was tired of
328 writing the same old boring Perl 5 OO code, and drooling over Perl 6 OO. So
329 instead of switching to Ruby, I wrote Moose :)
331 =head1 BUILDING CLASSES WITH MOOSE
333 Moose makes every attempt to provide as much convenience as possible during
334 class construction/definition, but still stay out of your way if you want it
335 to. Here are a few items to note when building classes with Moose.
337 Unless specified with C<extends>, any class which uses Moose will
338 inherit from L<Moose::Object>.
340 Moose will also manage all attributes (including inherited ones) that are
341 defined with C<has>. And (assuming you call C<new>, which is inherited from
342 L<Moose::Object>) this includes properly initializing all instance slots,
343 setting defaults where appropriate, and performing any type constraint checking
346 =head1 EXPORTED FUNCTIONS
348 Moose will export a number of functions into the class's namespace which
349 may then be used to set up the class. These functions all work directly
350 on the current class.
356 This is a method which provides access to the current class's metaclass.
358 =item B<extends (@superclasses)>
360 This function will set the superclass(es) for the current class.
362 This approach is recommended instead of C<use base>, because C<use base>
363 actually C<push>es onto the class's C<@ISA>, whereas C<extends> will
364 replace it. This is important to ensure that classes which do not have
365 superclasses still properly inherit from L<Moose::Object>.
367 =item B<with (@roles)>
369 This will apply a given set of C<@roles> to the local class. Role support
370 is currently under heavy development; see L<Moose::Role> for more details.
372 =item B<has $name =E<gt> %options>
374 This will install an attribute of a given C<$name> into the current class.
375 The C<%options> are the same as those provided by
376 L<Class::MOP::Attribute>, in addition to the list below which are provided
377 by Moose (L<Moose::Meta::Attribute> to be more specific):
381 =item I<is =E<gt> 'rw'|'ro'>
383 The I<is> option accepts either I<rw> (for read/write) or I<ro> (for read
384 only). These will create either a read/write accessor or a read-only
385 accessor respectively, using the same name as the C<$name> of the attribute.
387 If you need more control over how your accessors are named, you can use the
388 I<reader>, I<writer> and I<accessor> options inherited from
389 L<Class::MOP::Attribute>.
391 =item I<isa =E<gt> $type_name>
393 The I<isa> option uses Moose's type constraint facilities to set up runtime
394 type checking for this attribute. Moose will perform the checks during class
395 construction, and within any accessors. The C<$type_name> argument must be a
396 string. The string may be either a class name or a type defined using
397 Moose's type definition features.
399 =item I<coerce =E<gt> (1|0)>
401 This will attempt to use coercion with the supplied type constraint to change
402 the value passed into any accessors or constructors. You B<must> have supplied
403 a type constraint in order for this to work. See L<Moose::Cookbook::Recipe5>
406 =item I<does =E<gt> $role_name>
408 This will accept the name of a role which the value stored in this attribute
409 is expected to have consumed.
411 =item I<required =E<gt> (1|0)>
413 This marks the attribute as being required. This means a value must be supplied
414 during class construction, and the attribute may never be set to C<undef> with
417 =item I<weak_ref =E<gt> (1|0)>
419 This will tell the class to store the value of this attribute as a weakened
420 reference. If an attribute is a weakened reference, it B<cannot> also be
423 =item I<lazy =E<gt> (1|0)>
425 This will tell the class to not create this slot until absolutely necessary.
426 If an attribute is marked as lazy it B<must> have a default supplied.
428 =item I<auto_deref =E<gt> (1|0)>
430 This tells the accessor whether to automatically dereference the value returned.
431 This is only legal if your C<isa> option is either C<ArrayRef> or C<HashRef>.
433 =item I<metaclass =E<gt> $metaclass_name>
435 This tells the class to use a custom attribute metaclass for this particular
436 attribute. Custom attribute metaclasses are useful for extending the
437 capabilities of the I<has> keyword: they are the simplest way to extend the MOP,
438 but they are still a fairly advanced topic and too much to cover here. I will
439 try and write a recipe on them soon.
