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
23 =item L<Moose::Object/BUILD> methods are now called when calling C<new_object>
25 Previously, C<BUILD> methods would only be called from C<Moose::Object::new>,
26 but now they are also called when constructing an object via
27 C<Moose::Meta::Class::new_object>. C<BUILD> methods are an inherent part of the
28 object construction process, and this should make C<< $meta->new_object >>
29 actually usable without forcing people to use C<< $meta->name->new >>.
31 =item C<no Moose>, C<no Moose::Role>, and C<no Moose::Exporter> now unimport strict and warnings
33 In the interest of having C<no Moose> clean up everything that C<use Moose>
34 does in the calling scope, C<no Moose> (as well as all other
35 L<Moose::Exporter>-using modules) now unimports strict and warnings.
37 =item Metaclass compatibility checking and fixing should be much more robust
39 The L<metaclass compatibility|Moose/METACLASS COMPATIBILITY AND MOOSE> checking
40 and fixing algorithms have been completely rewritten, in both Class::MOP and
41 Moose. This should resolve many confusing errors when dealing with non-Moose
42 inheritance and with custom metaclasses for things like attributes,
43 constructors, etc. For correct code, the only thing that should require a
44 change is that custom error metaclasses must now inherit from
45 L<Moose::Error::Default>.
53 =item Moose::Meta::TypeConstraint::Class is_subtype_of behavior
55 Earlier versions of L<is_subtype_of|Moose::Meta::TypeConstraint::Class/is_subtype_of>
56 would incorrectly return true when called with itself, its own TC name or
57 its class name as an argument. (i.e. $foo_tc->is_subtype_of('Foo') == 1) This
58 behavior was a caused by C<isa> being checked before the class name. The old
59 behavior can be accessed with L<is_type_of|Moose::Meta::TypeConstraint::Class/is_type_of>
67 =item Moose::Meta::Attribute::Native::Trait::Code no longer creates reader methods by default
69 Earlier versions of L<Moose::Meta::Attribute::Native::Trait::Code> created
70 read-only accessors for the attributes it's been applied to, even if you didn't
71 ask for it with C<< is => 'ro' >>. This incorrect behaviour has now been fixed.
79 =item Moose::Util add_method_modifier behavior
81 add_method_modifier (and subsequently the sugar functions Moose::before,
82 Moose::after, and Moose::around) can now accept arrayrefs, with the same
83 behavior as lists. Types other than arrayref and regexp result in an error.
87 =head1 0.93_01 and 0.94
91 =item Moose::Util::MetaRole API has changed
93 The C<apply_metaclass_roles> function is now called C<apply_metaroles>. The
94 way arguments are supplied has been changed to force you to distinguish
95 between metaroles applied to L<Moose::Meta::Class> (and helpers) versus
98 The old API still works, but will warn in a future release, and eventually be
101 =item Moose::Meta::Role has real attributes
103 The attributes returned by L<Moose::Meta::Role> are now instances of the
104 L<Moose::Meta::Role::Attribute> class, instead of bare hash references.
106 =item "no Moose" now removes C<blessed> and C<confess>
108 Moose is now smart enough to know exactly what it exported, even when it
109 re-exports functions from other packages. When you unimport Moose, it will
110 remove these functions from your namespace unless you I<also> imported them
111 directly from their respective packages.
113 If you have a C<no Moose> in your code I<before> you call C<blessed> or
114 C<confess>, your code will break. You can either move the C<no Moose> call
115 later in your code, or explicitly import the relevant functions from the
116 packages that provide them.
118 =item L<Moose::Exporter> is smarter about unimporting re-exports
120 The change above comes from a general improvement to L<Moose::Exporter>. It
121 will now unimport any function it exports, even if that function is a
122 re-export from another package.
