fixing the type constraints
[gitmo/Moose.git] / lib / Moose.pm
CommitLineData
fcd84ca9 1
2package Moose;
3
4use strict;
5use warnings;
6
5af6a16d 7our $VERSION = '0.27';
d44714be 8our $AUTHORITY = 'cpan:STEVAN';
fcd84ca9 9
cc65ead0 10use Scalar::Util 'blessed', 'reftype';
3796382a 11use Carp 'confess';
12use Sub::Name 'subname';
13use B 'svref_2object';
fcd84ca9 14
2d562421 15use Sub::Exporter;
7f18097c 16
a8878950 17use Class::MOP 0.39;
ef1d5f4b 18
c0e30cf5 19use Moose::Meta::Class;
7415b2cb 20use Moose::Meta::TypeConstraint;
7c13858b 21use Moose::Meta::TypeCoercion;
78cd1d3b 22use Moose::Meta::Attribute;
ddd0ec20 23use Moose::Meta::Instance;
c0e30cf5 24
d67145ed 25use Moose::Meta::Role;
26
fcd84ca9 27use Moose::Object;
7415b2cb 28use Moose::Util::TypeConstraints;
a15dff8d 29
a3c7e2fe 30{
be33e4f3 31 my $CALLER;
9bcfbab1 32
33 sub init_meta {
34 my ( $class, $base_class, $metaclass ) = @_;
72bbc189 35 $base_class = $class unless defined $base_class;
9bcfbab1 36 $metaclass = 'Moose::Meta::Class' unless defined $metaclass;
37
38 confess
39 "The Metaclass $metaclass must be a subclass of Moose::Meta::Class."
40 unless $metaclass->isa('Moose::Meta::Class');
a3c7e2fe 41
a3c7e2fe 42 # make a subtype for each Moose class
9bcfbab1 43 subtype $class => as 'Object' => where { $_->isa($class) } =>
44 optimize_as { blessed( $_[0] ) && $_[0]->isa($class) }
a3c7e2fe 45 unless find_type_constraint($class);
46
47 my $meta;
9bcfbab1 48 if ( $class->can('meta') ) {
fcec2383 49 # NOTE:
9bcfbab1 50 # this is the case where the metaclass pragma
51 # was used before the 'use Moose' statement to
fcec2383 52 # override a specific class
a3c7e2fe 53 $meta = $class->meta();
9bcfbab1 54 ( blessed($meta) && $meta->isa('Moose::Meta::Class') )
55 || confess
56"You already have a &meta function, but it does not return a Moose::Meta::Class";
a3c7e2fe 57 }
58 else {
fcec2383 59 # NOTE:
9bcfbab1 60 # this is broken currently, we actually need
61 # to allow the possiblity of an inherited
62 # meta, which will not be visible until the
63 # user 'extends' first. This needs to have
64 # more intelligence to it
65 $meta = $metaclass->initialize($class);
66 $meta->add_method(
67 'meta' => sub {
68
69 # re-initialize so it inherits properly
70 $metaclass->initialize( blessed( $_[0] ) || $_[0] );
71 }
72 );
a3c7e2fe 73 }
74
75 # make sure they inherit from Moose::Object
72bbc189 76 $meta->superclasses($base_class)
9bcfbab1 77 unless $meta->superclasses();
a3c7e2fe 78 }
79
80 my %exports = (
81 extends => sub {
be33e4f3 82 my $class = $CALLER;
68117c45 83 return subname 'Moose::extends' => sub (@) {
84 confess "Must derive at least one class" unless @_;
1eaed09d 85 Class::MOP::load_class($_) for @_;
9bcfbab1 86
87 # this checks the metaclass to make sure
88 # it is correct, sometimes it can get out
1341f10c 89 # of sync when the classes are being built
90 my $meta = $class->meta->_fix_metaclass_incompatability(@_);
be33e4f3 91 $meta->superclasses(@_);
a3c7e2fe 92 };
93 },
94 with => sub {
be33e4f3 95 my $class = $CALLER;
68117c45 96 return subname 'Moose::with' => sub (@) {
db1ab48d 97 my (@roles) = @_;
68117c45 98 confess "Must specify at least one role" unless @roles;
1eaed09d 99 Class::MOP::load_class($_) for @roles;
1341f10c 100 $class->meta->_apply_all_roles(@roles);
a3c7e2fe 101 };
102 },
103 has => sub {
be33e4f3 104 my $class = $CALLER;
2c0cbef7 105 return subname 'Moose::has' => sub ($;%) {
9bcfbab1 106 my ( $name, %options ) = @_;
107 my $attrs = ( ref($name) eq 'ARRAY' ) ? $name : [ ($name) ];
108 $class->meta->_process_attribute( $_, %options ) for @$attrs;
a3c7e2fe 109 };
110 },
111 before => sub {
