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 All deprecated features now warn
25 Previously, deprecation mostly consisted of simply saying "X is deprecated" in
26 the Changes file. We were not very consistent about actually warning. Now, all
27 deprecated features still present in Moose actually give a warning. The
28 warning is issued once per calling package. See L<Moose::Deprecated> for more
31 =item You cannot pass C<< coerce => 1 >> unless the attribute's type constraint has a coercion
33 Previously, this was accepted, and it sort of worked, except that if you
34 attempted to set the attribute after the object was created, you would get a
37 Now you will get an error when you attempt to define the attribute.
39 =item C<no Moose>, C<no Moose::Role>, and C<no Moose::Exporter> no longer unimport strict and warnings
41 This change was made in 1.05, and has now been reverted. We don't know if the
42 user has explicitly loaded strict or warnings on their own, and unimporting
43 them is just broken in that case.
45 =item Reversed logic when defining which options can be changed
47 L<Moose::Meta::Attribute> now allows all options to be changed in an
48 overridden attribute. The previous behaviour required each option to be
49 whitelisted using the C<legal_options_for_inheritance> method. This method has
50 been removed, and there is a new method, C<illegal_options_for_inheritance>,
51 which can now be used to prevent certain options from being changeable.
53 In addition, we only throw an error if the illegal option is actually
54 changed. If the superclass didn't specify this option at all when defining the
55 attribute, the subclass version can still add it as an option.
57 Example of overriding this in an attribute trait:
59 package Bar::Meta::Attribute;
62 has 'my_illegal_option' => (
67 around illegal_options_for_inheritance => sub {
68 return ( shift->(@_), qw/my_illegal_option/ );
77 =item L<Moose::Object/BUILD> methods are now called when calling C<new_object>
79 Previously, C<BUILD> methods would only be called from C<Moose::Object::new>,
80 but now they are also called when constructing an object via
81 C<Moose::Meta::Class::new_object>. C<BUILD> methods are an inherent part of the
82 object construction process, and this should make C<< $meta->new_object >>
83 actually usable without forcing people to use C<< $meta->name->new >>.
85 =item C<no Moose>, C<no Moose::Role>, and C<no Moose::Exporter> now unimport strict and warnings
87 In the interest of having C<no Moose> clean up everything that C<use Moose>
88 does in the calling scope, C<no Moose> (as well as all other
89 L<Moose::Exporter>-using modules) now unimports strict and warnings.
91 =item Metaclass compatibility checking and fixing should be much more robust
93 The L<metaclass compatibility|Moose/METACLASS COMPATIBILITY AND MOOSE> checking
94 and fixing algorithms have been completely rewritten, in both Class::MOP and
95 Moose. This should resolve many confusing errors when dealing with non-Moose
96 inheritance and with custom metaclasses for things like attributes,
97 constructors, etc. For correct code, the only thing that should require a
98 change is that custom error metaclasses must now inherit from
99 L<Moose::Error::Default>.
107 =item Moose::Meta::TypeConstraint::Class is_subtype_of behavior
109 Earlier versions of L<is_subtype_of|Moose::Meta::TypeConstraint::Class/is_subtype_of>
110 would incorrectly return true when called with itself, its own TC name or
111 its class name as an argument. (i.e. $foo_tc->is_subtype_of('Foo') == 1) This
112 behavior was a caused by C<isa> being checked before the class name. The old
113 behavior can be accessed with L<is_type_of|Moose::Meta::TypeConstraint::Class/is_type_of>
121 =item Moose::Meta::Attribute::Native::Trait::Code no longer creates reader methods by default
123 Earlier versions of L<Moose::Meta::Attribute::Native::Trait::Code> created
124 read-only accessors for the attributes it's been applied to, even if you didn't
125 ask for it with C<< is => 'ro' >>. This incorrect behaviour has now been fixed.
133 =item Moose::Util add_method_modifier behavior
135 add_method_modifier (and subsequently the sugar functions Moose::before,
136 Moose::after, and Moose::around) can now accept arrayrefs, with the same
137 behavior as lists. Types other than arrayref and regexp result in an error.
