8 our $VERSION = '1.000000'; # 1.0.0
9 $VERSION = eval $VERSION;
11 require Moo::sification;
15 sub _install_tracked {
16 my ($target, $name, $code) = @_;
17 $MAKERS{$target}{exports}{$name} = $code;
18 _install_coderef "${target}::${name}" => "Moo::${name}" => $code;
25 return if $MAKERS{$target}; # already exported into this package
26 $MAKERS{$target} = {};
27 _install_tracked $target => extends => sub {
28 $class->_set_superclasses($target, @_);
29 $class->_maybe_reset_handlemoose($target);
32 _install_tracked $target => with => sub {
34 Moo::Role->apply_roles_to_package($target, @_);
35 $class->_maybe_reset_handlemoose($target);
37 _install_tracked $target => has => sub {
38 my ($name, %spec) = @_;
39 $class->_constructor_maker_for($target)
40 ->register_attribute_specs($name, \%spec);
41 $class->_accessor_maker_for($target)
42 ->generate_method($target, $name, \%spec);
43 $class->_maybe_reset_handlemoose($target);
46 foreach my $type (qw(before after around)) {
47 _install_tracked $target => $type => sub {
48 require Class::Method::Modifiers;
49 _install_modifier($target, $type, @_);
55 @{"${target}::ISA"} = do {
56 require Moo::Object; ('Moo::Object');
57 } unless @{"${target}::ISA"};
59 if ($INC{'Moo/HandleMoose.pm'}) {
60 Moo::HandleMoose::inject_fake_metaclass_for($target);
66 _unimport_coderefs($target, $MAKERS{$target});
69 sub _set_superclasses {
74 if ($INC{"Role/Tiny.pm"} && $Role::Tiny::INFO{$_}) {
76 Carp::croak("Can't extend role '$_'");
79 # Can't do *{...} = \@_ or 5.10.0's mro.pm stops seeing @ISA
80 @{*{_getglob("${target}::ISA")}{ARRAY}} = @_;
81 if (my $old = delete $Moo::MAKERS{$target}{constructor}) {
82 delete _getstash($target)->{new};
83 Moo->_constructor_maker_for($target)
84 ->register_attribute_specs(%{$old->all_attribute_specs});
86 no warnings 'once'; # piss off. -- mst
87 $Moo::HandleMoose::MOUSE{$target} = [
88 grep defined, map Mouse::Util::find_meta($_), @_
89 ] if $INC{"Mouse.pm"};
92 sub _maybe_reset_handlemoose {
93 my ($class, $target) = @_;
94 if ($INC{"Moo/HandleMoose.pm"}) {
95 Moo::HandleMoose::maybe_reinject_fake_metaclass_for($target);
99 sub _accessor_maker_for {
100 my ($class, $target) = @_;
101 return unless $MAKERS{$target};
102 $MAKERS{$target}{accessor} ||= do {
103 my $maker_class = do {
105 if (my $defer_target =
106 (Sub::Defer::defer_info($target->can('new'))||[])->[0]
108 my ($pkg) = ($defer_target =~ /^(.*)::[^:]+$/);
109 $MAKERS{$pkg} && $MAKERS{$pkg}{accessor};
116 require Method::Generate::Accessor;
117 'Method::Generate::Accessor'
124 sub _constructor_maker_for {
125 my ($class, $target, $select_super) = @_;
126 return unless $MAKERS{$target};
127 $MAKERS{$target}{constructor} ||= do {
128 require Method::Generate::Constructor;
130 my ($moo_constructor, $con);
132 if ($select_super && $MAKERS{$select_super}) {
133 $moo_constructor = 1;
134 $con = $MAKERS{$select_super}{constructor};
136 my $t_new = $target->can('new');
138 if ($t_new == Moo::Object->can('new')) {
139 $moo_constructor = 1;
140 } elsif (my $defer_target = (Sub::Defer::defer_info($t_new)||[])->[0]) {
141 my ($pkg) = ($defer_target =~ /^(.*)::[^:]+$/);
143 $moo_constructor = 1;
144 $con = $MAKERS{$pkg}{constructor};
148 $moo_constructor = 1; # no other constructor, make a Moo one
151 ($con ? ref($con) : 'Method::Generate::Constructor')
154 accessor_generator => $class->_accessor_maker_for($target),
155 construction_string => (
157 ? ($con ? $con->construction_string : undef)
158 : ('$class->'.$target.'::SUPER::new(@_)')
160 subconstructor_handler => (
161 ' if ($Moo::MAKERS{$class}) {'."\n"
162 .' '.$class.'->_constructor_maker_for($class,'.perlstring($target).');'."\n"
163 .' return $class->new(@_)'.";\n"
164 .' } elsif ($INC{"Moose.pm"} and my $meta = Class::MOP::get_metaclass_by_name($class)) {'."\n"
165 .' return $meta->new_object(@_);'."\n"
170 ->register_attribute_specs(%{$con?$con->all_attribute_specs:{}})
181 Moo - Minimalist Object Orientation (with Moose compatiblity)
191 my $amount = shift || 1;
193 $self->pounds( $self->pounds - $amount );
203 die "Only SWEET-TREATZ supported!" unless $_[0] eq 'SWEET-TREATZ'
209 isa => sub { die "$_[0] is too much cat food!" unless $_[0] < 15 },
216 my $full = Cat::Food->new(
217 taste => 'DELICIOUS.',
218 brand => 'SWEET-TREATZ',
228 This module is an extremely light-weight subset of L<Moose> optimised for
229 rapid startup and pay for what you use.