be33e4f3 112 my $class = $CALLER;
2c0cbef7 113 return subname 'Moose::before' => sub (@&) {
a3c7e2fe 114 my $code = pop @_;
be33e4f3 115 my $meta = $class->meta;
9bcfbab1 116 $meta->add_before_method_modifier( $_, $code ) for @_;
a3c7e2fe 117 };
118 },
119 after => sub {
be33e4f3 120 my $class = $CALLER;
2c0cbef7 121 return subname 'Moose::after' => sub (@&) {
a3c7e2fe 122 my $code = pop @_;
be33e4f3 123 my $meta = $class->meta;
9bcfbab1 124 $meta->add_after_method_modifier( $_, $code ) for @_;
a3c7e2fe 125 };
126 },
127 around => sub {
9bcfbab1 128 my $class = $CALLER;
2c0cbef7 129 return subname 'Moose::around' => sub (@&) {
a3c7e2fe 130 my $code = pop @_;
be33e4f3 131 my $meta = $class->meta;
9bcfbab1 132 $meta->add_around_method_modifier( $_, $code ) for @_;
a3c7e2fe 133 };
134 },
135 super => sub {
52c7c330 136 {
9bcfbab1 137 our %SUPER_SLOT;
138 no strict 'refs';
139 $SUPER_SLOT{$CALLER} = \*{"${CALLER}::super"};
52c7c330 140 }
9bcfbab1 141 return subname 'Moose::super' => sub { };
a3c7e2fe 142 },
143 override => sub {
be33e4f3 144 my $class = $CALLER;
2c0cbef7 145 return subname 'Moose::override' => sub ($&) {
9bcfbab1 146 my ( $name, $method ) = @_;
147 $class->meta->add_override_method_modifier( $name => $method );
a3c7e2fe 148 };
149 },
150 inner => sub {
52c7c330 151 {
9bcfbab1 152 our %INNER_SLOT;
153 no strict 'refs';
154 $INNER_SLOT{$CALLER} = \*{"${CALLER}::inner"};
52c7c330 155 }
9bcfbab1 156 return subname 'Moose::inner' => sub { };
a3c7e2fe 157 },
158 augment => sub {
be33e4f3 159 my $class = $CALLER;
2c0cbef7 160 return subname 'Moose::augment' => sub (@&) {
9bcfbab1 161 my ( $name, $method ) = @_;
162 $class->meta->add_augment_method_modifier( $name => $method );
a3c7e2fe 163 };
164 },
9bcfbab1 165
68efb014 166 # NOTE:
9bcfbab1 167 # this is experimental, but I am not
168 # happy with it. If you want to try
169 # it, you will have to uncomment it
170 # yourself.
171 # There is a really good chance that
172 # this will be deprecated, dont get
2a0f3bd3 173 # too attached
174 # self => sub {
175 # return subname 'Moose::self' => sub {};
9bcfbab1 176 # },
2a0f3bd3 177 # method => sub {
178 # my $class = $CALLER;
179 # return subname 'Moose::method' => sub {
180 # my ($name, $method) = @_;
181 # $class->meta->add_method($name, sub {
182 # my $self = shift;
183 # no strict 'refs';
184 # no warnings 'redefine';
185 # local *{$class->meta->name . '::self'} = sub { $self };
186 # $method->(@_);
187 # });
188 # };
9bcfbab1 189 # },
190
a3c7e2fe 191 confess => sub {
192 return \&Carp::confess;
193 },
194 blessed => sub {
195 return \&Scalar::Util::blessed;
66bcefc1 196 },
a3c7e2fe 197 );
3d544ed5 198
9bcfbab1 199 my $exporter = Sub::Exporter::build_exporter(
200 {
201 exports => \%exports,
202 groups => { default => [':all'] }
a3c7e2fe 203 }
9bcfbab1 204 );
205
c92c1205 206 # 1 extra level because it's called by import so there's a layer of indirection
207 sub _get_caller{
208 my $offset = 1;
209 return
210 ref $_[1] && defined $_[1]->{into}
211 ? $_[1]->{into}
212 : ref $_[1] && defined $_[1]->{into_level}
213 ? caller($offset + $_[1]->{into_level})
214 : caller($offset);
215 }
5bee491d 216
217 sub import {
c92c1205 218 $CALLER = _get_caller(@_);
ca3f34c1 219
c235cd98 220 strict->import;
9bcfbab1 221 warnings->import;
a3c7e2fe 222
223 # we should never export to main
224 return if $CALLER eq 'main';
9bcfbab1 225
226 init_meta( $CALLER, 'Moose::Object' );
227
a3c7e2fe 228 goto $exporter;
fcb7afc2 229 }
9bcfbab1 230
31f8ec72 231 sub unimport {
9bcfbab1 232 no strict 'refs';
c92c1205 233 my $class = _get_caller(@_);
9bcfbab1 234
31f8ec72 235 # loop through the exports ...