141 =head1 0.93_01 and 0.94
145 =item Moose::Util::MetaRole API has changed
147 The C<apply_metaclass_roles> function is now called C<apply_metaroles>. The
148 way arguments are supplied has been changed to force you to distinguish
149 between metaroles applied to L<Moose::Meta::Class> (and helpers) versus
150 L<Moose::Meta::Role>.
152 The old API still works, but will warn in a future release, and eventually be
155 =item Moose::Meta::Role has real attributes
157 The attributes returned by L<Moose::Meta::Role> are now instances of the
158 L<Moose::Meta::Role::Attribute> class, instead of bare hash references.
160 =item "no Moose" now removes C<blessed> and C<confess>
162 Moose is now smart enough to know exactly what it exported, even when it
163 re-exports functions from other packages. When you unimport Moose, it will
164 remove these functions from your namespace unless you I<also> imported them
165 directly from their respective packages.
167 If you have a C<no Moose> in your code I<before> you call C<blessed> or
168 C<confess>, your code will break. You can either move the C<no Moose> call
169 later in your code, or explicitly import the relevant functions from the
170 packages that provide them.
172 =item L<Moose::Exporter> is smarter about unimporting re-exports
174 The change above comes from a general improvement to L<Moose::Exporter>. It
175 will now unimport any function it exports, even if that function is a
176 re-export from another package.
178 =item Attributes in roles can no longer override class attributes with "+foo"
180 Previously, this worked more or less accidentally, because role attributes
181 weren't objects. This was never documented, but a few MooseX modules took
184 =item The composition_class_roles attribute in L<Moose::Meta::Role> is now a method
186 This was done to make it possible for roles to alter the the list of
187 composition class roles by applying a method modifiers. Previously, this was
188 an attribute and MooseX modules override it. Since that no longer works, this
191 This I<should> be an attribute, so this may switch back to being an attribute
192 in the future if we can figure out how to make this work.
200 =item Calling $object->new() is no longer deprecated
202 We decided to undeprecate this. Now it just works.
204 =item Both C<get_method_map> and C<get_attribute_map> is deprecated
206 These metaclass methods were never meant to be public, and they are both now
207 deprecated. The work around if you still need the functionality they provided
208 is to iterate over the list of names manually.
210 my %fields = map { $_ => $meta->get_attribute($_) } $meta->get_attribute_list;
212 This was actually a change in L<Class::MOP>, but this version of Moose
213 requires a version of L<Class::MOP> that includes said change.
221 =item Added Native delegation for Code refs
223 See L<Moose::Meta::Attribute::Native::Trait::Code> for details.
225 =item Calling $object->new() is deprecated
227 Moose has long supported this, but it's never really been documented, and we
228 don't think this is a good practice. If you want to construct an object from
229 an existing object, you should provide some sort of alternate constructor like
230 C<< $object->clone >>.
232 Calling C<< $object->new >> now issues a warning, and will be an error in a
235 =item Moose no longer warns if you call C<make_immutable> for a class with mutable ancestors
237 While in theory this is a good thing to warn about, we found so many
238 exceptions to this that doing this properly became quite problematic.
246 =item New Native delegation methods from L<List::Util> and L<List::MoreUtils>
248 In particular, we now have C<reduce>, C<shuffle>, C<uniq>, and C<natatime>.
250 =item The Moose::Exporter with_caller feature is now deprecated
252 Use C<with_meta> instead. The C<with_caller> option will start warning in a
255 =item Moose now warns if you call C<make_immutable> for a class with mutable ancestors
257 This is dangerous because modifying a class after a subclass has been
258 immutabilized will lead to incorrect results in the subclass, due to inlining,
259 caching, etc. This occasionally happens accidentally, when a class loads one
260 of its subclasses in the middle of its class definition, so pointing out that
261 this may cause issues should be helpful. Metaclasses (classes that inherit
262 from L<Class::MOP::Object>) are currently exempt from this check, since at the
263 moment we aren't very consistent about which metaclasses we immutabilize.
