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 You cannot pass C<< coerce => 1 >> unless the attribute's type constraint has a coercion
25 Previously, this was accepted, and it sort of worked, except that if you
26 attempted to set the attribute after the object was created, you would get a
29 Now you will get an error when you attempt to define the attribute.
31 =item C<no Moose>, C<no Moose::Role>, and C<no Moose::Exporter> no longer unimport strict and warnings
33 This change was made in 1.05, and has now been reverted. We don't know if the
34 user has explicitly loaded strict or warnings outside on their own, and
35 unimporting them is just broken in that case.
37 =item Inversed logic when defining which options can be changed
39 L<Moose::Meta::Attribute> now uses inversed logic when defining which
40 options can be changed. By default all options are allowed to be
41 changed. The previous behaviour required each option to be whitelisted
42 for changing using C<legal_options_for_inheritance> method. This
43 method has been removed. New method C<illegal_options_for_inheritance>
44 can now be used to prevent certain options from being changeable.
46 package Bar::Meta::Attribute;
49 extends 'Moose::Meta::Attribute';
51 has 'my_illegal_option' => (
56 around illegal_options_for_inheritance => sub {
57 return (shift->(@_), qw/my_illegal_option/);
66 =item L<Moose::Object/BUILD> methods are now called when calling C<new_object>
68 Previously, C<BUILD> methods would only be called from C<Moose::Object::new>,
69 but now they are also called when constructing an object via
70 C<Moose::Meta::Class::new_object>. C<BUILD> methods are an inherent part of the
71 object construction process, and this should make C<< $meta->new_object >>
72 actually usable without forcing people to use C<< $meta->name->new >>.
74 =item C<no Moose>, C<no Moose::Role>, and C<no Moose::Exporter> now unimport strict and warnings
76 In the interest of having C<no Moose> clean up everything that C<use Moose>
77 does in the calling scope, C<no Moose> (as well as all other
78 L<Moose::Exporter>-using modules) now unimports strict and warnings.
80 =item Metaclass compatibility checking and fixing should be much more robust
82 The L<metaclass compatibility|Moose/METACLASS COMPATIBILITY AND MOOSE> checking
83 and fixing algorithms have been completely rewritten, in both Class::MOP and
84 Moose. This should resolve many confusing errors when dealing with non-Moose
85 inheritance and with custom metaclasses for things like attributes,
86 constructors, etc. For correct code, the only thing that should require a
87 change is that custom error metaclasses must now inherit from
88 L<Moose::Error::Default>.
96 =item Moose::Meta::TypeConstraint::Class is_subtype_of behavior
98 Earlier versions of L<is_subtype_of|Moose::Meta::TypeConstraint::Class/is_subtype_of>
99 would incorrectly return true when called with itself, its own TC name or
100 its class name as an argument. (i.e. $foo_tc->is_subtype_of('Foo') == 1) This
101 behavior was a caused by C<isa> being checked before the class name. The old
102 behavior can be accessed with L<is_type_of|Moose::Meta::TypeConstraint::Class/is_type_of>
110 =item Moose::Meta::Attribute::Native::Trait::Code no longer creates reader methods by default
112 Earlier versions of L<Moose::Meta::Attribute::Native::Trait::Code> created
113 read-only accessors for the attributes it's been applied to, even if you didn't
114 ask for it with C<< is => 'ro' >>. This incorrect behaviour has now been fixed.
122 =item Moose::Util add_method_modifier behavior
124 add_method_modifier (and subsequently the sugar functions Moose::before,
125 Moose::after, and Moose::around) can now accept arrayrefs, with the same
126 behavior as lists. Types other than arrayref and regexp result in an error.
130 =head1 0.93_01 and 0.94
134 =item Moose::Util::MetaRole API has changed
136 The C<apply_metaclass_roles> function is now called C<apply_metaroles>. The
137 way arguments are supplied has been changed to force you to distinguish
138 between metaroles applied to L<Moose::Meta::Class> (and helpers) versus
139 L<Moose::Meta::Role>.
141 The old API still works, but will warn in a future release, and eventually be
144 =item Moose::Meta::Role has real attributes
146 The attributes returned by L<Moose::Meta::Role> are now instances of the
147 L<Moose::Meta::Role::Attribute> class, instead of bare hash references.
149 =item "no Moose" now removes C<blessed> and C<confess>
151 Moose is now smart enough to know exactly what it exported, even when it
152 re-exports functions from other packages. When you unimport Moose, it will
153 remove these functions from your namespace unless you I<also> imported them
154 directly from their respective packages.
