| Moose::Manual::Delta(3) | User Contributed Perl Documentation | Moose::Manual::Delta(3) |
Moose::Manual::Delta - Important Changes in Moose
version 2.2012
This documents any important or noteworthy changes in Moose, with a focus on things that affect backwards compatibility. This does duplicate data from the Changes file, but aims to provide more details and when possible workarounds.
Besides helping keep up with changes, you can also use this document for finding the lowest version of Moose that supported a given feature. If you encounter a problem and have a solution but don't see it documented here, or think we missed an important feature, please send us a patch.
All of the overloading-related methods for classes and roles have the same names, but those methods now return Class::MOP::Overload objects.
This works much like MooseX::Role::WithOverloading, except that we properly detect overloading conflicts during role summation and when applying one role to another. MooseX::Role::WithOverloading did not do any conflict detection.
If you want to write code that uses overloading and works with previous versions of Moose and this one, upgrade to MooseX::Role::WithOverloading version 0.15 or greater. That version will detect when Moose itself handles overloading and get out of the way.
{
package Foo;
use Moose;
}
# ...
use Foo;
If you're using the MOP, this behavior will occur when the "create" (or "create_anon_class") method is used, but not when the "initialize" method is used.
Now, Moose uses the same mechanisms as perl itself to figure out if a class is loaded. A class is considered to be loaded if its entry in %INC is set. Perl sets the %INC entry for you automatically whenever a file is loaded via "use" or "require". Also, as mentioned above, Moose also now sets the %INC entry for any classes defined with it, even if they aren't loaded from a separate file. This does however mean that if you are trying to use Moose with non-Moose classes defined in the same file, then you will need to set %INC manually now, where it may have worked in the past. For instance:
{
package My::NonMoose;
sub new { bless {}, shift }
$INC{'My/NonMoose.pm'} = __FILE__;
# alternatively:
# use Module::Runtime 'module_notional_filename';
# $INC{module_notional_filename(__PACKAGE__)} = __FILE__;
}
{
package My::Moose;
use Moose;
extends 'My::NonMoose';
}
If you don't do this, you will get an error message about not being able to locate "My::NonMoose" in @INC. We hope that this case will be fairly rare.
enum('MyType' => qw(foo bar baz))
This was confusing, however (since it was different from the syntax for anonymous enum types), and it makes error checking more difficult (since you can't tell just by looking whether "enum('Foo', 'Bar', 'Baz')" was intended to be a type named "Foo" with elements of "Bar" and "Baz", or if this was actually a mistake where someone got the syntax for an anonymous enum type wrong). This all also applies to "duck_type".
Calling "enum" and "duck_type" with a list of arguments as described above has been undocumented since version 0.93, and is now deprecated. You should replace
enum MyType => qw(foo bar baz);
in your code with
enum MyType => [qw(foo bar baz)];
For learning about the usage of Moose exception objects, read Moose::Manual::Exceptions. Individual exceptions are documented in Moose::Manual::Exceptions::Manifest.
This work was funded as part of the GNOME Outreach Program for Women.
If you want the old behavior you can use the "LaxNum" type in MooseX::Types::LaxNum.
This also means that you can now apply method modifiers to these methods.
Use the inlining feature ("inline_as") added in 2.0100 instead.
This affects the "optimize_as" sub exported by Moose::Util::TypeConstraints. Use "inline_as" instead.
This will start warning in the 2.0300 release.
Attribute (foo) does not pass the type constraint because: Validation failed for 'ArrayRef[Int]' with value ARRAY(0x275eed8)
the error message will instead look like
Attribute (foo) does not pass the type constraint because: Validation failed for 'ArrayRef[Int]' with value [ "a" ]
Note that Devel::PartialDump can't be made a direct dependency at the moment, because it uses Moose itself, but we're considering options to make this easier.
Moose::Util::MetaRole::apply_metaroles(
for => __PACKAGE__,
class_metaroles => {
attribute => ['My::Meta::Role::Attribute'],
},
role_metaroles => {
applied_attribute => ['My::Meta::Role::Attribute'],
},
);
The other part is that Moose's "META.json" file will also specify the conflicts under the "x_conflicts" (now "x_breaks") key. We are working with the Perl tool chain developers to try to get conflicts support added to CPAN clients, and if/when that happens, the metadata already exists, and so the conflict checking will become automatic.
The things on the chopping block are:
This includes things like "Class::MOP::Class->get_attribute_map", "Class::MOP::Class->construct_instance", and many others. These were deprecated in Class::MOP 0.80_01, released on April 5, 2009.
These methods will be removed entirely in Moose 2.0200.