265 =item C<enum> and C<duck_type> now take arrayrefs for all forms
267 Previously, calling these functions with a list would take the first element of
268 the list as the type constraint name, and use the remainder as the enum values
269 or method names. This makes the interface inconsistent with the anon-type forms
270 of these functions (which must take an arrayref), and a free-form list where
271 the first value is sometimes special is hard to validate (and harder to give
272 reasonable error messages for). These functions have been changed to take
273 arrayrefs in all their forms - so, C<< enum 'My::Type' => [qw(foo bar)] >> is
274 now the preferred way to create an enum type constraint. The old syntax still
275 works for now, but it will hopefully be deprecated and removed in a future
282 L<Moose::Meta::Attribute::Native> has been moved into the Moose core from
283 L<MooseX::AttributeHelpers>. Major changes include:
287 =item C<traits>, not C<metaclass>
289 Method providers are only available via traits.
291 =item C<handles>, not C<provides> or C<curries>
293 The C<provides> syntax was like core Moose C<< handles => HASHREF >>
294 syntax, but with the keys and values reversed. This was confusing,
295 and AttributeHelpers now uses C<< handles => HASHREF >> in a way that
296 should be intuitive to anyone already familiar with how it is used for
299 The C<curries> functionality provided by AttributeHelpers has been
300 generalized to apply to all cases of C<< handles => HASHREF >>, though
301 not every piece of functionality has been ported (currying with a
302 CODEREF is not supported).
304 =item C<empty> is now C<is_empty>, and means empty, not non-empty
306 Previously, the C<empty> method provided by Arrays and Hashes returned true if
307 the attribute was B<not> empty (no elements). Now it returns true if the
308 attribute B<is> empty. It was also renamed to C<is_empty>, to reflect this.
310 =item C<find> was renamed to C<first>, and C<first> and C<last> were removed
312 L<List::Util> refers to the functionality that we used to provide under C<find>
313 as L<first|List::Util/first>, so that will likely be more familiar (and will
314 fit in better if we decide to add more List::Util functions). C<first> and
315 C<last> were removed, since their functionality is easily duplicated with
318 =item Helpers that take a coderef of one argument now use C<$_>
320 Subroutines passed as the first argument to C<first>, C<map>, and C<grep> now
321 receive their argument in C<$_> rather than as a parameter to the subroutine.
322 Helpers that take a coderef of two or more arguments remain using the argument
323 list (there are technical limitations to using C<$a> and C<$b> like C<sort>
326 See L<Moose::Meta::Attribute::Native> for the new documentation.
330 The C<alias> and C<excludes> role parameters have been renamed to C<-alias>
331 and C<-excludes>. The old names still work, but new code should use the new
332 names, and eventually the old ones will be deprecated and removed.
336 C<< use Moose -metaclass => 'Foo' >> now does alias resolution, just like
337 C<-traits> (and the C<metaclass> and C<traits> options to C<has>).
339 Added two functions C<meta_class_alias> and C<meta_attribute_alias> to
340 L<Moose::Util>, to simplify aliasing metaclasses and metatraits. This is
341 a wrapper around the old
343 package Moose::Meta::Class::Custom::Trait::FooTrait;
344 sub register_implementation { 'My::Meta::Trait' }
350 When an attribute generates I<no> accessors, we now warn. This is to help
351 users who forget the C<is> option. If you really do not want any accessors,
352 you can use C<< is => 'bare' >>. You can maintain back compat with older
353 versions of Moose by using something like:
355 ($Moose::VERSION >= 0.84 ? is => 'bare' : ())
357 When an accessor overwrites an existing method, we now warn. To work around
358 this warning (if you really must have this behavior), you can explicitly
359 remove the method before creating it as an accessor:
363 __PACKAGE__->meta->remove_method('foo');
369 When an unknown option is passed to C<has>, we now warn. You can silence
370 the warning by fixing your code. :)
372 The C<Role> type has been deprecated. On its own, it was useless,
373 since it just checked C<< $object->can('does') >>. If you were using
374 it as a parent type, just call C<role_type('Role::Name')> to create an
375 appropriate type instead.
379 C<use Moose::Exporter;> now imports C<strict> and C<warnings> into packages
384 C<DEMOLISHALL> and C<DEMOLISH> now receive an argument indicating whether or
385 not we are in global destruction.
389 Type constraints no longer run coercions for a value that already matches the
390 constraint. This may affect some (arguably buggy) edge case coercions that
391 rely on side effects in the C<via> clause.
