5 Moose::Manual::Delta - Important Changes in Moose
9 This documents any important or noteworthy changes in Moose, with a
10 focus on backwards. This does duplicate data from the F<Changes> file,
11 but aims to provide more details and when possible workarounds.
13 Besides helping keep up with changes, you can also use this document
14 for finding the lowest version of Moose that supported a given
15 feature. If you encounter a problem and have a solution but don't see
16 it documented here, or think we missed an important feature, please
21 L<Moose::Meta::Attribute::Native> has been moved into the Moose core from
22 L<MooseX::AttributeHelpers>. Major changes include:
26 =item C<traits>, not C<metaclass>
28 Method providers are only available via traits.
30 =item C<handles>, not C<provides> or C<curries>
32 The C<provides> syntax was like core Moose C<< handles => HASHREF >>
33 syntax, but with the keys and values reversed. This was confusing,
34 and AttributeHelpers now uses C<< handles => HASHREF >> in a way that
35 should be intuitive to anyone already familiar with how it is used for
38 The C<curries> functionality provided by AttributeHelpers has been
39 generalized to apply to all cases of C<< handles => HASHREF >>, though
40 not every piece of functionality has been ported (currying with a
41 CODEREF is not supported).
43 =item C<empty> now means empty, not non-empty
45 Previously, the C<empty> method provided by Arrays and Hashes returned true if
46 the attribute was B<not> empty (no elements). Now it returns true if the
47 attribute B<is> empty.
49 =item C<find> was renamed to C<first>, and C<first> was renamed to C<head>
51 L<List::Util> refers to the functionality that we used to provide under C<find>
52 as L<first|List::Util/first>, so that will likely be more familiar (and will
53 fit in better if we decide to add more List::Util functions). C<head> is an
54 obvious choice to replace what used to be called C<first>.
56 =item Helpers that take a coderef of one argument now use C<$_>
58 Subroutines passed as the first argument to C<first>, C<map>, and C<grep> now
59 receive their argument in C<$_> rather than as a parameter to the subroutine.
60 Helpers that take a coderef of two or more arguments remain using the argument
61 list (there are technical limitations to using C<$a> and C<$b> like C<sort>
66 See L<Moose::Meta::Attribute::Native> for the new documentation.
68 C<< use Moose -metaclass => 'Foo' >> now does alias resolution, just like
69 C<-traits> (and the C<metaclass> and C<traits> options to C<has>).
71 Added two functions C<meta_class_alias> and C<meta_attribute_alias> to
72 L<Moose::Util>, to simplify aliasing metaclasses and metatraits. This is
73 a wrapper around the old
75 package Moose::Meta::Class::Custom::Trait::FooTrait;
76 sub register_implementation { 'My::Meta::Trait' }
80 The C<alias> and C<excludes> role parameters have been renamed to C<-alias>
81 and C<-excludes>. The old names still work, but new code should use the new
82 names, and eventually the old ones will be deprecated and removed.
86 When an attribute generates I<no> accessors, we now warn. This is to help
87 users who forget the C<is> option. If you really do not want any accessors,
88 you can use C<< is => 'bare' >>. You can maintain back compat with older
89 versions of Moose by using something like:
91 ($Moose::VERSION >= 0.84 ? is => 'bare' : ())
93 When an accessor overwrites an existing method, we now warn. To work around
94 this warning (if you really must have this behavior), you can explicitly
95 remove the method before creating it as an accessor:
99 __PACKAGE__->meta->remove_method('foo');
105 When an unknown option is passed to C<has>, we now warn. You can silence
106 the warning by fixing your code. :)
108 The C<Role> type has been deprecated. On its own, it was useless,
109 since it just checked C<< $object->can('does') >>. If you were using
110 it as a parent type, just call C<role_type('Role::Name')> to create an
111 appropriate type instead.
115 C<use Moose::Exporter;> now imports C<strict> and C<warnings> into packages
120 C<DEMOLISHALL> and C<DEMOLISH> now receive an argument indicating whether or
121 not we are in global destruction.
125 Type constraints no longer run coercions for a value that already matches the
126 constraint. This may affect some (arguably buggy) edge case coercions that
127 rely on side effects in the C<via> clause.