156 If you have a C<no Moose> in your code I<before> you call C<blessed> or
157 C<confess>, your code will break. You can either move the C<no Moose> call
158 later in your code, or explicitly import the relevant functions from the
159 packages that provide them.
161 =item L<Moose::Exporter> is smarter about unimporting re-exports
163 The change above comes from a general improvement to L<Moose::Exporter>. It
164 will now unimport any function it exports, even if that function is a
165 re-export from another package.
167 =item Attributes in roles can no longer override class attributes with "+foo"
169 Previously, this worked more or less accidentally, because role attributes
170 weren't objects. This was never documented, but a few MooseX modules took
173 =item The composition_class_roles attribute in L<Moose::Meta::Role> is now a method
175 This was done to make it possible for roles to alter the the list of
176 composition class roles by applying a method modifiers. Previously, this was
177 an attribute and MooseX modules override it. Since that no longer works, this
180 This I<should> be an attribute, so this may switch back to being an attribute
181 in the future if we can figure out how to make this work.
189 =item Calling $object->new() is no longer deprecated
191 We decided to undeprecate this. Now it just works.
193 =item Both C<get_method_map> and C<get_attribute_map> is deprecated
195 These metaclass methods were never meant to be public, and they are both now
196 deprecated. The work around if you still need the functionality they provided
197 is to iterate over the list of names manually.
199 my %fields = map { $_ => $meta->get_attribute($_) } $meta->get_attribute_list;
201 This was actually a change in L<Class::MOP>, but this version of Moose
202 requires a version of L<Class::MOP> that includes said change.
210 =item Added Native delegation for Code refs
212 See L<Moose::Meta::Attribute::Native::Trait::Code> for details.
214 =item Calling $object->new() is deprecated
216 Moose has long supported this, but it's never really been documented, and we
217 don't think this is a good practice. If you want to construct an object from
218 an existing object, you should provide some sort of alternate constructor like
219 C<< $object->clone >>.
221 Calling C<< $object->new >> now issues a warning, and will be an error in a
224 =item Moose no longer warns if you call C<make_immutable> for a class with mutable ancestors
226 While in theory this is a good thing to warn about, we found so many
227 exceptions to this that doing this properly became quite problematic.
231 =head1 Version 0.89_02
235 =item New Native delegation methods from L<List::Util> and L<List::MoreUtils>
237 In particular, we now have C<reduce>, C<shuffle>, C<uniq>, and C<natatime>.
239 =item The Moose::Exporter with_caller feature is now deprecated
241 Use C<with_meta> instead. The C<with_caller> option will start warning in a
244 =item Moose now warns if you call C<make_immutable> for a class with mutable ancestors
246 This is dangerous because modifying a class after a subclass has been
247 immutabilized will lead to incorrect results in the subclass, due to inlining,
248 caching, etc. This occasionally happens accidentally, when a class loads one
249 of its subclasses in the middle of its class definition, so pointing out that
250 this may cause issues should be helpful. Metaclasses (classes that inherit
251 from L<Class::MOP::Object>) are currently exempt from this check, since at the
252 moment we aren't very consistent about which metaclasses we immutabilize.
254 =item C<enum> and C<duck_type> now take arrayrefs for all forms
256 Previously, calling these functions with a list would take the first element of
257 the list as the type constraint name, and use the remainder as the enum values
258 or method names. This makes the interface inconsistent with the anon-type forms
259 of these functions (which must take an arrayref), and a free-form list where
260 the first value is sometimes special is hard to validate (and harder to give
261 reasonable error messages for). These functions have been changed to take
262 arrayrefs in all their forms - so, C<< enum 'My::Type' => [qw(foo bar)] >> is
263 now the preferred way to create an enum type constraint. The old syntax still