124 =item Attributes in roles can no longer override class attributes with "+foo"
126 Previously, this worked more or less accidentally, because role attributes
127 weren't objects. This was never documented, but a few MooseX modules took
130 =item The composition_class_roles attribute in L<Moose::Meta::Role> is now a method
132 This was done to make it possible for roles to alter the the list of
133 composition class roles by applying a method modifiers. Previously, this was
134 an attribute and MooseX modules override it. Since that no longer works, this
137 This I<should> be an attribute, so this may switch back to being an attribute
138 in the future if we can figure out how to make this work.
146 =item Calling $object->new() is no longer deprecated
148 We decided to undeprecate this. Now it just works.
150 =item Both C<get_method_map> and C<get_attribute_map> is deprecated
152 These metaclass methods were never meant to be public, and they are both now
153 deprecated. The work around if you still need the functionality they provided
154 is to iterate over the list of names manually.
156 my %fields = map { $_ => $meta->get_attribute($_) } $meta->get_attribute_list;
158 This was actually a change in L<Class::MOP>, but this version of Moose
159 requires a version of L<Class::MOP> that includes said change.
167 =item Added Native delegation for Code refs
169 See L<Moose::Meta::Attribute::Native::Trait::Code> for details.
171 =item Calling $object->new() is deprecated
173 Moose has long supported this, but it's never really been documented, and we
174 don't think this is a good practice. If you want to construct an object from
175 an existing object, you should provide some sort of alternate constructor like
176 C<< $object->clone >>.
178 Calling C<< $object->new >> now issues a warning, and will be an error in a
181 =item Moose no longer warns if you call C<make_immutable> for a class with mutable ancestors
183 While in theory this is a good thing to warn about, we found so many
184 exceptions to this that doing this properly became quite problematic.
188 =head1 Version 0.89_02
192 =item New Native delegation methods from L<List::Util> and L<List::MoreUtils>
194 In particular, we now have C<reduce>, C<shuffle>, C<uniq>, and C<natatime>.
196 =item The Moose::Exporter with_caller feature is now deprecated
198 Use C<with_meta> instead. The C<with_caller> option will start warning in a
201 =item Moose now warns if you call C<make_immutable> for a class with mutable ancestors
203 This is dangerous because modifying a class after a subclass has been
204 immutabilized will lead to incorrect results in the subclass, due to inlining,
205 caching, etc. This occasionally happens accidentally, when a class loads one
206 of its subclasses in the middle of its class definition, so pointing out that
207 this may cause issues should be helpful. Metaclasses (classes that inherit
208 from L<Class::MOP::Object>) are currently exempt from this check, since at the
209 moment we aren't very consistent about which metaclasses we immutabilize.
211 =item C<enum> and C<duck_type> now take arrayrefs for all forms
213 Previously, calling these functions with a list would take the first element of
214 the list as the type constraint name, and use the remainder as the enum values
215 or method names. This makes the interface inconsistent with the anon-type forms
216 of these functions (which must take an arrayref), and a free-form list where
217 the first value is sometimes special is hard to validate (and harder to give
218 reasonable error messages for). These functions have been changed to take
219 arrayrefs in all their forms - so, C<< enum 'My::Type' => [qw(foo bar)] >> is
220 now the preferred way to create an enum type constraint. The old syntax still
221 works for now, but it will hopefully be deprecated and removed in a future
226 =head1 Version 0.89_01
228 L<Moose::Meta::Attribute::Native> has been moved into the Moose core from
229 L<MooseX::AttributeHelpers>. Major changes include:
233 =item C<traits>, not C<metaclass>
235 Method providers are only available via traits.
237 =item C<handles>, not C<provides> or C<curries>
239 The C<provides> syntax was like core Moose C<< handles => HASHREF >>
240 syntax, but with the keys and values reversed. This was confusing,
241 and AttributeHelpers now uses C<< handles => HASHREF >> in a way that
242 should be intuitive to anyone already familiar with how it is used for
245 The C<curries> functionality provided by AttributeHelpers has been
246 generalized to apply to all cases of C<< handles => HASHREF >>, though
247 not every piece of functionality has been ported (currying with a
248 CODEREF is not supported).
250 =item C<empty> is now C<is_empty>, and means empty, not non-empty
252 Previously, the C<empty> method provided by Arrays and Hashes returned true if
253 the attribute was B<not> empty (no elements). Now it returns true if the
254 attribute B<is> empty. It was also renamed to C<is_empty>, to reflect this.
