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.
43 =item L<Moose::Object/BUILD> methods are now called when calling C<new_object>
45 Previously, C<BUILD> methods would only be called from C<Moose::Object::new>,
46 but now they are also called when constructing an object via
47 C<Moose::Meta::Class::new_object>. C<BUILD> methods are an inherent part of the
48 object construction process, and this should make C<< $meta->new_object >>
49 actually usable without forcing people to use C<< $meta->name->new >>.
51 =item C<no Moose>, C<no Moose::Role>, and C<no Moose::Exporter> now unimport strict and warnings
53 In the interest of having C<no Moose> clean up everything that C<use Moose>
54 does in the calling scope, C<no Moose> (as well as all other
55 L<Moose::Exporter>-using modules) now unimports strict and warnings.
57 =item Metaclass compatibility checking and fixing should be much more robust
59 The L<metaclass compatibility|Moose/METACLASS COMPATIBILITY AND MOOSE> checking
60 and fixing algorithms have been completely rewritten, in both Class::MOP and
61 Moose. This should resolve many confusing errors when dealing with non-Moose
62 inheritance and with custom metaclasses for things like attributes,
63 constructors, etc. For correct code, the only thing that should require a
64 change is that custom error metaclasses must now inherit from
65 L<Moose::Error::Default>.
73 =item Moose::Meta::TypeConstraint::Class is_subtype_of behavior
75 Earlier versions of L<is_subtype_of|Moose::Meta::TypeConstraint::Class/is_subtype_of>
76 would incorrectly return true when called with itself, its own TC name or
77 its class name as an argument. (i.e. $foo_tc->is_subtype_of('Foo') == 1) This
78 behavior was a caused by C<isa> being checked before the class name. The old
79 behavior can be accessed with L<is_type_of|Moose::Meta::TypeConstraint::Class/is_type_of>
87 =item Moose::Meta::Attribute::Native::Trait::Code no longer creates reader methods by default
89 Earlier versions of L<Moose::Meta::Attribute::Native::Trait::Code> created
90 read-only accessors for the attributes it's been applied to, even if you didn't
91 ask for it with C<< is => 'ro' >>. This incorrect behaviour has now been fixed.
99 =item Moose::Util add_method_modifier behavior
101 add_method_modifier (and subsequently the sugar functions Moose::before,
102 Moose::after, and Moose::around) can now accept arrayrefs, with the same
103 behavior as lists. Types other than arrayref and regexp result in an error.
107 =head1 0.93_01 and 0.94
111 =item Moose::Util::MetaRole API has changed
113 The C<apply_metaclass_roles> function is now called C<apply_metaroles>. The
114 way arguments are supplied has been changed to force you to distinguish
115 between metaroles applied to L<Moose::Meta::Class> (and helpers) versus
116 L<Moose::Meta::Role>.
118 The old API still works, but will warn in a future release, and eventually be
121 =item Moose::Meta::Role has real attributes
123 The attributes returned by L<Moose::Meta::Role> are now instances of the
124 L<Moose::Meta::Role::Attribute> class, instead of bare hash references.
126 =item "no Moose" now removes C<blessed> and C<confess>
128 Moose is now smart enough to know exactly what it exported, even when it
129 re-exports functions from other packages. When you unimport Moose, it will
130 remove these functions from your namespace unless you I<also> imported them
131 directly from their respective packages.
133 If you have a C<no Moose> in your code I<before> you call C<blessed> or
134 C<confess>, your code will break. You can either move the C<no Moose> call
135 later in your code, or explicitly import the relevant functions from the
136 packages that provide them.
138 =item L<Moose::Exporter> is smarter about unimporting re-exports
140 The change above comes from a general improvement to L<Moose::Exporter>. It
141 will now unimport any function it exports, even if that function is a
142 re-export from another package.