9bcfbab1 236 foreach my $name ( keys %exports ) {
237
31f8ec72 238 # if we find one ...
9bcfbab1 239 if ( defined &{ $class . '::' . $name } ) {
240 my $keyword = \&{ $class . '::' . $name };
241
31f8ec72 242 # make sure it is from Moose
9bcfbab1 243 my $pkg_name =
244 eval { svref_2object($keyword)->GV->STASH->NAME };
31f8ec72 245 next if $@;
246 next if $pkg_name ne 'Moose';
9bcfbab1 247
31f8ec72 248 # and if it is from Moose then undef the slot
9bcfbab1 249 delete ${ $class . '::' }{$name};
31f8ec72 250 }
251 }
252 }
9bcfbab1 253
fcd84ca9 254}
255
8ecb1fa0 256## make 'em all immutable
257
258$_->meta->make_immutable(
259 inline_constructor => 0,
77a18c28 260 inline_accessors => 1, # these are Class::MOP accessors, so they need inlining
9bcfbab1 261 )
262 for (
8ecb1fa0 263 'Moose::Meta::Attribute',
264 'Moose::Meta::Class',
265 'Moose::Meta::Instance',
266
267 'Moose::Meta::TypeConstraint',
268 'Moose::Meta::TypeConstraint::Union',
0fbd4b0a 269 'Moose::Meta::TypeConstraint::Parameterized',
8ecb1fa0 270 'Moose::Meta::TypeCoercion',
271
272 'Moose::Meta::Method',
273 'Moose::Meta::Method::Accessor',
274 'Moose::Meta::Method::Constructor',
9bcfbab1 275 'Moose::Meta::Method::Destructor',
8ecb1fa0 276 'Moose::Meta::Method::Overriden',
d67145ed 277
278 'Moose::Meta::Role',
9bcfbab1 279 'Moose::Meta::Role::Method',
280 'Moose::Meta::Role::Method::Required',
281 );
8ecb1fa0 282
fcd84ca9 2831;
284
285__END__
286
287=pod
288
289=head1 NAME
290
31f8ec72 291Moose - A complete modern object system for Perl 5
fcd84ca9 292
293=head1 SYNOPSIS
e522431d 294
295 package Point;
1cd45431 296 use Moose; # automatically turns on strict and warnings
e522431d 297
43d599e5 298 has 'x' => (is => 'rw', isa => 'Int');
299 has 'y' => (is => 'rw', isa => 'Int');
e522431d 300
301 sub clear {
302 my $self = shift;
303 $self->x(0);
304 $self->y(0);
305 }
306
307 package Point3D;
308 use Moose;
309
310 extends 'Point';
09fdc1dc 311
43d599e5 312 has 'z' => (is => 'rw', isa => 'Int');
e522431d 313
314 after 'clear' => sub {
315 my $self = shift;
43d599e5 316 $self->z(0);
734d1752 317 };
2c0cbef7 318
fcd84ca9 319=head1 DESCRIPTION
320
e522431d 321Moose is an extension of the Perl 5 object system.
322
323=head2 Another object system!?!?
fcd84ca9 324
e522431d 325Yes, I know there has been an explosion recently of new ways to
68efb014 326build object's in Perl 5, most of them based on inside-out objects
e522431d 327and other such things. Moose is different because it is not a new
328object system for Perl 5, but instead an extension of the existing
329object system.