This include "Class::MOP::subname", "Class::MOP::in_global_destruction", and the "Class::MOP::HAS_ISAREV" constant. The first two were deprecated in 0.84, and the last in 0.80. Class::MOP 0.84 was released on May 12, 2009.
These functions will be removed entirely in Moose 2.0200.
These were renamed to "-alias" and "-excludes" in Moose 0.89, released on August 13, 2009.
Passing these will throw an error in Moose 2.0200.
This include the "apply_metaclass_roles()" function, as well as passing the "for_class" or any key ending in "_roles" to "apply_metaroles()". This was deprecated in Moose 0.93_01, released on January 4, 2010.
These will all throw an error in Moose 2.0200.
The old API for these functions allowed you to pass a plain list of parameter, rather than a list of hash references (which is what "as()", "where", etc. return). This was deprecated in Moose 0.71_01, released on February 22, 2009.
This will throw an error in Moose 2.0200.
This subtype was deprecated in Moose 0.84, released on June 26, 2009.
This will be removed entirely in Moose 2.0200.
As of the 2.0 release, Moose now has an official release and support policy, documented in Moose::Manual::Support. All API changes will now go through a deprecation cycle of at least one year, after which the deprecated API can be removed. Deprecations and removals will only happen in major releases.
In between major releases, we will still make minor releases to add new features, fix bugs, update documentation, etc.
push @{ $self->$reader() }, @_;
If the attribute was created without a reader, the $reader sub reference followed a very slow code path. Even with a reader, this is still slower than it needs to be.
Native delegations are now generated as inline code, just like other accessors, so we can access the slot directly.
In addition, native traits now do proper constraint checking in all cases. In particular, constraint checking has been improved for array and hash references. Previously, only the contained type (the "Str" in "HashRef[Str]") would be checked when a new value was added to the collection. However, if there was a constraint that applied to the whole value, this was never checked.
In addition, coercions are now called on the whole value.
The delegation methods now do more argument checking. All of the methods check that a valid number of arguments were passed to the method. In addition, the delegation methods check that the arguments are sane (array indexes, hash keys, numbers, etc.) when applicable. We have tried to emulate the behavior of Perl builtins as much as possible.
Finally, triggers are called whenever the value of the attribute is changed by a Native delegation.
These changes are only likely to break code in a few cases.
The inlining code may or may not preserve the original reference when changes are made. In some cases, methods which change the value may replace it entirely. This will break tied values.
If you have a typed arrayref or hashref attribute where the type enforces a constraint on the whole collection, this constraint will now be checked. It's possible that code which previously ran without errors will now cause the constraint to fail. However, presumably this is a good thing ;)
If you are passing invalid arguments to a delegation which were previously being ignored, these calls will now fail.
If your code relied on the trigger only being called for a regular writer, that may cause problems.
As always, you are encouraged to test before deploying the latest version of Moose to production.
Now you will get a warning when you attempt to define the attribute.
In addition, we only throw an error if the illegal option is actually changed. If the superclass didn't specify this option at all when defining the attribute, the subclass version can still add it as an option.
Example of overriding this in an attribute trait:
package Bar::Meta::Attribute;
use Moose::Role;
has 'my_illegal_option' => (
isa => 'CodeRef',
is => 'rw',
);
around illegal_options_for_inheritance => sub {
return ( shift->(@_), qw/my_illegal_option/ );
};
The old API still works, but will warn in a future release, and eventually be removed.
If you have a "no Moose" in your code before you call "blessed" or "confess", your code will break. You can either move the "no Moose" call later in your code, or explicitly import the relevant functions from the packages that provide them.
This should be an attribute, so this may switch back to being an attribute in the future if we can figure out how to make this work.
my %fields = map { $_ => $meta->get_attribute($_) } $meta->get_attribute_list;
This was actually a change in Class::MOP, but this version of Moose requires a version of Class::MOP that includes said change.
Calling "$object->new" now issues a warning, and will be an error in a future release.
Moose::Meta::Attribute::Native has been moved into the Moose core from MooseX::AttributeHelpers. Major changes include:
The "curries" functionality provided by AttributeHelpers has been generalized to apply to all cases of "handles => HASHREF", though not every piece of functionality has been ported (currying with a CODEREF is not supported).
See Moose::Meta::Attribute::Native for the new documentation.
The "alias" and "excludes" role parameters have been renamed to "-alias" and "-excludes". The old names still work, but new code should use the new names, and eventually the old ones will be deprecated and removed.
"use Moose -metaclass => 'Foo'" now does alias resolution, just like "-traits" (and the "metaclass" and "traits" options to "has").
