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 Reversed logic when defining which options can be changed
39 L<Moose::Meta::Attribute> now uses reversed 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 This also now only throws an error if the illegal option was actually
47 changed. If the superclass version of an attribute didn't specify this
48 option at all, the subclass version can still add it as an option.
50 Example of overriding this in an attribute trait:
52 package Bar::Meta::Attribute;
55 has 'my_illegal_option' => (
60 around illegal_options_for_inheritance => sub {
61 return (shift->(@_), qw/my_illegal_option/);
70 =item L<Moose::Object/BUILD> methods are now called when calling C<new_object>
72 Previously, C<BUILD> methods would only be called from C<Moose::Object::new>,
73 but now they are also called when constructing an object via
74 C<Moose::Meta::Class::new_object>. C<BUILD> methods are an inherent part of the
75 object construction process, and this should make C<< $meta->new_object >>
76 actually usable without forcing people to use C<< $meta->name->new >>.
78 =item C<no Moose>, C<no Moose::Role>, and C<no Moose::Exporter> now unimport strict and warnings
80 In the interest of having C<no Moose> clean up everything that C<use Moose>
81 does in the calling scope, C<no Moose> (as well as all other
82 L<Moose::Exporter>-using modules) now unimports strict and warnings.
84 =item Metaclass compatibility checking and fixing should be much more robust
86 The L<metaclass compatibility|Moose/METACLASS COMPATIBILITY AND MOOSE> checking
87 and fixing algorithms have been completely rewritten, in both Class::MOP and
88 Moose. This should resolve many confusing errors when dealing with non-Moose
89 inheritance and with custom metaclasses for things like attributes,
90 constructors, etc. For correct code, the only thing that should require a
91 change is that custom error metaclasses must now inherit from
92 L<Moose::Error::Default>.
100 =item Moose::Meta::TypeConstraint::Class is_subtype_of behavior
102 Earlier versions of L<is_subtype_of|Moose::Meta::TypeConstraint::Class/is_subtype_of>
103 would incorrectly return true when called with itself, its own TC name or
104 its class name as an argument. (i.e. $foo_tc->is_subtype_of('Foo') == 1) This
105 behavior was a caused by C<isa> being checked before the class name. The old
106 behavior can be accessed with L<is_type_of|Moose::Meta::TypeConstraint::Class/is_type_of>
114 =item Moose::Meta::Attribute::Native::Trait::Code no longer creates reader methods by default
116 Earlier versions of L<Moose::Meta::Attribute::Native::Trait::Code> created
117 read-only accessors for the attributes it's been applied to, even if you didn't
118 ask for it with C<< is => 'ro' >>. This incorrect behaviour has now been fixed.
126 =item Moose::Util add_method_modifier behavior
128 add_method_modifier (and subsequently the sugar functions Moose::before,
129 Moose::after, and Moose::around) can now accept arrayrefs, with the same
130 behavior as lists. Types other than arrayref and regexp result in an error.
134 =head1 0.93_01 and 0.94
138 =item Moose::Util::MetaRole API has changed
140 The C<apply_metaclass_roles> function is now called C<apply_metaroles>. The
141 way arguments are supplied has been changed to force you to distinguish
142 between metaroles applied to L<Moose::Meta::Class> (and helpers) versus
143 L<Moose::Meta::Role>.
145 The old API still works, but will warn in a future release, and eventually be
148 =item Moose::Meta::Role has real attributes
150 The attributes returned by L<Moose::Meta::Role> are now instances of the
151 L<Moose::Meta::Role::Attribute> class, instead of bare hash references.
153 =item "no Moose" now removes C<blessed> and C<confess>
155 Moose is now smart enough to know exactly what it exported, even when it
156 re-exports functions from other packages. When you unimport Moose, it will
157 remove these functions from your namespace unless you I<also> imported them
158 directly from their respective packages.
160 If you have a C<no Moose> in your code I<before> you call C<blessed> or
161 C<confess>, your code will break. You can either move the C<no Moose> call
162 later in your code, or explicitly import the relevant functions from the
163 packages that provide them.