264 works for now, but it will hopefully be deprecated and removed in a future
269 =head1 Version 0.89_01
271 L<Moose::Meta::Attribute::Native> has been moved into the Moose core from
272 L<MooseX::AttributeHelpers>. Major changes include:
276 =item C<traits>, not C<metaclass>
278 Method providers are only available via traits.
280 =item C<handles>, not C<provides> or C<curries>
282 The C<provides> syntax was like core Moose C<< handles => HASHREF >>
283 syntax, but with the keys and values reversed. This was confusing,
284 and AttributeHelpers now uses C<< handles => HASHREF >> in a way that
285 should be intuitive to anyone already familiar with how it is used for
288 The C<curries> functionality provided by AttributeHelpers has been
289 generalized to apply to all cases of C<< handles => HASHREF >>, though
290 not every piece of functionality has been ported (currying with a
291 CODEREF is not supported).
293 =item C<empty> is now C<is_empty>, and means empty, not non-empty
295 Previously, the C<empty> method provided by Arrays and Hashes returned true if
296 the attribute was B<not> empty (no elements). Now it returns true if the
297 attribute B<is> empty. It was also renamed to C<is_empty>, to reflect this.
299 =item C<find> was renamed to C<first>, and C<first> and C<last> were removed
301 L<List::Util> refers to the functionality that we used to provide under C<find>
302 as L<first|List::Util/first>, so that will likely be more familiar (and will
303 fit in better if we decide to add more List::Util functions). C<first> and
304 C<last> were removed, since their functionality is easily duplicated with
307 =item Helpers that take a coderef of one argument now use C<$_>
309 Subroutines passed as the first argument to C<first>, C<map>, and C<grep> now
310 receive their argument in C<$_> rather than as a parameter to the subroutine.
311 Helpers that take a coderef of two or more arguments remain using the argument
312 list (there are technical limitations to using C<$a> and C<$b> like C<sort>
315 See L<Moose::Meta::Attribute::Native> for the new documentation.
319 The C<alias> and C<excludes> role parameters have been renamed to C<-alias>
320 and C<-excludes>. The old names still work, but new code should use the new
321 names, and eventually the old ones will be deprecated and removed.
325 C<< use Moose -metaclass => 'Foo' >> now does alias resolution, just like
326 C<-traits> (and the C<metaclass> and C<traits> options to C<has>).
328 Added two functions C<meta_class_alias> and C<meta_attribute_alias> to
329 L<Moose::Util>, to simplify aliasing metaclasses and metatraits. This is
330 a wrapper around the old
332 package Moose::Meta::Class::Custom::Trait::FooTrait;
333 sub register_implementation { 'My::Meta::Trait' }
339 When an attribute generates I<no> accessors, we now warn. This is to help
340 users who forget the C<is> option. If you really do not want any accessors,
341 you can use C<< is => 'bare' >>. You can maintain back compat with older
342 versions of Moose by using something like:
344 ($Moose::VERSION >= 0.84 ? is => 'bare' : ())
346 When an accessor overwrites an existing method, we now warn. To work around
347 this warning (if you really must have this behavior), you can explicitly
348 remove the method before creating it as an accessor:
352 __PACKAGE__->meta->remove_method('foo');
358 When an unknown option is passed to C<has>, we now warn. You can silence
359 the warning by fixing your code. :)
361 The C<Role> type has been deprecated. On its own, it was useless,
362 since it just checked C<< $object->can('does') >>. If you were using
363 it as a parent type, just call C<role_type('Role::Name')> to create an
364 appropriate type instead.
368 C<use Moose::Exporter;> now imports C<strict> and C<warnings> into packages
373 C<DEMOLISHALL> and C<DEMOLISH> now receive an argument indicating whether or
374 not we are in global destruction.
378 Type constraints no longer run coercions for a value that already matches the
379 constraint. This may affect some (arguably buggy) edge case coercions that
380 rely on side effects in the C<via> clause.