256 =item C<find> was renamed to C<first>, and C<first> and C<last> were removed
258 L<List::Util> refers to the functionality that we used to provide under C<find>
259 as L<first|List::Util/first>, so that will likely be more familiar (and will
260 fit in better if we decide to add more List::Util functions). C<first> and
261 C<last> were removed, since their functionality is easily duplicated with
264 =item Helpers that take a coderef of one argument now use C<$_>
266 Subroutines passed as the first argument to C<first>, C<map>, and C<grep> now
267 receive their argument in C<$_> rather than as a parameter to the subroutine.
268 Helpers that take a coderef of two or more arguments remain using the argument
269 list (there are technical limitations to using C<$a> and C<$b> like C<sort>
272 See L<Moose::Meta::Attribute::Native> for the new documentation.
276 The C<alias> and C<excludes> role parameters have been renamed to C<-alias>
277 and C<-excludes>. The old names still work, but new code should use the new
278 names, and eventually the old ones will be deprecated and removed.
282 C<< use Moose -metaclass => 'Foo' >> now does alias resolution, just like
283 C<-traits> (and the C<metaclass> and C<traits> options to C<has>).
285 Added two functions C<meta_class_alias> and C<meta_attribute_alias> to
286 L<Moose::Util>, to simplify aliasing metaclasses and metatraits. This is
287 a wrapper around the old
289 package Moose::Meta::Class::Custom::Trait::FooTrait;
290 sub register_implementation { 'My::Meta::Trait' }
296 When an attribute generates I<no> accessors, we now warn. This is to help
297 users who forget the C<is> option. If you really do not want any accessors,
298 you can use C<< is => 'bare' >>. You can maintain back compat with older
299 versions of Moose by using something like:
301 ($Moose::VERSION >= 0.84 ? is => 'bare' : ())
303 When an accessor overwrites an existing method, we now warn. To work around
304 this warning (if you really must have this behavior), you can explicitly
305 remove the method before creating it as an accessor:
309 __PACKAGE__->meta->remove_method('foo');
315 When an unknown option is passed to C<has>, we now warn. You can silence
316 the warning by fixing your code. :)
318 The C<Role> type has been deprecated. On its own, it was useless,
319 since it just checked C<< $object->can('does') >>. If you were using
320 it as a parent type, just call C<role_type('Role::Name')> to create an
321 appropriate type instead.
325 C<use Moose::Exporter;> now imports C<strict> and C<warnings> into packages
330 C<DEMOLISHALL> and C<DEMOLISH> now receive an argument indicating whether or
331 not we are in global destruction.
335 Type constraints no longer run coercions for a value that already matches the
336 constraint. This may affect some (arguably buggy) edge case coercions that
337 rely on side effects in the C<via> clause.
341 L<Moose::Exporter> now accepts the C<-metaclass> option for easily
342 overriding the metaclass (without L<metaclass>). This works for classes
347 Added a C<duck_type> sugar function to L<Moose::Util::TypeConstraints>
348 to make integration with non-Moose classes easier. It simply checks if
349 C<< $obj->can() >> a list of methods.
351 A number of methods (mostly inherited from L<Class::MOP>) have been
352 renamed with a leading underscore to indicate their internal-ness. The
353 old method names will still work for a while, but will warn that the
354 method has been renamed. In a few cases, the method will be removed
355 entirely in the future. This may affect MooseX authors who were using
360 Calling C<subtype> with a name as the only argument now throws an
361 exception. If you want an anonymous subtype do:
363 my $subtype = subtype as 'Foo';
365 This is related to the changes in version 0.71_01.
367 The C<is_needed> method in L<Moose::Meta::Method::Destructor> is now
368 only usable as a class method. Previously, it worked as a class or
369 object method, with a different internal implementation for each
372 The internals of making a class immutable changed a lot in Class::MOP
373 0.78_02, and Moose's internals have changed along with it. The
374 external C<< $metaclass->make_immutable >> method still works the same
379 A mutable class accepted C<< Foo->new(undef) >> without complaint,
380 while an immutable class would blow up with an unhelpful error. Now,
381 in both cases we throw a helpful error instead.