3c7278fb 330
e522431d 331Moose is built on top of L<Class::MOP>, which is a metaclass system
332for Perl 5. This means that Moose not only makes building normal
505c6fac 333Perl 5 objects better, but it also provides the power of metaclass
334programming.
e522431d 335
734d1752 336=head2 Is this for real? Or is this just an experiment?
e522431d 337
2c0cbef7 338Moose is I<based> on the prototypes and experiments I did for the Perl 6
1cd45431 339meta-model. However, Moose is B<NOT> an experiment/prototype; it is for B<real>.
734d1752 340
d44714be 341=head2 Is this ready for use in production?
342
343Yes, I believe that it is.
734d1752 344
77a18c28 345Moose has been used successfully in production environemnts by several people
346and companies (including the one I work for). There are Moose applications
347which have been in production with little or no issue now for over a year.
348I consider it highly stable and we are commited to keeping it stable.
e522431d 349
d44714be 350Of course, in the end, you need to make this call yourself. If you have
351any questions or concerns, please feel free to email me, or even the list
352or just stop by #moose and ask away.
353
43d599e5 354=head2 Is Moose just Perl 6 in Perl 5?
e522431d 355
68efb014 356No. While Moose is very much inspired by Perl 6, it is not itself Perl 6.
1cd45431 357Instead, it is an OO system for Perl 5. I built Moose because I was tired of
68efb014 358writing the same old boring Perl 5 OO code, and drooling over Perl 6 OO. So
359instead of switching to Ruby, I wrote Moose :)
3c7278fb 360
6ba6d68c 361=head1 BUILDING CLASSES WITH MOOSE
362
68efb014 363Moose makes every attempt to provide as much convenience as possible during
364class construction/definition, but still stay out of your way if you want it
365to. Here are a few items to note when building classes with Moose.
6ba6d68c 366
367Unless specified with C<extends>, any class which uses Moose will
368inherit from L<Moose::Object>.
369
1cd45431 370Moose will also manage all attributes (including inherited ones) that are
371defined with C<has>. And (assuming you call C<new>, which is inherited from
372L<Moose::Object>) this includes properly initializing all instance slots,
373setting defaults where appropriate, and performing any type constraint checking
374or coercion.
6ba6d68c 375
376=head1 EXPORTED FUNCTIONS
377
68efb014 378Moose will export a number of functions into the class's namespace which
1cd45431 379may then be used to set up the class. These functions all work directly
6ba6d68c 380on the current class.
381
382=over 4
383
384=item B<meta>
385
386This is a method which provides access to the current class's metaclass.
387
388=item B<extends (@superclasses)>
389
390This function will set the superclass(es) for the current class.
391
392This approach is recommended instead of C<use base>, because C<use base>
393actually C<push>es onto the class's C<@ISA>, whereas C<extends> will
394replace it. This is important to ensure that classes which do not have
68efb014 395superclasses still properly inherit from L<Moose::Object>.
6ba6d68c 396
43d599e5 397=item B<with (@roles)>
e9ec68d6 398
43d599e5 399This will apply a given set of C<@roles> to the local class. Role support
68efb014 400is currently under heavy development; see L<Moose::Role> for more details.
e9ec68d6 401
cd7eeaf5 402=item B<has $name =E<gt> %options>
6ba6d68c 403
404This will install an attribute of a given C<$name> into the current class.
1cd45431 405The C<%options> are the same as those provided by
43d599e5 406L<Class::MOP::Attribute>, in addition to the list below which are provided
407by Moose (L<Moose::Meta::Attribute> to be more specific):
6ba6d68c 408
409=over 4
410
076c81ed 411=item I<is =E<gt> 'rw'|'ro'>
6ba6d68c 412
413The I<is> option accepts either I<rw> (for read/write) or I<ro> (for read
414only). These will create either a read/write accessor or a read-only
415accessor respectively, using the same name as the C<$name> of the attribute.
416
1cd45431 417If you need more control over how your accessors are named, you can use the
418I<reader>, I<writer> and I<accessor> options inherited from
419L<Class::MOP::Attribute>.
6ba6d68c 420
076c81ed 421=item I<isa =E<gt> $type_name>
6ba6d68c 422
423The I<isa> option uses Moose's type constraint facilities to set up runtime
424type checking for this attribute. Moose will perform the checks during class
425construction, and within any accessors. The C<$type_name> argument must be a
1cd45431 426string. The string may be either a class name or a type defined using
9cca2e9e 427Moose's type definition features. (Refer to L<Moose::Util::TypeConstraints>
c2a69ef1 428for information on how to define a new type, and how to retrieve type meta-data).