144 =item Attributes in roles can no longer override class attributes with "+foo"
146 Previously, this worked more or less accidentally, because role attributes
147 weren't objects. This was never documented, but a few MooseX modules took
150 =item The composition_class_roles attribute in L<Moose::Meta::Role> is now a method
152 This was done to make it possible for roles to alter the the list of
153 composition class roles by applying a method modifiers. Previously, this was
154 an attribute and MooseX modules override it. Since that no longer works, this
157 This I<should> be an attribute, so this may switch back to being an attribute
158 in the future if we can figure out how to make this work.
166 =item Calling $object->new() is no longer deprecated
168 We decided to undeprecate this. Now it just works.
170 =item Both C<get_method_map> and C<get_attribute_map> is deprecated
172 These metaclass methods were never meant to be public, and they are both now
173 deprecated. The work around if you still need the functionality they provided
174 is to iterate over the list of names manually.
176 my %fields = map { $_ => $meta->get_attribute($_) } $meta->get_attribute_list;
178 This was actually a change in L<Class::MOP>, but this version of Moose
179 requires a version of L<Class::MOP> that includes said change.
187 =item Added Native delegation for Code refs
189 See L<Moose::Meta::Attribute::Native::Trait::Code> for details.
191 =item Calling $object->new() is deprecated
193 Moose has long supported this, but it's never really been documented, and we
194 don't think this is a good practice. If you want to construct an object from
195 an existing object, you should provide some sort of alternate constructor like
196 C<< $object->clone >>.
198 Calling C<< $object->new >> now issues a warning, and will be an error in a
201 =item Moose no longer warns if you call C<make_immutable> for a class with mutable ancestors
203 While in theory this is a good thing to warn about, we found so many
204 exceptions to this that doing this properly became quite problematic.
208 =head1 Version 0.89_02
212 =item New Native delegation methods from L<List::Util> and L<List::MoreUtils>
214 In particular, we now have C<reduce>, C<shuffle>, C<uniq>, and C<natatime>.
216 =item The Moose::Exporter with_caller feature is now deprecated
218 Use C<with_meta> instead. The C<with_caller> option will start warning in a
221 =item Moose now warns if you call C<make_immutable> for a class with mutable ancestors
223 This is dangerous because modifying a class after a subclass has been
224 immutabilized will lead to incorrect results in the subclass, due to inlining,
225 caching, etc. This occasionally happens accidentally, when a class loads one
226 of its subclasses in the middle of its class definition, so pointing out that
227 this may cause issues should be helpful. Metaclasses (classes that inherit
228 from L<Class::MOP::Object>) are currently exempt from this check, since at the
229 moment we aren't very consistent about which metaclasses we immutabilize.
231 =item C<enum> and C<duck_type> now take arrayrefs for all forms
233 Previously, calling these functions with a list would take the first element of
234 the list as the type constraint name, and use the remainder as the enum values
235 or method names. This makes the interface inconsistent with the anon-type forms
236 of these functions (which must take an arrayref), and a free-form list where
237 the first value is sometimes special is hard to validate (and harder to give
238 reasonable error messages for). These functions have been changed to take
239 arrayrefs in all their forms - so, C<< enum 'My::Type' => [qw(foo bar)] >> is
240 now the preferred way to create an enum type constraint. The old syntax still
241 works for now, but it will hopefully be deprecated and removed in a future
246 =head1 Version 0.89_01
248 L<Moose::Meta::Attribute::Native> has been moved into the Moose core from
249 L<MooseX::AttributeHelpers>. Major changes include:
253 =item C<traits>, not C<metaclass>
255 Method providers are only available via traits.
257 =item C<handles>, not C<provides> or C<curries>
259 The C<provides> syntax was like core Moose C<< handles => HASHREF >>
260 syntax, but with the keys and values reversed. This was confusing,
261 and AttributeHelpers now uses C<< handles => HASHREF >> in a way that
262 should be intuitive to anyone already familiar with how it is used for
265 The C<curries> functionality provided by AttributeHelpers has been
266 generalized to apply to all cases of C<< handles => HASHREF >>, though
267 not every piece of functionality has been ported (currying with a
268 CODEREF is not supported).
270 =item C<empty> is now C<is_empty>, and means empty, not non-empty
272 Previously, the C<empty> method provided by Arrays and Hashes returned true if
273 the attribute was B<not> empty (no elements). Now it returns true if the
274 attribute B<is> empty. It was also renamed to C<is_empty>, to reflect this.