165 =item L<Moose::Exporter> is smarter about unimporting re-exports
167 The change above comes from a general improvement to L<Moose::Exporter>. It
168 will now unimport any function it exports, even if that function is a
169 re-export from another package.
171 =item Attributes in roles can no longer override class attributes with "+foo"
173 Previously, this worked more or less accidentally, because role attributes
174 weren't objects. This was never documented, but a few MooseX modules took
177 =item The composition_class_roles attribute in L<Moose::Meta::Role> is now a method
179 This was done to make it possible for roles to alter the the list of
180 composition class roles by applying a method modifiers. Previously, this was
181 an attribute and MooseX modules override it. Since that no longer works, this
184 This I<should> be an attribute, so this may switch back to being an attribute
185 in the future if we can figure out how to make this work.
193 =item Calling $object->new() is no longer deprecated
195 We decided to undeprecate this. Now it just works.
197 =item Both C<get_method_map> and C<get_attribute_map> is deprecated
199 These metaclass methods were never meant to be public, and they are both now
200 deprecated. The work around if you still need the functionality they provided
201 is to iterate over the list of names manually.
203 my %fields = map { $_ => $meta->get_attribute($_) } $meta->get_attribute_list;
205 This was actually a change in L<Class::MOP>, but this version of Moose
206 requires a version of L<Class::MOP> that includes said change.
214 =item Added Native delegation for Code refs
216 See L<Moose::Meta::Attribute::Native::Trait::Code> for details.
218 =item Calling $object->new() is deprecated
220 Moose has long supported this, but it's never really been documented, and we
221 don't think this is a good practice. If you want to construct an object from
222 an existing object, you should provide some sort of alternate constructor like
223 C<< $object->clone >>.
225 Calling C<< $object->new >> now issues a warning, and will be an error in a
228 =item Moose no longer warns if you call C<make_immutable> for a class with mutable ancestors
230 While in theory this is a good thing to warn about, we found so many
231 exceptions to this that doing this properly became quite problematic.
235 =head1 Version 0.89_02
239 =item New Native delegation methods from L<List::Util> and L<List::MoreUtils>
241 In particular, we now have C<reduce>, C<shuffle>, C<uniq>, and C<natatime>.
243 =item The Moose::Exporter with_caller feature is now deprecated
245 Use C<with_meta> instead. The C<with_caller> option will start warning in a
248 =item Moose now warns if you call C<make_immutable> for a class with mutable ancestors
250 This is dangerous because modifying a class after a subclass has been
251 immutabilized will lead to incorrect results in the subclass, due to inlining,
252 caching, etc. This occasionally happens accidentally, when a class loads one
253 of its subclasses in the middle of its class definition, so pointing out that
254 this may cause issues should be helpful. Metaclasses (classes that inherit
255 from L<Class::MOP::Object>) are currently exempt from this check, since at the
256 moment we aren't very consistent about which metaclasses we immutabilize.
258 =item C<enum> and C<duck_type> now take arrayrefs for all forms
260 Previously, calling these functions with a list would take the first element of
261 the list as the type constraint name, and use the remainder as the enum values
262 or method names. This makes the interface inconsistent with the anon-type forms
263 of these functions (which must take an arrayref), and a free-form list where
264 the first value is sometimes special is hard to validate (and harder to give
265 reasonable error messages for). These functions have been changed to take
266 arrayrefs in all their forms - so, C<< enum 'My::Type' => [qw(foo bar)] >> is
267 now the preferred way to create an enum type constraint. The old syntax still