6ba6d68c 429
daea75c9 430=item I<coerce =E<gt> (1|0)>
431
432This will attempt to use coercion with the supplied type constraint to change
68efb014 433the value passed into any accessors or constructors. You B<must> have supplied
daea75c9 434a type constraint in order for this to work. See L<Moose::Cookbook::Recipe5>
1cd45431 435for an example.
daea75c9 436
437=item I<does =E<gt> $role_name>
438
439This will accept the name of a role which the value stored in this attribute
440is expected to have consumed.
441
442=item I<required =E<gt> (1|0)>
443
ab859145 444This marks the attribute as being required. This means a I<defined> value must be
445supplied during class construction, and the attribute may never be set to
446C<undef> with an accessor.
daea75c9 447
448=item I<weak_ref =E<gt> (1|0)>
449
68efb014 450This will tell the class to store the value of this attribute as a weakened
451reference. If an attribute is a weakened reference, it B<cannot> also be
452coerced.
daea75c9 453
454=item I<lazy =E<gt> (1|0)>
455
68efb014 456This will tell the class to not create this slot until absolutely necessary.
daea75c9 457If an attribute is marked as lazy it B<must> have a default supplied.
458
9e93dd19 459=item I<auto_deref =E<gt> (1|0)>
460
68efb014 461This tells the accessor whether to automatically dereference the value returned.
1cd45431 462This is only legal if your C<isa> option is either C<ArrayRef> or C<HashRef>.
9e93dd19 463
c1935ade 464=item I<metaclass =E<gt> $metaclass_name>
465
1cd45431 466This tells the class to use a custom attribute metaclass for this particular
467attribute. Custom attribute metaclasses are useful for extending the
468capabilities of the I<has> keyword: they are the simplest way to extend the MOP,
469but they are still a fairly advanced topic and too much to cover here. I will
470try and write a recipe on them soon.
471
472The default behavior here is to just load C<$metaclass_name>; however, we also
473have a way to alias to a shorter name. This will first look to see if
474B<Moose::Meta::Attribute::Custom::$metaclass_name> exists. If it does, Moose
475will then check to see if that has the method C<register_implemenetation>, which
476should return the actual name of the custom attribute metaclass. If there is no
477C<register_implemenetation> method, it will fall back to using
c1935ade 478B<Moose::Meta::Attribute::Custom::$metaclass_name> as the metaclass name.
479
daea75c9 480=item I<trigger =E<gt> $code>
481
1cd45431 482The I<trigger> option is a CODE reference which will be called after the value of
483the attribute is set. The CODE ref will be passed the instance itself, the
daea75c9 484updated value and the attribute meta-object (this is for more advanced fiddling
1cd45431 485and can typically be ignored). You B<cannot> have a trigger on a read-only
486attribute.
daea75c9 487
c84f324f 488=item I<handles =E<gt> ARRAY | HASH | REGEXP | ROLE | CODE>
2c0cbef7 489
1cd45431 490The I<handles> option provides Moose classes with automated delegation features.
491This is a pretty complex and powerful option. It accepts many different option
492formats, each with its own benefits and drawbacks.
38e3283b 493
1cd45431 494B<NOTE:> This feature is no longer experimental, but it may still have subtle
495bugs lurking in the deeper corners. If you think you have found a bug, you
fd595040 496probably have, so please report it to me right away.
38e3283b 497
1cd45431 498B<NOTE:> The class being delegated to does not need to be a Moose based class,
499which is why this feature is especially useful when wrapping non-Moose classes.
38e3283b 500
1cd45431 501All I<handles> option formats share the following traits:
38e3283b 502
1cd45431 503You cannot override a locally defined method with a delegated method; an
504exception will be thrown if you try. That is to say, if you define C<foo> in
505your class, you cannot override it with a delegated C<foo>. This is almost never
506something you would want to do, and if it is, you should do it by hand and not
507use Moose.
38e3283b 508
1cd45431 509You cannot override any of the methods found in Moose::Object, or the C<BUILD>
510and C<DEMOLISH> methods. These will not throw an exception, but will silently
511move on to the next method in the list. My reasoning for this is that you would
512almost never want to do this, since it usually breaks your class. As with
513overriding locally defined methods, if you do want to do this, you should do it
514manually, not with Moose.
38e3283b 515
516Below is the documentation for each option format:
517
518=over 4
519
520=item C<ARRAY>
521
1cd45431 522This is the most common usage for I<handles>. You basically pass a list of
38e3283b 523method names to be delegated, and Moose will install a delegation method
1cd45431 524for each one.