276 =item C<find> was renamed to C<first>, and C<first> and C<last> were removed
278 L<List::Util> refers to the functionality that we used to provide under C<find>
279 as L<first|List::Util/first>, so that will likely be more familiar (and will
280 fit in better if we decide to add more List::Util functions). C<first> and
281 C<last> were removed, since their functionality is easily duplicated with
284 =item Helpers that take a coderef of one argument now use C<$_>
286 Subroutines passed as the first argument to C<first>, C<map>, and C<grep> now
287 receive their argument in C<$_> rather than as a parameter to the subroutine.
288 Helpers that take a coderef of two or more arguments remain using the argument
289 list (there are technical limitations to using C<$a> and C<$b> like C<sort>
292 See L<Moose::Meta::Attribute::Native> for the new documentation.
296 The C<alias> and C<excludes> role parameters have been renamed to C<-alias>
297 and C<-excludes>. The old names still work, but new code should use the new
298 names, and eventually the old ones will be deprecated and removed.
302 C<< use Moose -metaclass => 'Foo' >> now does alias resolution, just like
303 C<-traits> (and the C<metaclass> and C<traits> options to C<has>).
305 Added two functions C<meta_class_alias> and C<meta_attribute_alias> to
306 L<Moose::Util>, to simplify aliasing metaclasses and metatraits. This is
307 a wrapper around the old
309 package Moose::Meta::Class::Custom::Trait::FooTrait;
310 sub register_implementation { 'My::Meta::Trait' }
316 When an attribute generates I<no> accessors, we now warn. This is to help
317 users who forget the C<is> option. If you really do not want any accessors,
318 you can use C<< is => 'bare' >>. You can maintain back compat with older
319 versions of Moose by using something like:
321 ($Moose::VERSION >= 0.84 ? is => 'bare' : ())
323 When an accessor overwrites an existing method, we now warn. To work around
324 this warning (if you really must have this behavior), you can explicitly
325 remove the method before creating it as an accessor:
329 __PACKAGE__->meta->remove_method('foo');
335 When an unknown option is passed to C<has>, we now warn. You can silence
336 the warning by fixing your code. :)
338 The C<Role> type has been deprecated. On its own, it was useless,
339 since it just checked C<< $object->can('does') >>. If you were using
340 it as a parent type, just call C<role_type('Role::Name')> to create an
341 appropriate type instead.
345 C<use Moose::Exporter;> now imports C<strict> and C<warnings> into packages
350 C<DEMOLISHALL> and C<DEMOLISH> now receive an argument indicating whether or
351 not we are in global destruction.
355 Type constraints no longer run coercions for a value that already matches the
356 constraint. This may affect some (arguably buggy) edge case coercions that
357 rely on side effects in the C<via> clause.
361 L<Moose::Exporter> now accepts the C<-metaclass> option for easily
362 overriding the metaclass (without L<metaclass>). This works for classes
367 Added a C<duck_type> sugar function to L<Moose::Util::TypeConstraints>
368 to make integration with non-Moose classes easier. It simply checks if
369 C<< $obj->can() >> a list of methods.
371 A number of methods (mostly inherited from L<Class::MOP>) have been
372 renamed with a leading underscore to indicate their internal-ness. The
373 old method names will still work for a while, but will warn that the
374 method has been renamed. In a few cases, the method will be removed
375 entirely in the future. This may affect MooseX authors who were using
380 Calling C<subtype> with a name as the only argument now throws an
381 exception. If you want an anonymous subtype do:
383 my $subtype = subtype as 'Foo';
385 This is related to the changes in version 0.71_01.
387 The C<is_needed> method in L<Moose::Meta::Method::Destructor> is now
388 only usable as a class method. Previously, it worked as a class or
389 object method, with a different internal implementation for each
392 The internals of making a class immutable changed a lot in Class::MOP
393 0.78_02, and Moose's internals have changed along with it. The
394 external C<< $metaclass->make_immutable >> method still works the same
399 A mutable class accepted C<< Foo->new(undef) >> without complaint,
400 while an immutable class would blow up with an unhelpful error. Now,
401 in both cases we throw a helpful error instead.