231 It also avoids depending on any XS modules to allow simple deployments. The
232 name C<Moo> is based on the idea that it provides almost -but not quite- two
235 Unlike C<Mouse> this module does not aim at full compatibility with
236 L<Moose>'s surface syntax, preferring instead of provide full interoperability
237 via the metaclass inflation capabilites described in L</MOO AND MOOSE>.
239 For a full list of the minor differences between L<Moose> and L<Moo>'s surface
240 syntax, see L</INCOMPATIBILITIES>.
242 =head1 WHY MOO EXISTS
244 If you want a full object system with a rich Metaprotocol, L<Moose> is
247 However, sometimes you're writing a command line script or a CGI script
248 where fast startup is essential, or code designed to be deployed as a single
249 file via L<App::FatPacker>, or you're writing a CPAN module and you want it
250 to be usable by people with those constraints.
252 I've tried several times to use L<Mouse> but it's 3x the size of Moo and
253 takes longer to load than most of my Moo based CGI scripts take to run.
255 If you don't want L<Moose>, you don't want "less metaprotocol" like L<Mouse>,
256 you want "as little as possible" - which means "no metaprotocol", which is
259 Better still, if you install and load L<Moose>, we set up metaclasses for your
260 L<Moo> classes and L<Moo::Role> roles, so you can use them in L<Moose> code
261 without ever noticing that some of your codebase is using L<Moo>.
263 Hence - Moo exists as its name - Minimal Object Orientation - with a pledge
264 to make it smooth to upgrade to L<Moose> when you need more than minimal
269 If L<Moo> detects L<Moose> being loaded, it will automatically register
270 metaclasses for your L<Moo> and L<Moo::Role> packages, so you should be able
271 to use them in L<Moose> code without anybody ever noticing you aren't using
274 Extending a L<Moose> class or consuming a L<Moose::Role> will also work.
276 So will extending a L<Mouse> class or consuming a L<Mouse::Role> - but note
277 that we don't provide L<Mouse> metaclasses or metaroles so the other way
278 around doesn't work. This feature exists for L<Any::Moose> users porting to
279 L<Moo>, enabling L<Mouse> users to use L<Moo> classes is not a priority for us.
281 This means that there is no need for anything like L<Any::Moose> for Moo
282 code - Moo and Moose code should simply interoperate without problem. To
283 handle L<Mouse> code, you'll likely need an empty Moo role or class consuming
284 or extending the L<Mouse> stuff since it doesn't register true L<Moose>
285 metaclasses like L<Moo> does.
287 If you want types to be upgraded to the L<Moose> types, use
288 L<MooX::Types::MooseLike> and install the L<MooseX::Types> library to
289 match the L<MooX::Types::MooseLike> library you're using - L<Moo> will
290 load the L<MooseX::Types> library and use that type for the newly created
293 If you need to disable the metaclass creation, add:
297 to your code before Moose is loaded, but bear in mind that this switch is
298 currently global and turns the mechanism off entirely so don't put this
301 =head1 IMPORTED METHODS
305 Foo::Bar->new( attr1 => 3 );
309 Foo::Bar->new({ attr1 => 3 });
314 my ( $class, @args ) = @_;
316 unshift @args, "attr1" if @args % 2 == 1;
323 The default implementation of this method accepts a hash or hash reference of
324 named parameters. If it receives a single argument that isn't a hash reference
327 You can override this method in your class to handle other types of options
328 passed to the constructor.