268 works for now, but it will hopefully be deprecated and removed in a future
273 =head1 Version 0.89_01
275 L<Moose::Meta::Attribute::Native> has been moved into the Moose core from
276 L<MooseX::AttributeHelpers>. Major changes include:
280 =item C<traits>, not C<metaclass>
282 Method providers are only available via traits.
284 =item C<handles>, not C<provides> or C<curries>
286 The C<provides> syntax was like core Moose C<< handles => HASHREF >>
287 syntax, but with the keys and values reversed. This was confusing,
288 and AttributeHelpers now uses C<< handles => HASHREF >> in a way that
289 should be intuitive to anyone already familiar with how it is used for
292 The C<curries> functionality provided by AttributeHelpers has been
293 generalized to apply to all cases of C<< handles => HASHREF >>, though
294 not every piece of functionality has been ported (currying with a
295 CODEREF is not supported).
297 =item C<empty> is now C<is_empty>, and means empty, not non-empty
299 Previously, the C<empty> method provided by Arrays and Hashes returned true if
300 the attribute was B<not> empty (no elements). Now it returns true if the
301 attribute B<is> empty. It was also renamed to C<is_empty>, to reflect this.
303 =item C<find> was renamed to C<first>, and C<first> and C<last> were removed
305 L<List::Util> refers to the functionality that we used to provide under C<find>
306 as L<first|List::Util/first>, so that will likely be more familiar (and will
307 fit in better if we decide to add more List::Util functions). C<first> and
308 C<last> were removed, since their functionality is easily duplicated with
311 =item Helpers that take a coderef of one argument now use C<$_>
313 Subroutines passed as the first argument to C<first>, C<map>, and C<grep> now
314 receive their argument in C<$_> rather than as a parameter to the subroutine.
315 Helpers that take a coderef of two or more arguments remain using the argument
316 list (there are technical limitations to using C<$a> and C<$b> like C<sort>
319 See L<Moose::Meta::Attribute::Native> for the new documentation.
323 The C<alias> and C<excludes> role parameters have been renamed to C<-alias>
324 and C<-excludes>. The old names still work, but new code should use the new
325 names, and eventually the old ones will be deprecated and removed.
329 C<< use Moose -metaclass => 'Foo' >> now does alias resolution, just like
330 C<-traits> (and the C<metaclass> and C<traits> options to C<has>).
332 Added two functions C<meta_class_alias> and C<meta_attribute_alias> to
333 L<Moose::Util>, to simplify aliasing metaclasses and metatraits. This is
334 a wrapper around the old
336 package Moose::Meta::Class::Custom::Trait::FooTrait;
337 sub register_implementation { 'My::Meta::Trait' }
343 When an attribute generates I<no> accessors, we now warn. This is to help
344 users who forget the C<is> option. If you really do not want any accessors,
345 you can use C<< is => 'bare' >>. You can maintain back compat with older
346 versions of Moose by using something like:
348 ($Moose::VERSION >= 0.84 ? is => 'bare' : ())
350 When an accessor overwrites an existing method, we now warn. To work around
351 this warning (if you really must have this behavior), you can explicitly
352 remove the method before creating it as an accessor:
356 __PACKAGE__->meta->remove_method('foo');
362 When an unknown option is passed to C<has>, we now warn. You can silence
363 the warning by fixing your code. :)
365 The C<Role> type has been deprecated. On its own, it was useless,
366 since it just checked C<< $object->can('does') >>. If you were using
367 it as a parent type, just call C<role_type('Role::Name')> to create an
368 appropriate type instead.
372 C<use Moose::Exporter;> now imports C<strict> and C<warnings> into packages
377 C<DEMOLISHALL> and C<DEMOLISH> now receive an argument indicating whether or
378 not we are in global destruction.
382 Type constraints no longer run coercions for a value that already matches the
383 constraint. This may affect some (arguably buggy) edge case coercions that
384 rely on side effects in the C<via> clause.
388 L<Moose::Exporter> now accepts the C<-metaclass> option for easily
389 overriding the metaclass (without L<metaclass>). This works for classes
394 Added a C<duck_type> sugar function to L<Moose::Util::TypeConstraints>
395 to make integration with non-Moose classes easier. It simply checks if
396 C<< $obj->can() >> a list of methods.
398 A number of methods (mostly inherited from L<Class::MOP>) have been
399 renamed with a leading underscore to indicate their internal-ness. The
400 old method names will still work for a while, but will warn that the
401 method has been renamed. In a few cases, the method will be removed
402 entirely in the future. This may affect MooseX authors who were using
407 Calling C<subtype> with a name as the only argument now throws an
408 exception. If you want an anonymous subtype do:
410 my $subtype = subtype as 'Foo';