403 This "feature" was originally added to allow for cases such as this:
411 return My::Class->new($args);
413 But we decided this is a bad idea and a little too magical, because it
414 can easily mask real errors.
416 =head1 Version 0.71_01
418 Calling C<type> or C<subtype> without the sugar helpers (C<as>,
419 C<where>, C<message>) is now deprecated.
421 As a side effect, this meant we ended up using Perl prototypes on
422 C<as>, and code like this will no longer work:
424 use Moose::Util::TypeConstraints;
425 use Declare::Constraints::Simple -All;
427 subtype 'ArrayOfInts'
429 => IsArrayRef(IsInt);
431 Instead it must be changed to this:
436 where => IsArrayRef(IsInt)
440 If you want to maintain backwards compat with older versions of Moose,
441 you must explicitly test Moose's C<VERSION>:
443 if ( Moose->VERSION < 0.71_01 ) {
444 subtype 'ArrayOfInts'
446 => IsArrayRef(IsInt);
452 where => IsArrayRef(IsInt)
459 We no longer pass the meta-attribute object as a final argument to
460 triggers. This actually changed for inlined code a while back, but the
461 non-inlined version and the docs were still out of date.
463 If by some chance you actually used this feature, the workaround is
464 simple. You fetch the attribute object from out of the C<$self>
465 that is passed as the first argument to trigger, like so:
471 my ( $self, $value ) = @_;
472 my $attr = $self->meta->find_attribute_by_name('foo');
480 If you created a subtype and passed a parent that Moose didn't know
481 about, it simply ignored the parent. Now it automatically creates the
482 parent as a class type. This may not be what you want, but is less
485 You could declare a name with subtype such as "Foo!Bar". Moose would
486 accept this allowed, but if you used it in a parameterized type such
487 as "ArrayRef[Foo!Bar]" it wouldn't work. We now do some vetting on
488 names created via the sugar functions, so that they can only contain
489 alphanumerics, ":", and ".".
493 Methods created via an attribute can now fulfill a C<requires>
494 declaration for a role. Honestly we don't know why Stevan didn't make
495 this work originally, he was just insane or something.
497 Stack traces from inlined code will now report the line and file as
498 being in your class, as opposed to in Moose guts.
500 =head1 Version 0.62_02
502 When a class does not provide all of a role's required methods, the
503 error thrown now mentions all of the missing methods, as opposed to
504 just the first missing method.
506 Moose will no longer inline a constructor for your class unless it
507 inherits its constructor from Moose::Object, and will warn when it
508 doesn't inline. If you want to force inlining anyway, pass
509 C<< replace_constructor => 1 >> to C<make_immutable>.
511 If you want to get rid of the warning, pass C<< inline_constructor =>
516 Removed the (deprecated) C<make_immutable> keyword.
518 Removing an attribute from a class now also removes delegation
519 (C<handles>) methods installed for that attribute. This is correct
520 behavior, but if you were wrongly relying on it you might get bit.
524 Roles now add methods by calling C<add_method>, not
525 C<alias_method>. They make sure to always provide a method object,
526 which will be cloned internally. This means that it is now possible to
527 track the source of a method provided by a role, and even follow its
528 history through intermediate roles. This means that methods added by
529 a role now show up when looking at a class's method list/map.
531 Parameter and Union args are now sorted, this makes Int|Str the same
532 constraint as Str|Int. Also, incoming type constraint strings are
533 normalized to remove all whitespace differences. This is mostly for
534 internals and should not affect outside code.