330 This method should always return a hash reference of named options.
334 Define a C<BUILD> method on your class and the constructor will automatically
335 call the C<BUILD> method from parent down to child after the object has
336 been instantiated. Typically this is used for object validation or possibly
341 If you have a C<DEMOLISH> method anywhere in your inheritance hierarchy,
342 a C<DESTROY> method is created on first object construction which will call
343 C<< $instance->DEMOLISH($in_global_destruction) >> for each C<DEMOLISH>
344 method from child upwards to parents.
346 Note that the C<DESTROY> method is created on first construction of an object
347 of your class in order to not add overhead to classes without C<DEMOLISH>
348 methods; this may prove slightly surprising if you try and define your own.
352 if ($foo->does('Some::Role1')) {
356 Returns true if the object composes in the passed role.
358 =head1 IMPORTED SUBROUTINES
362 extends 'Parent::Class';
364 Declares base class. Multiple superclasses can be passed for multiple
365 inheritance (but please use roles instead).
367 Calling extends more than once will REPLACE your superclasses, not add to
368 them like 'use base' would.
376 with 'Some::Role1', 'Some::Role2';
378 Composes one or more L<Moo::Role> (or L<Role::Tiny>) roles into the current
379 class. An error will be raised if these roles have conflicting methods.
387 Declares an attribute for the class.
389 The options for C<has> are as follows:
395 B<required>, may be C<ro>, C<lazy>, C<rwp> or C<rw>.
397 C<ro> generates an accessor that dies if you attempt to write to it - i.e.
398 a getter only - by defaulting C<reader> to the name of the attribute.
400 C<lazy> generates a reader like C<ro>, but also sets C<lazy> to 1 and
401 C<builder> to C<_build_${attribute_name}> to allow on-demand generated
402 attributes. This feature was my attempt to fix my incompetence when
403 originally designing C<lazy_build>, and is also implemented by
404 L<MooseX::AttributeShortcuts>.
406 C<rwp> generates a reader like C<ro>, but also sets C<writer> to
407 C<_set_${attribute_name}> for attributes that are designed to be written
408 from inside of the class, but read-only from outside.
409 This feature comes from L<MooseX::AttributeShortcuts>.
411 C<rw> generates a normal getter/setter by defaulting C<accessor> to the
412 name of the attribute.
416 Takes a coderef which is meant to validate the attribute. Unlike L<Moose> Moo
417 does not include a basic type system, so instead of doing C<< isa => 'Num' >>,
421 die "$_[0] is not a number!" unless looks_like_number $_[0]
424 L<Sub::Quote aware|/SUB QUOTE AWARE>
426 Since L<Moo> does B<not> run the C<isa> check before C<coerce> if a coercion
427 subroutine has been supplied, C<isa> checks are not structural to your code
428 and can, if desired, be omitted on non-debug builds (although if this results
429 in an uncaught bug causing your program to break, the L<Moo> authors guarantee
430 nothing except that you get to keep both halves).
432 If you want L<MooseX::Types> style named types, look at
433 L<MooX::Types::MooseLike>.
435 To cause your C<isa> entries to be automatically mapped to named
436 L<Moose::Meta::TypeConstraint> objects (rather than the default behaviour
437 of creating an anonymous type), set:
439 $Moo::HandleMoose::TYPE_MAP{$isa_coderef} = sub {
440 require MooseX::Types::Something;
441 return MooseX::Types::Something::TypeName();
444 Note that this example is purely illustrative; anything that returns a
445 L<Moose::Meta::TypeConstraint> object or something similar enough to it to
446 make L<Moose> happy is fine.
450 Takes a coderef which is meant to coerce the attribute. The basic idea is to
451 do something like the following:
454 $_[0] + 1 unless $_[0] % 2
457 Note that L<Moo> will always fire your coercion - this is to permit
458 isa entries to be used purely for bug trapping, whereas coercions are
459 always structural to your code. We do, however, apply any supplied C<isa>
460 check after the coercion has run to ensure that it returned a valid value.