412 This is related to the changes in version 0.71_01.
414 The C<is_needed> method in L<Moose::Meta::Method::Destructor> is now
415 only usable as a class method. Previously, it worked as a class or
416 object method, with a different internal implementation for each
419 The internals of making a class immutable changed a lot in Class::MOP
420 0.78_02, and Moose's internals have changed along with it. The
421 external C<< $metaclass->make_immutable >> method still works the same
426 A mutable class accepted C<< Foo->new(undef) >> without complaint,
427 while an immutable class would blow up with an unhelpful error. Now,
428 in both cases we throw a helpful error instead.
430 This "feature" was originally added to allow for cases such as this:
438 return My::Class->new($args);
440 But we decided this is a bad idea and a little too magical, because it
441 can easily mask real errors.
443 =head1 Version 0.71_01
445 Calling C<type> or C<subtype> without the sugar helpers (C<as>,
446 C<where>, C<message>) is now deprecated.
448 As a side effect, this meant we ended up using Perl prototypes on
449 C<as>, and code like this will no longer work:
451 use Moose::Util::TypeConstraints;
452 use Declare::Constraints::Simple -All;
454 subtype 'ArrayOfInts'
456 => IsArrayRef(IsInt);
458 Instead it must be changed to this:
463 where => IsArrayRef(IsInt)
467 If you want to maintain backwards compat with older versions of Moose,
468 you must explicitly test Moose's C<VERSION>:
470 if ( Moose->VERSION < 0.71_01 ) {
471 subtype 'ArrayOfInts'
473 => IsArrayRef(IsInt);
479 where => IsArrayRef(IsInt)
486 We no longer pass the meta-attribute object as a final argument to
487 triggers. This actually changed for inlined code a while back, but the
488 non-inlined version and the docs were still out of date.
490 If by some chance you actually used this feature, the workaround is
491 simple. You fetch the attribute object from out of the C<$self>
492 that is passed as the first argument to trigger, like so:
498 my ( $self, $value ) = @_;
499 my $attr = $self->meta->find_attribute_by_name('foo');
507 If you created a subtype and passed a parent that Moose didn't know
508 about, it simply ignored the parent. Now it automatically creates the
509 parent as a class type. This may not be what you want, but is less
512 You could declare a name with subtype such as "Foo!Bar". Moose would
513 accept this allowed, but if you used it in a parameterized type such
514 as "ArrayRef[Foo!Bar]" it wouldn't work. We now do some vetting on
515 names created via the sugar functions, so that they can only contain
516 alphanumerics, ":", and ".".
520 Methods created via an attribute can now fulfill a C<requires>
521 declaration for a role. Honestly we don't know why Stevan didn't make
522 this work originally, he was just insane or something.
524 Stack traces from inlined code will now report the line and file as
525 being in your class, as opposed to in Moose guts.
527 =head1 Version 0.62_02
529 When a class does not provide all of a role's required methods, the
530 error thrown now mentions all of the missing methods, as opposed to
531 just the first missing method.
533 Moose will no longer inline a constructor for your class unless it
534 inherits its constructor from Moose::Object, and will warn when it
535 doesn't inline. If you want to force inlining anyway, pass
536 C<< replace_constructor => 1 >> to C<make_immutable>.
538 If you want to get rid of the warning, pass C<< inline_constructor =>
543 Removed the (deprecated) C<make_immutable> keyword.
545 Removing an attribute from a class now also removes delegation
546 (C<handles>) methods installed for that attribute. This is correct
547 behavior, but if you were wrongly relying on it you might get bit.
551 Roles now add methods by calling C<add_method>, not
552 C<alias_method>. They make sure to always provide a method object,
553 which will be cloned internally. This means that it is now possible to
554 track the source of a method provided by a role, and even follow its
555 history through intermediate roles. This means that methods added by
556 a role now show up when looking at a class's method list/map.
558 Parameter and Union args are now sorted, this makes Int|Str the same
559 constraint as Str|Int. Also, incoming type constraint strings are
560 normalized to remove all whitespace differences. This is mostly for
561 internals and should not affect outside code.