536 L<Moose::Exporter> will no longer remove a subroutine that the
537 exporting package re-exports. Moose re-exports the Carp::confess
538 function, among others. The reasoning is that we cannot know whether
539 you have also explicitly imported those functions for your own use, so
540 we err on the safe side and always keep them.
544 C<Moose::init_meta> should now be called as a method.
546 New modules for extension writers, L<Moose::Exporter> and
547 L<Moose::Util::MetaRole>.
549 =head1 Version 0.55_01
551 Implemented metaclass traits (and wrote a recipe for it):
553 use Moose -traits => 'Foo'
555 This should make writing small Moose extensions a little
560 Fixed C<coerce> to accept anon types just like C<subtype> can.
563 coerce $some_anon_type => from 'Str' => via { ... };
567 Added C<BUILDARGS>, a new step in C<< Moose::Object->new() >>.
571 Fixed how the C<< is => (ro|rw) >> works with custom defined
572 C<reader>, C<writer> and C<accessor> options. See the below table for
575 is => ro, writer => _foo # turns into (reader => foo, writer => _foo)
576 is => rw, writer => _foo # turns into (reader => foo, writer => _foo)
577 is => rw, accessor => _foo # turns into (accessor => _foo)
578 is => ro, accessor => _foo # error, accesor is rw
582 The C<before/around/after> method modifiers now support regexp
583 matching of method names. NOTE: this only works for classes, it is
584 currently not supported in roles, but, ... patches welcome.
586 The C<has> keyword for roles now accepts the same array ref form that
587 L<Moose>.pm does for classes.
589 A trigger on a read-only attribute is no longer an error, as it's
590 useful to trigger off of the constructor.
592 Subtypes of parameterizable types now are parameterizable types
597 Fixed issue where C<DEMOLISHALL> was eating the value in C<$@>, and so
598 not working correctly. It still kind of eats them, but so does vanilla
603 Inherited attributes may now be extended without restriction on the
604 type ('isa', 'does').
606 The entire set of Moose::Meta::TypeConstraint::* classes were
607 refactored in this release. If you were relying on their internals you
608 should test your code carefully.
612 Documenting the use of '+name' with attributes that come from recently
613 composed roles. It makes sense, people are using it, and so why not
614 just officially support it.
616 The C<< Moose::Meta::Class->create >> method now supports roles.
618 It is now possible to make anonymous enum types by passing C<enum> an
619 array reference instead of the C<< enum $name => @values >>.
623 Added the C<make_immutable> keyword as a shortcut to calling
624 C<make_immutable> on the meta object. This eventually got removed!
626 Made C<< init_arg => undef >> work in Moose. This means "do not accept
627 a constructor parameter for this attribute".
629 Type errors now use the provided message. Prior to this release they
634 Moose is now a postmodern object system :)
636 The Role system was completely refactored. It is 100% backwards
637 compat, but the internals were totally changed. If you relied on the
638 internals then you are advised to test carefully.
640 Added method exclusion and aliasing for Roles in this release.
642 Added the L<Moose::Util::TypeConstraints::OptimizedConstraints>
645 Passing a list of values to an accessor (which is only expecting one
646 value) used to be silently ignored, now it throws an error.
650 Added parameterized types and did a pretty heavy refactoring of the
651 type constraint system.
653 Better framework extendability and better support for "making your own
656 =head1 Version 0.25 or before
658 Honestly, you shouldn't be using versions of Moose that are this old,
659 so many bug fixes and speed improvements have been made you would be
660 crazy to not upgrade.
662 Also, I am tired of going through the Changelog so I am stopping here,
663 if anyone would like to continue this please feel free.
667 Stevan Little E<lt>stevan@iinteractive.comE<gt>
669 =head1 COPYRIGHT AND LICENSE
671 Copyright 2009 by Infinity Interactive, Inc.
673 L<http://www.iinteractive.com>
675 This library is free software; you can redistribute it and/or modify
676 it under the same terms as Perl itself.