395 L<Moose::Exporter> now accepts the C<-metaclass> option for easily
396 overriding the metaclass (without L<metaclass>). This works for classes
401 Added a C<duck_type> sugar function to L<Moose::Util::TypeConstraints>
402 to make integration with non-Moose classes easier. It simply checks if
403 C<< $obj->can() >> a list of methods.
405 A number of methods (mostly inherited from L<Class::MOP>) have been
406 renamed with a leading underscore to indicate their internal-ness. The
407 old method names will still work for a while, but will warn that the
408 method has been renamed. In a few cases, the method will be removed
409 entirely in the future. This may affect MooseX authors who were using
414 Calling C<subtype> with a name as the only argument now throws an
415 exception. If you want an anonymous subtype do:
417 my $subtype = subtype as 'Foo';
419 This is related to the changes in version 0.71_01.
421 The C<is_needed> method in L<Moose::Meta::Method::Destructor> is now
422 only usable as a class method. Previously, it worked as a class or
423 object method, with a different internal implementation for each
426 The internals of making a class immutable changed a lot in Class::MOP
427 0.78_02, and Moose's internals have changed along with it. The
428 external C<< $metaclass->make_immutable >> method still works the same
433 A mutable class accepted C<< Foo->new(undef) >> without complaint,
434 while an immutable class would blow up with an unhelpful error. Now,
435 in both cases we throw a helpful error instead.
437 This "feature" was originally added to allow for cases such as this:
445 return My::Class->new($args);
447 But we decided this is a bad idea and a little too magical, because it
448 can easily mask real errors.
452 Calling C<type> or C<subtype> without the sugar helpers (C<as>,
453 C<where>, C<message>) is now deprecated.
455 As a side effect, this meant we ended up using Perl prototypes on
456 C<as>, and code like this will no longer work:
458 use Moose::Util::TypeConstraints;
459 use Declare::Constraints::Simple -All;
461 subtype 'ArrayOfInts'
463 => IsArrayRef(IsInt);
465 Instead it must be changed to this:
470 where => IsArrayRef(IsInt)
474 If you want to maintain backwards compat with older versions of Moose,
475 you must explicitly test Moose's C<VERSION>:
477 if ( Moose->VERSION < 0.71_01 ) {
478 subtype 'ArrayOfInts'
480 => IsArrayRef(IsInt);
486 where => IsArrayRef(IsInt)
493 We no longer pass the meta-attribute object as a final argument to
494 triggers. This actually changed for inlined code a while back, but the
495 non-inlined version and the docs were still out of date.
497 If by some chance you actually used this feature, the workaround is
498 simple. You fetch the attribute object from out of the C<$self>
499 that is passed as the first argument to trigger, like so:
505 my ( $self, $value ) = @_;
506 my $attr = $self->meta->find_attribute_by_name('foo');
514 If you created a subtype and passed a parent that Moose didn't know
515 about, it simply ignored the parent. Now it automatically creates the
516 parent as a class type. This may not be what you want, but is less
519 You could declare a name with subtype such as "Foo!Bar". Moose would
520 accept this allowed, but if you used it in a parameterized type such
521 as "ArrayRef[Foo!Bar]" it wouldn't work. We now do some vetting on
522 names created via the sugar functions, so that they can only contain
523 alphanumerics, ":", and ".".
527 Methods created via an attribute can now fulfill a C<requires>
528 declaration for a role. Honestly we don't know why Stevan didn't make
529 this work originally, he was just insane or something.
531 Stack traces from inlined code will now report the line and file as
532 being in your class, as opposed to in Moose guts.
536 When a class does not provide all of a role's required methods, the
537 error thrown now mentions all of the missing methods, as opposed to
538 just the first missing method.
540 Moose will no longer inline a constructor for your class unless it
541 inherits its constructor from Moose::Object, and will warn when it
542 doesn't inline. If you want to force inlining anyway, pass
543 C<< replace_constructor => 1 >> to C<make_immutable>.
545 If you want to get rid of the warning, pass C<< inline_constructor =>
550 Removed the (deprecated) C<make_immutable> keyword.
552 Removing an attribute from a class now also removes delegation
553 (C<handles>) methods installed for that attribute. This is correct
554 behavior, but if you were wrongly relying on it you might get bit.
558 Roles now add methods by calling C<add_method>, not
559 C<alias_method>. They make sure to always provide a method object,
560 which will be cloned internally. This means that it is now possible to
561 track the source of a method provided by a role, and even follow its
562 history through intermediate roles. This means that methods added by
563 a role now show up when looking at a class's method list/map.