384 L<Moose::Exporter> now accepts the C<-metaclass> option for easily
385 overriding the metaclass (without L<metaclass>). This works for classes
390 Added a C<duck_type> sugar function to L<Moose::Util::TypeConstraints>
391 to make integration with non-Moose classes easier. It simply checks if
392 C<< $obj->can() >> a list of methods.
394 A number of methods (mostly inherited from L<Class::MOP>) have been
395 renamed with a leading underscore to indicate their internal-ness. The
396 old method names will still work for a while, but will warn that the
397 method has been renamed. In a few cases, the method will be removed
398 entirely in the future. This may affect MooseX authors who were using
403 Calling C<subtype> with a name as the only argument now throws an
404 exception. If you want an anonymous subtype do:
406 my $subtype = subtype as 'Foo';
408 This is related to the changes in version 0.71_01.
410 The C<is_needed> method in L<Moose::Meta::Method::Destructor> is now
411 only usable as a class method. Previously, it worked as a class or
412 object method, with a different internal implementation for each
415 The internals of making a class immutable changed a lot in Class::MOP
416 0.78_02, and Moose's internals have changed along with it. The
417 external C<< $metaclass->make_immutable >> method still works the same
422 A mutable class accepted C<< Foo->new(undef) >> without complaint,
423 while an immutable class would blow up with an unhelpful error. Now,
424 in both cases we throw a helpful error instead.
426 This "feature" was originally added to allow for cases such as this:
434 return My::Class->new($args);
436 But we decided this is a bad idea and a little too magical, because it
437 can easily mask real errors.
439 =head1 Version 0.71_01
441 Calling C<type> or C<subtype> without the sugar helpers (C<as>,
442 C<where>, C<message>) is now deprecated.
444 As a side effect, this meant we ended up using Perl prototypes on
445 C<as>, and code like this will no longer work:
447 use Moose::Util::TypeConstraints;
448 use Declare::Constraints::Simple -All;
450 subtype 'ArrayOfInts'
452 => IsArrayRef(IsInt);
454 Instead it must be changed to this:
459 where => IsArrayRef(IsInt)
463 If you want to maintain backwards compat with older versions of Moose,
464 you must explicitly test Moose's C<VERSION>:
466 if ( Moose->VERSION < 0.71_01 ) {
467 subtype 'ArrayOfInts'
469 => IsArrayRef(IsInt);
475 where => IsArrayRef(IsInt)
482 We no longer pass the meta-attribute object as a final argument to
483 triggers. This actually changed for inlined code a while back, but the
484 non-inlined version and the docs were still out of date.
486 If by some chance you actually used this feature, the workaround is
487 simple. You fetch the attribute object from out of the C<$self>
488 that is passed as the first argument to trigger, like so:
494 my ( $self, $value ) = @_;
495 my $attr = $self->meta->find_attribute_by_name('foo');
503 If you created a subtype and passed a parent that Moose didn't know
504 about, it simply ignored the parent. Now it automatically creates the
505 parent as a class type. This may not be what you want, but is less
508 You could declare a name with subtype such as "Foo!Bar". Moose would
509 accept this allowed, but if you used it in a parameterized type such
510 as "ArrayRef[Foo!Bar]" it wouldn't work. We now do some vetting on
511 names created via the sugar functions, so that they can only contain
512 alphanumerics, ":", and ".".
516 Methods created via an attribute can now fulfill a C<requires>
517 declaration for a role. Honestly we don't know why Stevan didn't make
518 this work originally, he was just insane or something.
520 Stack traces from inlined code will now report the line and file as
521 being in your class, as opposed to in Moose guts.
523 =head1 Version 0.62_02
525 When a class does not provide all of a role's required methods, the
526 error thrown now mentions all of the missing methods, as opposed to
527 just the first missing method.
529 Moose will no longer inline a constructor for your class unless it
530 inherits its constructor from Moose::Object, and will warn when it
531 doesn't inline. If you want to force inlining anyway, pass
532 C<< replace_constructor => 1 >> to C<make_immutable>.
534 If you want to get rid of the warning, pass C<< inline_constructor =>
539 Removed the (deprecated) C<make_immutable> keyword.
541 Removing an attribute from a class now also removes delegation
542 (C<handles>) methods installed for that attribute. This is correct
543 behavior, but if you were wrongly relying on it you might get bit.
547 Roles now add methods by calling C<add_method>, not
548 C<alias_method>. They make sure to always provide a method object,
549 which will be cloned internally. This means that it is now possible to
550 track the source of a method provided by a role, and even follow its
551 history through intermediate roles. This means that methods added by
552 a role now show up when looking at a class's method list/map.