38e3283b 525
526=item C<HASH>
527
1cd45431 528This is the second most common usage for I<handles>. Instead of a list of
529method names, you pass a HASH ref where each key is the method name you
530want installed locally, and its value is the name of the original method
3dd4490b 531in the class being delegated to.
fd595040 532
1cd45431 533This can be very useful for recursive classes like trees. Here is a
fd595040 534quick example (soon to be expanded into a Moose::Cookbook::Recipe):
38e3283b 535
1cd45431 536 package Tree;
38e3283b 537 use Moose;
538
539 has 'node' => (is => 'rw', isa => 'Any');
540
541 has 'children' => (
542 is => 'ro',
543 isa => 'ArrayRef',
544 default => sub { [] }
545 );
546
547 has 'parent' => (
548 is => 'rw',
549 isa => 'Tree',
550 is_weak_ref => 1,
551 handles => {
552 parent_node => 'node',
553 siblings => 'children',
554 }
555 );
556
1cd45431 557In this example, the Tree package gets C<parent_node> and C<siblings> methods,
558which delegate to the C<node> and C<children> methods (respectively) of the Tree
559instance stored in the C<parent> slot.
38e3283b 560
561=item C<REGEXP>
562
563The regexp option works very similar to the ARRAY option, except that it builds
564the list of methods for you. It starts by collecting all possible methods of the
3dd4490b 565class being delegated to, then filters that list using the regexp supplied here.
38e3283b 566
567B<NOTE:> An I<isa> option is required when using the regexp option format. This
568is so that we can determine (at compile time) the method list from the class.
569Without an I<isa> this is just not possible.
570
c84f324f 571=item C<ROLE>
572
573With the role option, you specify the name of a role whose "interface" then
574becomes the list of methods to handle. The "interface" can be defined as; the
575methods of the role and any required methods of the role. It should be noted
576that this does B<not> include any method modifiers or generated attribute
577methods (which is consistent with role composition).
578
38e3283b 579=item C<CODE>
580
1cd45431 581This is the option to use when you really want to do something funky. You should
582only use it if you really know what you are doing, as it involves manual
583metaclass twiddling.
38e3283b 584
1cd45431 585This takes a code reference, which should expect two arguments. The first is the
586attribute meta-object this I<handles> is attached to. The second is the
587metaclass of the class being delegated to. It expects you to return a hash (not
588a HASH ref) of the methods you want mapped.
38e3283b 589
590=back
2c0cbef7 591
6ba6d68c 592=back
593
cd7eeaf5 594=item B<has +$name =E<gt> %options>
595
1cd45431 596This is variation on the normal attibute creator C<has> which allows you to
cd7eeaf5 597clone and extend an attribute from a superclass. Here is a quick example:
598
599 package Foo;
600 use Moose;
601
602 has 'message' => (
603 is => 'rw',
604 isa => 'Str',
605 default => 'Hello, I am a Foo'
606 );
607
608 package My::Foo;
609 use Moose;
610
611 extends 'Foo';
612
613 has '+message' => (default => 'Hello I am My::Foo');
614
1cd45431 615What is happening here is that B<My::Foo> is cloning the C<message> attribute
616from its parent class B<Foo>, retaining the C<is =E<gt> 'rw'> and C<isa =E<gt>
617'Str'> characteristics, but changing the value in C<default>.
cd7eeaf5 618
83cc9094 619This feature is restricted somewhat, so as to try and force at least I<some>
cd7eeaf5 620sanity into it. You are only allowed to change the following attributes:
621
622=over 4
623
624=item I<default>
625
626Change the default value of an attribute.
627
628=item I<coerce>
629
630Change whether the attribute attempts to coerce a value passed to it.
631
632=item I<required>
633
634Change if the attribute is required to have a value.
635
636=item I<documentation>
637
638Change the documentation string associated with the attribute.
639
83cc9094 640=item I<lazy>
641
642Change if the attribute lazily initializes the slot.
643
cd7eeaf5 644=item I<isa>
645
1cd45431 646You I<are> allowed to change the type, B<if and only if> the new type is a
647subtype of the old type.
cd7eeaf5 648
83cc9094 649=item I<handles>
650
651You are allowed to B<add> a new C<handles> definition, but you are B<not>
652allowed to I<change> one.