441 The default behavior here is to just load C<$metaclass_name>; however, we also
442 have a way to alias to a shorter name. This will first look to see if
443 B<Moose::Meta::Attribute::Custom::$metaclass_name> exists. If it does, Moose
444 will then check to see if that has the method C<register_implemenetation>, which
445 should return the actual name of the custom attribute metaclass. If there is no
446 C<register_implemenetation> method, it will fall back to using
447 B<Moose::Meta::Attribute::Custom::$metaclass_name> as the metaclass name.
449 =item I<trigger =E<gt> $code>
451 The I<trigger> option is a CODE reference which will be called after the value of
452 the attribute is set. The CODE ref will be passed the instance itself, the
453 updated value and the attribute meta-object (this is for more advanced fiddling
454 and can typically be ignored). You B<cannot> have a trigger on a read-only
457 =item I<handles =E<gt> ARRAY | HASH | REGEXP | CODE>
459 The I<handles> option provides Moose classes with automated delegation features.
460 This is a pretty complex and powerful option. It accepts many different option
461 formats, each with its own benefits and drawbacks.
463 B<NOTE:> This feature is no longer experimental, but it may still have subtle
464 bugs lurking in the deeper corners. If you think you have found a bug, you
465 probably have, so please report it to me right away.
467 B<NOTE:> The class being delegated to does not need to be a Moose based class,
468 which is why this feature is especially useful when wrapping non-Moose classes.
470 All I<handles> option formats share the following traits:
472 You cannot override a locally defined method with a delegated method; an
473 exception will be thrown if you try. That is to say, if you define C<foo> in
474 your class, you cannot override it with a delegated C<foo>. This is almost never
475 something you would want to do, and if it is, you should do it by hand and not
478 You cannot override any of the methods found in Moose::Object, or the C<BUILD>
479 and C<DEMOLISH> methods. These will not throw an exception, but will silently
480 move on to the next method in the list. My reasoning for this is that you would
481 almost never want to do this, since it usually breaks your class. As with
482 overriding locally defined methods, if you do want to do this, you should do it
483 manually, not with Moose.
485 Below is the documentation for each option format:
491 This is the most common usage for I<handles>. You basically pass a list of
492 method names to be delegated, and Moose will install a delegation method
497 This is the second most common usage for I<handles>. Instead of a list of
498 method names, you pass a HASH ref where each key is the method name you
499 want installed locally, and its value is the name of the original method
500 in the class being delegated to.
502 This can be very useful for recursive classes like trees. Here is a
503 quick example (soon to be expanded into a Moose::Cookbook::Recipe):
508 has 'node' => (is => 'rw', isa => 'Any');
513 default => sub { [] }
521 parent_node => 'node',
522 siblings => 'children',
526 In this example, the Tree package gets C<parent_node> and C<siblings> methods,
527 which delegate to the C<node> and C<children> methods (respectively) of the Tree
528 instance stored in the C<parent> slot.
532 The regexp option works very similar to the ARRAY option, except that it builds
533 the list of methods for you. It starts by collecting all possible methods of the
534 class being delegated to, then filters that list using the regexp supplied here.
536 B<NOTE:> An I<isa> option is required when using the regexp option format. This
537 is so that we can determine (at compile time) the method list from the class.
538 Without an I<isa> this is just not possible.
542 This is the option to use when you really want to do something funky. You should
543 only use it if you really know what you are doing, as it involves manual
546 This takes a code reference, which should expect two arguments. The first is the
547 attribute meta-object this I<handles> is attached to. The second is the
548 metaclass of the class being delegated to. It expects you to return a hash (not
549 a HASH ref) of the methods you want mapped.
555 =item B<has +$name =E<gt> %options>
557 This is variation on the normal attibute creator C<has> which allows you to
558 clone and extend an attribute from a superclass. Here is a quick example:
566 default => 'Hello, I am a Foo'
574 has '+message' => (default => 'Hello I am My::Foo');
576 What is happening here is that B<My::Foo> is cloning the C<message> attribute
577 from its parent class B<Foo>, retaining the C<is =E<gt> 'rw'> and C<isa =E<gt>
578 'Str'> characteristics, but changing the value in C<default>.
580 This feature is restricted somewhat, so as to try and enfore at least I<some>
581 sanity into it. You are only allowed to change the following attributes:
587 Change the default value of an attribute.
591 Change whether the attribute attempts to coerce a value passed to it.
595 Change if the attribute is required to have a value.
597 =item I<documentation>
599 Change the documentation string associated with the attribute.
603 You I<are> allowed to change the type, B<if and only if> the new type is a
604 subtype of the old type.
608 =item B<before $name|@names =E<gt> sub { ... }>
610 =item B<after $name|@names =E<gt> sub { ... }>
612 =item B<around $name|@names =E<gt> sub { ... }>
614 This three items are syntactic sugar for the before, after, and around method
615 modifier features that L<Class::MOP> provides. More information on these may
616 be found in the L<Class::MOP> documentation for now.
620 The keyword C<super> is a no-op when called outside of an C<override> method. In
621 the context of an C<override> method, it will call the next most appropriate
622 superclass method with the same arguments as the original method.