383 This "feature" was originally added to allow for cases such as this:
391 return My::Class->new($args);
393 But we decided this is a bad idea and a little too magical, because it
394 can easily mask real errors.
396 =head1 Version 0.71_01
398 Calling C<type> or C<subtype> without the sugar helpers (C<as>,
399 C<where>, C<message>) is now deprecated.
401 As a side effect, this meant we ended up using Perl prototypes on
402 C<as>, and code like this will no longer work:
404 use Moose::Util::TypeConstraints;
405 use Declare::Constraints::Simple -All;
407 subtype 'ArrayOfInts'
409 => IsArrayRef(IsInt);
411 Instead it must be changed to this:
416 where => IsArrayRef(IsInt)
420 If you want to maintain backwards compat with older versions of Moose,
421 you must explicitly test Moose's C<VERSION>:
423 if ( Moose->VERSION < 0.71_01 ) {
424 subtype 'ArrayOfInts'
426 => IsArrayRef(IsInt);
432 where => IsArrayRef(IsInt)
439 We no longer pass the meta-attribute object as a final argument to
440 triggers. This actually changed for inlined code a while back, but the
441 non-inlined version and the docs were still out of date.
443 If by some chance you actually used this feature, the workaround is
444 simple. You fetch the attribute object from out of the C<$self>
445 that is passed as the first argument to trigger, like so:
451 my ( $self, $value ) = @_;
452 my $attr = $self->meta->find_attribute_by_name('foo');
460 If you created a subtype and passed a parent that Moose didn't know
461 about, it simply ignored the parent. Now it automatically creates the
462 parent as a class type. This may not be what you want, but is less
465 You could declare a name with subtype such as "Foo!Bar". Moose would
466 accept this allowed, but if you used it in a parameterized type such
467 as "ArrayRef[Foo!Bar]" it wouldn't work. We now do some vetting on
468 names created via the sugar functions, so that they can only contain
469 alphanumerics, ":", and ".".
473 Methods created via an attribute can now fulfill a C<requires>
474 declaration for a role. Honestly we don't know why Stevan didn't make
475 this work originally, he was just insane or something.
477 Stack traces from inlined code will now report the line and file as
478 being in your class, as opposed to in Moose guts.
480 =head1 Version 0.62_02
482 When a class does not provide all of a role's required methods, the
483 error thrown now mentions all of the missing methods, as opposed to
484 just the first missing method.
486 Moose will no longer inline a constructor for your class unless it
487 inherits its constructor from Moose::Object, and will warn when it
488 doesn't inline. If you want to force inlining anyway, pass
489 C<< replace_constructor => 1 >> to C<make_immutable>.
491 If you want to get rid of the warning, pass C<< inline_constructor =>
496 Removed the (deprecated) C<make_immutable> keyword.
498 Removing an attribute from a class now also removes delegation
499 (C<handles>) methods installed for that attribute. This is correct
500 behavior, but if you were wrongly relying on it you might get bit.
504 Roles now add methods by calling C<add_method>, not
505 C<alias_method>. They make sure to always provide a method object,
506 which will be cloned internally. This means that it is now possible to
507 track the source of a method provided by a role, and even follow its
508 history through intermediate roles. This means that methods added by
509 a role now show up when looking at a class's method list/map.
511 Parameter and Union args are now sorted, this makes Int|Str the same
512 constraint as Str|Int. Also, incoming type constraint strings are
513 normalized to remove all whitespace differences. This is mostly for
514 internals and should not affect outside code.