554 Parameter and Union args are now sorted, this makes Int|Str the same
555 constraint as Str|Int. Also, incoming type constraint strings are
556 normalized to remove all whitespace differences. This is mostly for
557 internals and should not affect outside code.
559 L<Moose::Exporter> will no longer remove a subroutine that the
560 exporting package re-exports. Moose re-exports the Carp::confess
561 function, among others. The reasoning is that we cannot know whether
562 you have also explicitly imported those functions for your own use, so
563 we err on the safe side and always keep them.
567 C<Moose::init_meta> should now be called as a method.
569 New modules for extension writers, L<Moose::Exporter> and
570 L<Moose::Util::MetaRole>.
572 =head1 Version 0.55_01
574 Implemented metaclass traits (and wrote a recipe for it):
576 use Moose -traits => 'Foo'
578 This should make writing small Moose extensions a little
583 Fixed C<coerce> to accept anon types just like C<subtype> can.
586 coerce $some_anon_type => from 'Str' => via { ... };
590 Added C<BUILDARGS>, a new step in C<< Moose::Object->new() >>.
594 Fixed how the C<< is => (ro|rw) >> works with custom defined
595 C<reader>, C<writer> and C<accessor> options. See the below table for
598 is => ro, writer => _foo # turns into (reader => foo, writer => _foo)
599 is => rw, writer => _foo # turns into (reader => foo, writer => _foo)
600 is => rw, accessor => _foo # turns into (accessor => _foo)
601 is => ro, accessor => _foo # error, accesor is rw
605 The C<before/around/after> method modifiers now support regexp
606 matching of method names. NOTE: this only works for classes, it is
607 currently not supported in roles, but, ... patches welcome.
609 The C<has> keyword for roles now accepts the same array ref form that
610 L<Moose>.pm does for classes.
612 A trigger on a read-only attribute is no longer an error, as it's
613 useful to trigger off of the constructor.
615 Subtypes of parameterizable types now are parameterizable types
620 Fixed issue where C<DEMOLISHALL> was eating the value in C<$@>, and so
621 not working correctly. It still kind of eats them, but so does vanilla
626 Inherited attributes may now be extended without restriction on the
627 type ('isa', 'does').
629 The entire set of Moose::Meta::TypeConstraint::* classes were
630 refactored in this release. If you were relying on their internals you
631 should test your code carefully.
635 Documenting the use of '+name' with attributes that come from recently
636 composed roles. It makes sense, people are using it, and so why not
637 just officially support it.
639 The C<< Moose::Meta::Class->create >> method now supports roles.
641 It is now possible to make anonymous enum types by passing C<enum> an
642 array reference instead of the C<< enum $name => @values >>.
646 Added the C<make_immutable> keyword as a shortcut to calling
647 C<make_immutable> on the meta object. This eventually got removed!
649 Made C<< init_arg => undef >> work in Moose. This means "do not accept
650 a constructor parameter for this attribute".
652 Type errors now use the provided message. Prior to this release they
657 Moose is now a postmodern object system :)
659 The Role system was completely refactored. It is 100% backwards
660 compat, but the internals were totally changed. If you relied on the
661 internals then you are advised to test carefully.
663 Added method exclusion and aliasing for Roles in this release.
665 Added the L<Moose::Util::TypeConstraints::OptimizedConstraints>
668 Passing a list of values to an accessor (which is only expecting one
669 value) used to be silently ignored, now it throws an error.
673 Added parameterized types and did a pretty heavy refactoring of the
674 type constraint system.
676 Better framework extendability and better support for "making your own
679 =head1 Version 0.25 or before
681 Honestly, you shouldn't be using versions of Moose that are this old,
682 so many bug fixes and speed improvements have been made you would be
683 crazy to not upgrade.
685 Also, I am tired of going through the Changelog so I am stopping here,
686 if anyone would like to continue this please feel free.
690 Stevan Little E<lt>stevan@iinteractive.comE<gt>
692 =head1 COPYRIGHT AND LICENSE
694 Copyright 2009 by Infinity Interactive, Inc.
696 L<http://www.iinteractive.com>
698 This library is free software; you can redistribute it and/or modify
699 it under the same terms as Perl itself.