131 L<Moose::Exporter> now accepts the C<-metaclass> option for easily
132 overriding the metaclass (without L<metaclass>). This works for classes
137 Added a C<duck_type> sugar function to L<Moose::Util::TypeConstraints>
138 to make integration with non-Moose classes easier. It simply checks if
139 C<< $obj->can() >> a list of methods.
141 A number of methods (mostly inherited from L<Class::MOP>) have been
142 renamed with a leading underscore to indicate their internal-ness. The
143 old method names will still work for a while, but will warn that the
144 method has been renamed. In a few cases, the method will be removed
145 entirely in the future. This may affect MooseX authors who were using
150 Calling C<subtype> with a name as the only argument now throws an
151 exception. If you want an anonymous subtype do:
153 my $subtype = subtype as 'Foo';
155 This is related to the changes in version 0.71_01.
157 The C<is_needed> method in L<Moose::Meta::Method::Destructor> is now
158 only usable as a class method. Previously, it worked as a class or
159 object method, with a different internal implementation for each
162 The internals of making a class immutable changed a lot in Class::MOP
163 0.78_02, and Moose's internals have changed along with it. The
164 external C<< $metaclass->make_immutable >> method still works the same
169 A mutable class accepted C<< Foo->new(undef) >> without complaint,
170 while an immutable class would blow up with an unhelpful error. Now,
171 in both cases we throw a helpful error instead.
173 This "feature" was originally added to allow for cases such as this:
181 return My::Class->new($args);
183 But we decided this is a bad idea and a little too magical, because it
184 can easily mask real errors.
186 =head1 Version 0.71_01
188 Calling C<type> or C<subtype> without the sugar helpers (C<as>,
189 C<where>, C<message>) is now deprecated.
191 As a side effect, this meant we ended up using Perl prototypes on
192 C<as>, and code like this will no longer work:
194 use Moose::Util::TypeConstraints;
195 use Declare::Constraints::Simple -All;
197 subtype 'ArrayOfInts'
199 => IsArrayRef(IsInt);
201 Instead it must be changed to this:
206 where => IsArrayRef(IsInt)
210 If you want to maintain backwards compat with older versions of Moose,
211 you must explicitly test Moose's C<VERSION>:
213 if ( Moose->VERSION < 0.71_01 ) {
214 subtype 'ArrayOfInts'
216 => IsArrayRef(IsInt);
222 where => IsArrayRef(IsInt)
229 We no longer pass the meta-attribute object as a final argument to
230 triggers. This actually changed for inlined code a while back, but the
231 non-inlined version and the docs were still out of date.
233 If by some chance you actually used this feature, the workaround is
234 simple. You fetch the attribute object from out of the C<$self>
235 that is passed as the first argument to trigger, like so:
241 my ( $self, $value ) = @_;
242 my $attr = $self->meta->find_attribute_by_name('foo');
250 If you created a subtype and passed a parent that Moose didn't know
251 about, it simply ignored the parent. Now it automatically creates the
252 parent as a class type. This may not be what you want, but is less
255 You could declare a name with subtype such as "Foo!Bar". Moose would
256 accept this allowed, but if you used it in a parameterized type such
257 as "ArrayRef[Foo!Bar]" it wouldn't work. We now do some vetting on
258 names created via the sugar functions, so that they can only contain
259 alphanumerics, ":", and ".".
263 Methods created via an attribute can now fulfill a C<requires>
264 declaration for a role. Honestly we don't know why Stevan didn't make
265 this work originally, he was just insane or something.
267 Stack traces from inlined code will now report the line and file as
268 being in your class, as opposed to in Moose guts.
270 =head1 Version 0.62_02
272 When a class does not provide all of a role's required methods, the
273 error thrown now mentions all of the missing methods, as opposed to
274 just the first missing method.
276 Moose will no longer inline a constructor for your class unless it
277 inherits its constructor from Moose::Object, and will warn when it
278 doesn't inline. If you want to force inlining anyway, pass
279 C<< replace_constructor => 1 >> to C<make_immutable>.
281 If you want to get rid of the warning, pass C<< inline_constructor =>
286 Removed the (deprecated) C<make_immutable> keyword.
288 Removing an attribute from a class now also removes delegation
289 (C<handles>) methods installed for that attribute. This is correct
290 behavior, but if you were wrongly relying on it you might get bit.