516 L<Moose::Exporter> will no longer remove a subroutine that the
517 exporting package re-exports. Moose re-exports the Carp::confess
518 function, among others. The reasoning is that we cannot know whether
519 you have also explicitly imported those functions for your own use, so
520 we err on the safe side and always keep them.
524 C<Moose::init_meta> should now be called as a method.
526 New modules for extension writers, L<Moose::Exporter> and
527 L<Moose::Util::MetaRole>.
529 =head1 Version 0.55_01
531 Implemented metaclass traits (and wrote a recipe for it):
533 use Moose -traits => 'Foo'
535 This should make writing small Moose extensions a little
540 Fixed C<coerce> to accept anon types just like C<subtype> can.
543 coerce $some_anon_type => from 'Str' => via { ... };
547 Added C<BUILDARGS>, a new step in C<< Moose::Object->new() >>.
551 Fixed how the C<< is => (ro|rw) >> works with custom defined
552 C<reader>, C<writer> and C<accessor> options. See the below table for
555 is => ro, writer => _foo # turns into (reader => foo, writer => _foo)
556 is => rw, writer => _foo # turns into (reader => foo, writer => _foo)
557 is => rw, accessor => _foo # turns into (accessor => _foo)
558 is => ro, accessor => _foo # error, accesor is rw
562 The C<before/around/after> method modifiers now support regexp
563 matching of method names. NOTE: this only works for classes, it is
564 currently not supported in roles, but, ... patches welcome.
566 The C<has> keyword for roles now accepts the same array ref form that
567 L<Moose>.pm does for classes.
569 A trigger on a read-only attribute is no longer an error, as it's
570 useful to trigger off of the constructor.
572 Subtypes of parameterizable types now are parameterizable types
577 Fixed issue where C<DEMOLISHALL> was eating the value in C<$@>, and so
578 not working correctly. It still kind of eats them, but so does vanilla
583 Inherited attributes may now be extended without restriction on the
584 type ('isa', 'does').
586 The entire set of Moose::Meta::TypeConstraint::* classes were
587 refactored in this release. If you were relying on their internals you
588 should test your code carefully.
592 Documenting the use of '+name' with attributes that come from recently
593 composed roles. It makes sense, people are using it, and so why not
594 just officially support it.
596 The C<< Moose::Meta::Class->create >> method now supports roles.
598 It is now possible to make anonymous enum types by passing C<enum> an
599 array reference instead of the C<< enum $name => @values >>.
603 Added the C<make_immutable> keyword as a shortcut to calling
604 C<make_immutable> on the meta object. This eventually got removed!
606 Made C<< init_arg => undef >> work in Moose. This means "do not accept
607 a constructor parameter for this attribute".
609 Type errors now use the provided message. Prior to this release they
614 Moose is now a postmodern object system :)
616 The Role system was completely refactored. It is 100% backwards
617 compat, but the internals were totally changed. If you relied on the
618 internals then you are advised to test carefully.
620 Added method exclusion and aliasing for Roles in this release.
622 Added the L<Moose::Util::TypeConstraints::OptimizedConstraints>
625 Passing a list of values to an accessor (which is only expecting one
626 value) used to be silently ignored, now it throws an error.
630 Added parameterized types and did a pretty heavy refactoring of the
631 type constraint system.
633 Better framework extendability and better support for "making your own
636 =head1 Version 0.25 or before
638 Honestly, you shouldn't be using versions of Moose that are this old,
639 so many bug fixes and speed improvements have been made you would be
640 crazy to not upgrade.
642 Also, I am tired of going through the Changelog so I am stopping here,
643 if anyone would like to continue this please feel free.
647 Stevan Little E<lt>stevan@iinteractive.comE<gt>
649 =head1 COPYRIGHT AND LICENSE
651 Copyright 2009 by Infinity Interactive, Inc.
653 L<http://www.iinteractive.com>
655 This library is free software; you can redistribute it and/or modify
656 it under the same terms as Perl itself.