563 L<Moose::Exporter> will no longer remove a subroutine that the
564 exporting package re-exports. Moose re-exports the Carp::confess
565 function, among others. The reasoning is that we cannot know whether
566 you have also explicitly imported those functions for your own use, so
567 we err on the safe side and always keep them.
571 C<Moose::init_meta> should now be called as a method.
573 New modules for extension writers, L<Moose::Exporter> and
574 L<Moose::Util::MetaRole>.
576 =head1 Version 0.55_01
578 Implemented metaclass traits (and wrote a recipe for it):
580 use Moose -traits => 'Foo'
582 This should make writing small Moose extensions a little
587 Fixed C<coerce> to accept anon types just like C<subtype> can.
590 coerce $some_anon_type => from 'Str' => via { ... };
594 Added C<BUILDARGS>, a new step in C<< Moose::Object->new() >>.
598 Fixed how the C<< is => (ro|rw) >> works with custom defined
599 C<reader>, C<writer> and C<accessor> options. See the below table for
602 is => ro, writer => _foo # turns into (reader => foo, writer => _foo)
603 is => rw, writer => _foo # turns into (reader => foo, writer => _foo)
604 is => rw, accessor => _foo # turns into (accessor => _foo)
605 is => ro, accessor => _foo # error, accesor is rw
609 The C<before/around/after> method modifiers now support regexp
610 matching of method names. NOTE: this only works for classes, it is
611 currently not supported in roles, but, ... patches welcome.
613 The C<has> keyword for roles now accepts the same array ref form that
614 L<Moose>.pm does for classes.
616 A trigger on a read-only attribute is no longer an error, as it's
617 useful to trigger off of the constructor.
619 Subtypes of parameterizable types now are parameterizable types
624 Fixed issue where C<DEMOLISHALL> was eating the value in C<$@>, and so
625 not working correctly. It still kind of eats them, but so does vanilla
630 Inherited attributes may now be extended without restriction on the
631 type ('isa', 'does').
633 The entire set of Moose::Meta::TypeConstraint::* classes were
634 refactored in this release. If you were relying on their internals you
635 should test your code carefully.
639 Documenting the use of '+name' with attributes that come from recently
640 composed roles. It makes sense, people are using it, and so why not
641 just officially support it.
643 The C<< Moose::Meta::Class->create >> method now supports roles.
645 It is now possible to make anonymous enum types by passing C<enum> an
646 array reference instead of the C<< enum $name => @values >>.
650 Added the C<make_immutable> keyword as a shortcut to calling
651 C<make_immutable> on the meta object. This eventually got removed!
653 Made C<< init_arg => undef >> work in Moose. This means "do not accept
654 a constructor parameter for this attribute".
656 Type errors now use the provided message. Prior to this release they
661 Moose is now a postmodern object system :)
663 The Role system was completely refactored. It is 100% backwards
664 compat, but the internals were totally changed. If you relied on the
665 internals then you are advised to test carefully.
667 Added method exclusion and aliasing for Roles in this release.
669 Added the L<Moose::Util::TypeConstraints::OptimizedConstraints>
672 Passing a list of values to an accessor (which is only expecting one
673 value) used to be silently ignored, now it throws an error.
677 Added parameterized types and did a pretty heavy refactoring of the
678 type constraint system.
680 Better framework extendability and better support for "making your own
683 =head1 Version 0.25 or before
685 Honestly, you shouldn't be using versions of Moose that are this old,
686 so many bug fixes and speed improvements have been made you would be
687 crazy to not upgrade.
689 Also, I am tired of going through the Changelog so I am stopping here,
690 if anyone would like to continue this please feel free.
694 Stevan Little E<lt>stevan@iinteractive.comE<gt>
696 =head1 COPYRIGHT AND LICENSE
698 Copyright 2009 by Infinity Interactive, Inc.
700 L<http://www.iinteractive.com>
702 This library is free software; you can redistribute it and/or modify
703 it under the same terms as Perl itself.