294 Roles now add methods by calling C<add_method>, not
295 C<alias_method>. They make sure to always provide a method object,
296 which will be cloned internally. This means that it is now possible to
297 track the source of a method provided by a role, and even follow its
298 history through intermediate roles. This means that methods added by
299 a role now show up when looking at a class's method list/map.
301 Parameter and Union args are now sorted, this makes Int|Str the same
302 constraint as Str|Int. Also, incoming type constraint strings are
303 normalized to remove all whitespace differences. This is mostly for
304 internals and should not affect outside code.
306 L<Moose::Exporter> will no longer remove a subroutine that the
307 exporting package re-exports. Moose re-exports the Carp::confess
308 function, among others. The reasoning is that we cannot know whether
309 you have also explicitly imported those functions for your own use, so
310 we err on the safe side and always keep them.
314 C<Moose::init_meta> should now be called as a method.
316 New modules for extension writers, L<Moose::Exporter> and
317 L<Moose::Util::MetaRole>.
319 =head1 Version 0.55_01
321 Implemented metaclass traits (and wrote a recipe for it):
323 use Moose -traits => 'Foo'
325 This should make writing small Moose extensions a little
330 Fixed C<coerce> to accept anon types just like C<subtype> can.
333 coerce $some_anon_type => from 'Str' => via { ... };
337 Added C<BUILDARGS>, a new step in C<< Moose::Object->new() >>.
341 Fixed how the C<< is => (ro|rw) >> works with custom defined
342 C<reader>, C<writer> and C<accessor> options. See the below table for
345 is => ro, writer => _foo # turns into (reader => foo, writer => _foo)
346 is => rw, writer => _foo # turns into (reader => foo, writer => _foo)
347 is => rw, accessor => _foo # turns into (accessor => _foo)
348 is => ro, accessor => _foo # error, accesor is rw
352 The C<before/around/after> method modifiers now support regexp
353 matching of method names. NOTE: this only works for classes, it is
354 currently not supported in roles, but, ... patches welcome.
356 The C<has> keyword for roles now accepts the same array ref form that
357 L<Moose>.pm does for classes.
359 A trigger on a read-only attribute is no longer an error, as it's
360 useful to trigger off of the constructor.
362 Subtypes of parameterizable types now are parameterizable types
367 Fixed issue where C<DEMOLISHALL> was eating the value in C<$@>, and so
368 not working correctly. It still kind of eats them, but so does vanilla
373 Inherited attributes may now be extended without restriction on the
374 type ('isa', 'does').
376 The entire set of Moose::Meta::TypeConstraint::* classes were
377 refactored in this release. If you were relying on their internals you
378 should test your code carefully.
382 Documenting the use of '+name' with attributes that come from recently
383 composed roles. It makes sense, people are using it, and so why not
384 just officially support it.
386 The C<< Moose::Meta::Class->create >> method now supports roles.
388 It is now possible to make anonymous enum types by passing C<enum> an
389 array reference instead of the C<< enum $name => @values >>.
393 Added the C<make_immutable> keyword as a shortcut to calling
394 C<make_immutable> on the meta object. This eventually got removed!
396 Made C<< init_arg => undef >> work in Moose. This means "do not accept
397 a constructor parameter for this attribute".
399 Type errors now use the provided message. Prior to this release they
404 Moose is now a postmodern object system :)
406 The Role system was completely refactored. It is 100% backwards
407 compat, but the internals were totally changed. If you relied on the
408 internals then you are advised to test carefully.
410 Added method exclusion and aliasing for Roles in this release.
412 Added the L<Moose::Util::TypeConstraints::OptimizedConstraints>
415 Passing a list of values to an accessor (which is only expecting one
416 value) used to be silently ignored, now it throws an error.
420 Added parameterized types and did a pretty heavy refactoring of the
421 type constraint system.
423 Better framework extendability and better support for "making your own
426 =head1 Version 0.25 or before
428 Honestly, you shouldn't be using versions of Moose that are this old,
429 so many bug fixes and speed improvements have been made you would be
430 crazy to not upgrade.
432 Also, I am tired of going through the Changelog so I am stopping here,
433 if anyone would like to continue this please feel free.
437 Stevan Little E<lt>stevan@iinteractive.comE<gt>
439 =head1 COPYRIGHT AND LICENSE
441 Copyright 2009 by Infinity Interactive, Inc.
443 L<http://www.iinteractive.com>
445 This library is free software; you can redistribute it and/or modify
446 it under the same terms as Perl itself.