653
cd7eeaf5 654=back
655
076c81ed 656=item B<before $name|@names =E<gt> sub { ... }>
6ba6d68c 657
076c81ed 658=item B<after $name|@names =E<gt> sub { ... }>
6ba6d68c 659
076c81ed 660=item B<around $name|@names =E<gt> sub { ... }>
6ba6d68c 661
d8af92ae 662This three items are syntactic sugar for the before, after, and around method
663modifier features that L<Class::MOP> provides. More information on these may be
664found in the L<Class::MOP::Class documentation|Class::MOP::Class/"Method
665Modifiers"> for now.
6ba6d68c 666
159da176 667=item B<super>
668
68efb014 669The keyword C<super> is a no-op when called outside of an C<override> method. In
159da176 670the context of an C<override> method, it will call the next most appropriate
671superclass method with the same arguments as the original method.
672
673=item B<override ($name, &sub)>
674
68efb014 675An C<override> method is a way of explicitly saying "I am overriding this
159da176 676method from my superclass". You can call C<super> within this method, and
677it will work as expected. The same thing I<can> be accomplished with a normal
68efb014 678method call and the C<SUPER::> pseudo-package; it is really your choice.
159da176 679
680=item B<inner>
681
682The keyword C<inner>, much like C<super>, is a no-op outside of the context of
683an C<augment> method. You can think of C<inner> as being the inverse of
68efb014 684C<super>; the details of how C<inner> and C<augment> work is best described in
159da176 685the L<Moose::Cookbook>.
686
687=item B<augment ($name, &sub)>
688
68efb014 689An C<augment> method, is a way of explicitly saying "I am augmenting this
159da176 690method from my superclass". Once again, the details of how C<inner> and
691C<augment> work is best described in the L<Moose::Cookbook>.
692
6ba6d68c 693=item B<confess>
694
68efb014 695This is the C<Carp::confess> function, and exported here because I use it
6ba6d68c 696all the time. This feature may change in the future, so you have been warned.
697
698=item B<blessed>
699
1cd45431 700This is the C<Scalar::Util::blessed> function, it is exported here because I
6ba6d68c 701use it all the time. It is highly recommended that this is used instead of
702C<ref> anywhere you need to test for an object's class name.
703
704=back
705
1cd45431 706=head1 UNIMPORTING FUNCTIONS
31f8ec72 707
708=head2 B<unimport>
709
1cd45431 710Moose offers a way to remove the keywords it exports, through the C<unimport>
31f8ec72 711method. You simply have to say C<no Moose> at the bottom of your code for this
712to work. Here is an example:
713
714 package Person;
715 use Moose;
716
717 has 'first_name' => (is => 'rw', isa => 'Str');
718 has 'last_name' => (is => 'rw', isa => 'Str');
719
720 sub full_name {
721 my $self = shift;
722 $self->first_name . ' ' . $self->last_name
723 }
724
725 no Moose; # keywords are removed from the Person package
726
9bcfbab1 727=head1 EXTENDING AND EMBEDDING MOOSE
728
729Moose also offers some options for extending or embedding it into your own
730framework. The basic premise is to have something that sets up your class'
731metaclass and export the moose declarators (C<has>, C<with>, C<extends>,...).
732Here is an example:
733
734 package MyFramework;
735 use Moose;
736
737 sub import {
738 my $CALLER = caller();
739
740 strict->import;
741 warnings->import;
742
743 # we should never export to main
744 return if $CALLER eq 'main';
745 Moose::init_meta( $CALLER, 'MyFramework::Base' );
746 Moose->import({into => $CALLER});
747
748 # Do my custom framework stuff
749
750 return 1;
751 }
752
753=head2 B<import>
754
77a18c28 755Moose's C<import> method supports the L<Sub::Exporter> form of C<{into =E<gt> $pkg}>
9bcfbab1 756and C<{into_level =E<gt> 1}>
757
758=head2 B<init_meta ($class, $baseclass, $metaclass)>
759
760Moose does some boot strapping: it creates a metaclass object for your class,
2bbba362 761and then injects a C<meta> accessor into your class to retrieve it. Then it
762sets your baseclass to Moose::Object or the value you pass in unless you already
763have one. This is all done via C<init_meta> which takes the name of your class
764and optionally a baseclass and a metaclass as arguments.
9bcfbab1 765
05d9eaf6 766=head1 CAVEATS
767
768=over 4
769
770=item *
771
1cd45431 772It should be noted that C<super> and C<inner> B<cannot> be used in the same
773method. However, they may be combined within the same class hierarchy; see
774F<t/014_override_augment_inner_super.t> for an example.