462 L<Sub::Quote aware|/SUB QUOTE AWARE>
468 handles => 'RobotRole'
470 Where C<RobotRole> is a role (L<Moo::Role>) that defines an interface which
471 becomes the list of methods to handle.
473 Takes a list of methods
475 handles => [ qw( one two ) ]
485 Takes a coderef which will get called any time the attribute is set. This
486 includes the constructor. Coderef will be invoked against the object with the
487 new value as an argument.
489 If you set this to just C<1>, it generates a trigger which calls the
490 C<_trigger_${attr_name}> method on C<$self>. This feature comes from
491 L<MooseX::AttributeShortcuts>.
493 Note that Moose also passes the old value, if any; this feature is not yet
496 L<Sub::Quote aware|/SUB QUOTE AWARE>
500 Takes a coderef which will get called with $self as its only argument
501 to populate an attribute if no value is supplied to the constructor - or
502 if the attribute is lazy, when the attribute is first retrieved if no
503 value has yet been provided.
505 Note that if your default is fired during new() there is no guarantee that
506 other attributes have been populated yet so you should not rely on their
509 L<Sub::Quote aware|/SUB QUOTE AWARE>
513 Takes a method name which will return true if an attribute has a value.
515 If you set this to just C<1>, the predicate is automatically named
516 C<has_${attr_name}> if your attribute's name does not start with an
517 underscore, or <_has_${attr_name_without_the_underscore}> if it does.
518 This feature comes from L<MooseX::AttributeShortcuts>.
522 Takes a method name which will be called to create the attribute - functions
523 exactly like default except that instead of calling
531 If you set this to just C<1>, the predicate is automatically named
532 C<_build_${attr_name}>. This feature comes from L<MooseX::AttributeShortcuts>.
536 Takes a method name which will clear the attribute.
538 If you set this to just C<1>, the clearer is automatically named
539 C<clear_${attr_name}> if your attribute's name does not start with an
540 underscore, or <_clear_${attr_name_without_the_underscore}> if it does.
541 This feature comes from L<MooseX::AttributeShortcuts>.
545 B<Boolean>. Set this if you want values for the attribute to be grabbed
546 lazily. This is usually a good idea if you have a L</builder> which requires
547 another attribute to be set.
551 B<Boolean>. Set this if the attribute must be passed on instantiation.
555 The value of this attribute will be the name of the method to get the value of
556 the attribute. If you like Java style methods, you might set this to
561 The value of this attribute will be the name of the method to set the value of
562 the attribute. If you like Java style methods, you might set this to
567 B<Boolean>. Set this if you want the reference that the attribute contains to
568 be weakened; use this when circular references are possible, which will cause
573 Takes the name of the key to look for at instantiation time of the object. A
574 common use of this is to make an underscored attribute have a non-underscored
575 initialization name. C<undef> means that passing the value in on instantiation
582 before foo => sub { ... };
584 See L<< Class::Method::Modifiers/before method(s) => sub { ... } >> for full
589 around foo => sub { ... };
591 See L<< Class::Method::Modifiers/around method(s) => sub { ... } >> for full
596 after foo => sub { ... };
598 See L<< Class::Method::Modifiers/after method(s) => sub { ... } >> for full
601 =head1 SUB QUOTE AWARE
603 L<Sub::Quote/quote_sub> allows us to create coderefs that are "inlineable,"
604 giving us a handy, XS-free speed boost. Any option that is L<Sub::Quote>
605 aware can take advantage of this.
607 To do this, you can write
613 is => quote_sub(q{ die "Not <3" unless $_[0] < 3 })
616 which will be inlined as
619 local @_ = ($_[0]->{foo});
620 die "Not <3" unless $_[0] < 3;
623 or to avoid localizing @_,
626 is => quote_sub(q{ my ($val) = @_; die "Not <3" unless $val < 3 })
629 which will be inlined as
632 my ($val) = ($_[0]->{foo});
633 die "Not <3" unless $val < 3;
636 See L<Sub::Quote> for more information, including how to pass lexical
637 captures that will also be compiled in to the subroutine.
639 =head1 INCOMPATIBILITIES WITH MOOSE
641 There is no built in type system. C<isa> is verified with a coderef, if you
642 need complex types, just make a library of coderefs, or better yet, functions
643 that return quoted subs. L<MooX::Types::MooseLike> provides a similar API
644 to L<MooseX::Types::Moose> so that you can write
646 has days_to_live => (is => 'ro', isa => Int);
648 and have it work with both; it is hoped that providing only subrefs as an
649 API will encourage the use of other type systems as well, since it's
650 probably the weakest part of Moose design-wise.