624 =item B<override ($name, &sub)>
626 An C<override> method is a way of explicitly saying "I am overriding this
627 method from my superclass". You can call C<super> within this method, and
628 it will work as expected. The same thing I<can> be accomplished with a normal
629 method call and the C<SUPER::> pseudo-package; it is really your choice.
633 The keyword C<inner>, much like C<super>, is a no-op outside of the context of
634 an C<augment> method. You can think of C<inner> as being the inverse of
635 C<super>; the details of how C<inner> and C<augment> work is best described in
636 the L<Moose::Cookbook>.
638 =item B<augment ($name, &sub)>
640 An C<augment> method, is a way of explicitly saying "I am augmenting this
641 method from my superclass". Once again, the details of how C<inner> and
642 C<augment> work is best described in the L<Moose::Cookbook>.
646 This is the C<Carp::confess> function, and exported here because I use it
647 all the time. This feature may change in the future, so you have been warned.
651 This is the C<Scalar::Util::blessed> function, it is exported here because I
652 use it all the time. It is highly recommended that this is used instead of
653 C<ref> anywhere you need to test for an object's class name.
657 =head1 UNIMPORTING FUNCTIONS
661 Moose offers a way to remove the keywords it exports, through the C<unimport>
662 method. You simply have to say C<no Moose> at the bottom of your code for this
663 to work. Here is an example:
668 has 'first_name' => (is => 'rw', isa => 'Str');
669 has 'last_name' => (is => 'rw', isa => 'Str');
673 $self->first_name . ' ' . $self->last_name
676 no Moose; # keywords are removed from the Person package
680 =head2 What does Moose stand for??
682 Moose doesn't stand for one thing in particular. However, if you
683 want, here are a few of my favorites; feel free to contribute
688 =item Make Other Object Systems Envious
690 =item Makes Object Orientation So Easy
692 =item Makes Object Orientation Spiffy- Er (sorry ingy)
694 =item Most Other Object Systems Emasculate
696 =item Moose Often Ovulate Sorta Early
698 =item Moose Offers Often Super Extensions
700 =item Meta Object Orientation Syntax Extensions
710 It should be noted that C<super> and C<inner> B<cannot> be used in the same
711 method. However, they may be combined within the same class hierarchy; see
712 F<t/014_override_augment_inner_super.t> for an example.
714 The reason for this is that C<super> is only valid within a method
715 with the C<override> modifier, and C<inner> will never be valid within an
716 C<override> method. In fact, C<augment> will skip over any C<override> methods
717 when searching for its appropriate C<inner>.
719 This might seem like a restriction, but I am of the opinion that keeping these
720 two features separate (yet interoperable) actually makes them easy to use, since
721 their behavior is then easier to predict. Time will tell whether I am right or
726 =head1 ACKNOWLEDGEMENTS
730 =item I blame Sam Vilain for introducing me to the insanity that is meta-models.
732 =item I blame Audrey Tang for then encouraging my meta-model habit in #perl6.
734 =item Without Yuval "nothingmuch" Kogman this module would not be possible,
735 and it certainly wouldn't have this name ;P
737 =item The basis of the TypeContraints module was Rob Kinyon's idea
738 originally, I just ran with it.
740 =item Thanks to mst & chansen and the whole #moose poose for all the
741 ideas/feature-requests/encouragement/bug-finding.
743 =item Thanks to David "Theory" Wheeler for meta-discussions and spelling fixes.
751 =item L<Class::MOP> documentation
753 =item The #moose channel on irc.perl.org
755 =item The Moose mailing list - moose@perl.org
757 =item L<http://forum2.org/moose/>
759 =item L<http://www.cs.utah.edu/plt/publications/oopsla04-gff.pdf>
761 This paper (suggested by lbr on #moose) was what lead to the implementation
762 of the C<super>/C<override> and C<inner>/C<augment> features. If you really
763 want to understand them, I suggest you read this.
769 All complex software has bugs lurking in it, and this module is no
770 exception. If you find a bug please either email me, or add the bug
775 Stevan Little E<lt>stevan@iinteractive.comE<gt>
777 Christian Hansen E<lt>chansen@cpan.orgE<gt>
779 Yuval Kogman E<lt>nothingmuch@woobling.orgE<gt>
781 =head1 COPYRIGHT AND LICENSE
783 Copyright 2006, 2007 by Infinity Interactive, Inc.
785 L<http://www.iinteractive.com>
787 This library is free software; you can redistribute it and/or modify
788 it under the same terms as Perl itself.