05d9eaf6 775
68efb014 776The reason for this is that C<super> is only valid within a method
05d9eaf6 777with the C<override> modifier, and C<inner> will never be valid within an
778C<override> method. In fact, C<augment> will skip over any C<override> methods
68efb014 779when searching for its appropriate C<inner>.
05d9eaf6 780
1cd45431 781This might seem like a restriction, but I am of the opinion that keeping these
782two features separate (yet interoperable) actually makes them easy to use, since
783their behavior is then easier to predict. Time will tell whether I am right or
c84f324f 784not (UPDATE: so far so good).
05d9eaf6 785
786=back
787
5569c072 788=head1 ACKNOWLEDGEMENTS
789
790=over 4
791
54c189df 792=item I blame Sam Vilain for introducing me to the insanity that is meta-models.
5569c072 793
54c189df 794=item I blame Audrey Tang for then encouraging my meta-model habit in #perl6.
5569c072 795
076c81ed 796=item Without Yuval "nothingmuch" Kogman this module would not be possible,
54c189df 797and it certainly wouldn't have this name ;P
5569c072 798
799=item The basis of the TypeContraints module was Rob Kinyon's idea
800originally, I just ran with it.
801
076c81ed 802=item Thanks to mst & chansen and the whole #moose poose for all the
c84f324f 803early ideas/feature-requests/encouragement/bug-finding.
d46a48f3 804
68efb014 805=item Thanks to David "Theory" Wheeler for meta-discussions and spelling fixes.
806
5569c072 807=back
808
e90c03d0 809=head1 SEE ALSO
810
811=over 4
812
c84f324f 813=item L<http://www.iinteractive.com/moose>
814
815This is the official web home of Moose, it contains links to our public SVN repo
816as well as links to a number of talks and articles on Moose and Moose related
817technologies.
818
6ba6d68c 819=item L<Class::MOP> documentation
820
821=item The #moose channel on irc.perl.org
822
e67a0fca 823=item The Moose mailing list - moose@perl.org
824
c84f324f 825=item Moose stats on ohloh.net - L<http://www.ohloh.net/projects/5788>
826
827=back
828
829=head2 Papers
830
831=over 4
e90c03d0 832
159da176 833=item L<http://www.cs.utah.edu/plt/publications/oopsla04-gff.pdf>
834
835This paper (suggested by lbr on #moose) was what lead to the implementation
1cd45431 836of the C<super>/C<override> and C<inner>/C<augment> features. If you really
837want to understand them, I suggest you read this.
159da176 838
e90c03d0 839=back
840
fcd84ca9 841=head1 BUGS
842
843All complex software has bugs lurking in it, and this module is no
844exception. If you find a bug please either email me, or add the bug
845to cpan-RT.
846
fcd84ca9 847=head1 AUTHOR
848
849Stevan Little E<lt>stevan@iinteractive.comE<gt>
850
9af1d28b 851B<with contributions from:>
db1ab48d 852
9af1d28b 853Aankhen
854
855Adam (Alias) Kennedy
856
857Anders (Debolaz) Nor Berle
858
5868294f 859Nathan (kolibre) Gray
860
9af1d28b 861Christian (chansen) Hansen
862
e7f8d0c2 863Hans Dieter (confound) Pearcey
864
9af1d28b 865Eric (ewilhelm) Wilhelm
866
867Guillermo (groditi) Roditi
868
869Jess (castaway) Robinson
870
871Matt (mst) Trout
872
873Robert (phaylon) Sedlacek
874
875Robert (rlb3) Boone
876
877Scott (konobi) McWhirter
878
f44ae52f 879Shlomi (rindolf) Fish
880
9af1d28b 881Yuval (nothingmuch) Kogman
882
cbe25729 883Chris (perigrin) Prather
884
e46f5cc2 885Jonathan (jrockway) Rockway
886
3ccdc84a 887Piotr (dexter) Roszatycki
888
f1917f58 889Sam (mugwump) Vilain
890
9af1d28b 891... and many other #moose folks
98aae381 892
fcd84ca9 893=head1 COPYRIGHT AND LICENSE
894
b77fdbed 895Copyright 2006, 2007 by Infinity Interactive, Inc.
fcd84ca9 896
897L<http://www.iinteractive.com>
898
899This library is free software; you can redistribute it and/or modify
900it under the same terms as Perl itself.
901
ddd0ec20 902=cut