652 C<initializer> is not supported in core since the author considers it to be a
653 bad idea but may be supported by an extension in future. Meanwhile C<trigger> or
654 C<coerce> are more likely to be able to fulfill your needs.
656 There is no meta object. If you need this level of complexity you wanted
657 L<Moose> - Moo succeeds at being small because it explicitly does not
658 provide a metaprotocol. However, if you load L<Moose>, then
660 Class::MOP::class_of($moo_class_or_role)
662 will return an appropriate metaclass pre-populated by L<Moo>.
664 No support for C<super>, C<override>, C<inner>, or C<augment> - the author
665 considers augment to be a bad idea, and override can be translated:
667 override foo => sub {
674 my ($orig, $self) = (shift, shift);
680 The C<dump> method is not provided by default. The author suggests loading
681 L<Devel::Dwarn> into C<main::> (via C<perl -MDevel::Dwarn ...> for example) and
682 using C<$obj-E<gt>$::Dwarn()> instead.
684 L</default> only supports coderefs, because doing otherwise is usually a
687 C<lazy_build> is not supported; you are instead encouraged to use the
688 C<is => 'lazy'> option supported by L<Moo> and L<MooseX::AttributeShortcuts>.
690 C<auto_deref> is not supported since the author considers it a bad idea.
692 C<documentation> will show up in a L<Moose> metaclass created from your class
693 but is otherwise ignored. Then again, L<Moose> ignores it as well, so this
694 is arguably not an incompatibility.
696 Since C<coerce> does not require C<isa> to be defined but L<Moose> does
697 require it, the metaclass inflation for coerce-alone is a trifle insane
698 and if you attempt to subtype the result will almost certainly break.
700 Handling of warnings: when you C<use Moo> we enable FATAL warnings. The nearest
701 similar invocation for L<Moose> would be:
704 use warnings FATAL => "all";
706 Additionally, L<Moo> supports a set of attribute option shortcuts intended to
707 reduce common boilerplate. The set of shortcuts is the same as in the L<Moose>
708 module L<MooseX::AttributeShortcuts> as of its version 0.009+. So if you:
713 The nearest L<Moose> invocation would be:
718 use warnings FATAL => "all";
719 use MooseX::AttributeShortcuts;
721 or, if you're inheriting from a non-Moose class,
726 use MooseX::NonMoose;
727 use warnings FATAL => "all";
728 use MooseX::AttributeShortcuts;
730 Finally, Moose requires you to call
732 __PACKAGE__->meta->make_immutable;
734 at the end of your class to get an inlined (i.e. not horribly slow)
735 constructor. Moo does it automatically the first time ->new is called
740 Users' IRC: #moose on irc.perl.org
742 Development and contribution IRC: #web-simple on irc.perl.org
746 mst - Matt S. Trout (cpan:MSTROUT) <mst@shadowcat.co.uk>
750 dg - David Leadbeater (cpan:DGL) <dgl@dgl.cx>
752 frew - Arthur Axel "fREW" Schmidt (cpan:FREW) <frioux@gmail.com>
754 hobbs - Andrew Rodland (cpan:ARODLAND) <arodland@cpan.org>
756 jnap - John Napiorkowski (cpan:JJNAPIORK) <jjn1056@yahoo.com>
758 ribasushi - Peter Rabbitson (cpan:RIBASUSHI) <ribasushi@cpan.org>
760 chip - Chip Salzenberg (cpan:CHIPS) <chip@pobox.com>
762 ajgb - Alex J. G. Burzyński (cpan:AJGB) <ajgb@cpan.org>
764 doy - Jesse Luehrs (cpan:DOY) <doy at tozt dot net>
766 perigrin - Chris Prather (cpan:PERIGRIN) <chris@prather.org>
768 Mithaldu - Christian Walde (cpan:MITHALDU) <walde.christian@googlemail.com>
770 ilmari - Dagfinn Ilmari Mannsåker (cpan:ILMARI) <ilmari@ilmari.org>
774 Copyright (c) 2010-2011 the Moo L</AUTHOR> and L</CONTRIBUTORS>
779 This library is free software and may be distributed under the same terms