565 Parameter and Union args are now sorted, this makes Int|Str the same
566 constraint as Str|Int. Also, incoming type constraint strings are
567 normalized to remove all whitespace differences. This is mostly for
568 internals and should not affect outside code.
570 L<Moose::Exporter> will no longer remove a subroutine that the
571 exporting package re-exports. Moose re-exports the Carp::confess
572 function, among others. The reasoning is that we cannot know whether
573 you have also explicitly imported those functions for your own use, so
574 we err on the safe side and always keep them.
578 C<Moose::init_meta> should now be called as a method.
580 New modules for extension writers, L<Moose::Exporter> and
581 L<Moose::Util::MetaRole>.
585 Implemented metaclass traits (and wrote a recipe for it):
587 use Moose -traits => 'Foo'
589 This should make writing small Moose extensions a little
594 Fixed C<coerce> to accept anon types just like C<subtype> can.
597 coerce $some_anon_type => from 'Str' => via { ... };
601 Added C<BUILDARGS>, a new step in C<< Moose::Object->new() >>.
605 Fixed how the C<< is => (ro|rw) >> works with custom defined
606 C<reader>, C<writer> and C<accessor> options. See the below table for
609 is => ro, writer => _foo # turns into (reader => foo, writer => _foo)
610 is => rw, writer => _foo # turns into (reader => foo, writer => _foo)
611 is => rw, accessor => _foo # turns into (accessor => _foo)
612 is => ro, accessor => _foo # error, accesor is rw
616 The C<before/around/after> method modifiers now support regexp
617 matching of method names. NOTE: this only works for classes, it is
618 currently not supported in roles, but, ... patches welcome.
620 The C<has> keyword for roles now accepts the same array ref form that
621 L<Moose>.pm does for classes.
623 A trigger on a read-only attribute is no longer an error, as it's
624 useful to trigger off of the constructor.
626 Subtypes of parameterizable types now are parameterizable types
631 Fixed issue where C<DEMOLISHALL> was eating the value in C<$@>, and so
632 not working correctly. It still kind of eats them, but so does vanilla
637 Inherited attributes may now be extended without restriction on the
638 type ('isa', 'does').
640 The entire set of Moose::Meta::TypeConstraint::* classes were
641 refactored in this release. If you were relying on their internals you
642 should test your code carefully.
646 Documenting the use of '+name' with attributes that come from recently
647 composed roles. It makes sense, people are using it, and so why not
648 just officially support it.
650 The C<< Moose::Meta::Class->create >> method now supports roles.
652 It is now possible to make anonymous enum types by passing C<enum> an
653 array reference instead of the C<< enum $name => @values >>.
657 Added the C<make_immutable> keyword as a shortcut to calling
658 C<make_immutable> on the meta object. This eventually got removed!
660 Made C<< init_arg => undef >> work in Moose. This means "do not accept
661 a constructor parameter for this attribute".
663 Type errors now use the provided message. Prior to this release they
668 Moose is now a postmodern object system :)
670 The Role system was completely refactored. It is 100% backwards
671 compat, but the internals were totally changed. If you relied on the
672 internals then you are advised to test carefully.
674 Added method exclusion and aliasing for Roles in this release.
676 Added the L<Moose::Util::TypeConstraints::OptimizedConstraints>
679 Passing a list of values to an accessor (which is only expecting one
680 value) used to be silently ignored, now it throws an error.
684 Added parameterized types and did a pretty heavy refactoring of the
685 type constraint system.
687 Better framework extendability and better support for "making your own
690 =head1 0.25 or before
692 Honestly, you shouldn't be using versions of Moose that are this old,
693 so many bug fixes and speed improvements have been made you would be
694 crazy to not upgrade.
696 Also, I am tired of going through the Changelog so I am stopping here,
697 if anyone would like to continue this please feel free.
701 Stevan Little E<lt>stevan@iinteractive.comE<gt>
703 =head1 COPYRIGHT AND LICENSE
705 Copyright 2009 by Infinity Interactive, Inc.
707 L<http://www.iinteractive.com>
709 This library is free software; you can redistribute it and/or modify
710 it under the same terms as Perl itself.