Added two functions "meta_class_alias" and "meta_attribute_alias" to Moose::Util, to simplify aliasing metaclasses and metatraits. This is a wrapper around the old
package Moose::Meta::Class::Custom::Trait::FooTrait;
sub register_implementation { 'My::Meta::Trait' }
way of doing this.
When an attribute generates no accessors, we now warn. This is to help users who forget the "is" option. If you really do not want any accessors, you can use "is => 'bare'". You can maintain back compat with older versions of Moose by using something like:
($Moose::VERSION >= 0.84 ? is => 'bare' : ())
When an accessor overwrites an existing method, we now warn. To work around this warning (if you really must have this behavior), you can explicitly remove the method before creating it as an accessor:
sub foo {}
__PACKAGE__->meta->remove_method('foo');
has foo => (
is => 'ro',
);
When an unknown option is passed to "has", we now warn. You can silence the warning by fixing your code. :)
The "Role" type has been deprecated. On its own, it was useless, since it just checked "$object->can('does')". If you were using it as a parent type, just call "role_type('Role::Name')" to create an appropriate type instead.
"use Moose::Exporter;" now imports "strict" and "warnings" into packages that use it.
"DEMOLISHALL" and "DEMOLISH" now receive an argument indicating whether or not we are in global destruction.
Type constraints no longer run coercions for a value that already matches the constraint. This may affect some (arguably buggy) edge case coercions that rely on side effects in the "via" clause.
Moose::Exporter now accepts the "-metaclass" option for easily overriding the metaclass (without metaclass). This works for classes and roles.
Added a "duck_type" sugar function to Moose::Util::TypeConstraints to make integration with non-Moose classes easier. It simply checks if "$obj->can()" a list of methods.
A number of methods (mostly inherited from Class::MOP) have been renamed with a leading underscore to indicate their internal-ness. The old method names will still work for a while, but will warn that the method has been renamed. In a few cases, the method will be removed entirely in the future. This may affect MooseX authors who were using these methods.
Calling "subtype" with a name as the only argument now throws an exception. If you want an anonymous subtype do:
my $subtype = subtype as 'Foo';
This is related to the changes in version 0.71_01.
The "is_needed" method in Moose::Meta::Method::Destructor is now only usable as a class method. Previously, it worked as a class or object method, with a different internal implementation for each version.
The internals of making a class immutable changed a lot in Class::MOP 0.78_02, and Moose's internals have changed along with it. The external "$metaclass->make_immutable" method still works the same way.
A mutable class accepted "Foo->new(undef)" without complaint, while an immutable class would blow up with an unhelpful error. Now, in both cases we throw a helpful error instead.
This "feature" was originally added to allow for cases such as this:
my $args;
if ( something() ) {
$args = {...};
}
return My::Class->new($args);
But we decided this is a bad idea and a little too magical, because it can easily mask real errors.
Calling "type" or "subtype" without the sugar helpers ("as", "where", "message") is now deprecated.
As a side effect, this meant we ended up using Perl prototypes on "as", and code like this will no longer work:
use Moose::Util::TypeConstraints;
use Declare::Constraints::Simple -All;
subtype 'ArrayOfInts'
=> as 'ArrayRef'
=> IsArrayRef(IsInt);
Instead it must be changed to this:
subtype(
'ArrayOfInts' => {
as => 'ArrayRef',
where => IsArrayRef(IsInt)
}
);
If you want to maintain backwards compat with older versions of Moose, you must explicitly test Moose's "VERSION":
if ( Moose->VERSION < 0.71_01 ) {
subtype 'ArrayOfInts'
=> as 'ArrayRef'
=> IsArrayRef(IsInt);
}
else {
subtype(
'ArrayOfInts' => {
as => 'ArrayRef',
where => IsArrayRef(IsInt)
}
);
}
We no longer pass the meta-attribute object as a final argument to triggers. This actually changed for inlined code a while back, but the non-inlined version and the docs were still out of date.
If by some chance you actually used this feature, the workaround is simple. You fetch the attribute object from out of the $self that is passed as the first argument to trigger, like so:
has 'foo' => (
is => 'ro',
isa => 'Any',
trigger => sub {
my ( $self, $value ) = @_;
my $attr = $self->meta->find_attribute_by_name('foo');
# ...
}
);
If you created a subtype and passed a parent that Moose didn't know about, it simply ignored the parent. Now it automatically creates the parent as a class type. This may not be what you want, but is less broken than before.
You could declare a name with subtype such as "Foo!Bar". Moose would accept this allowed, but if you used it in a parameterized type such as "ArrayRef[Foo!Bar]" it wouldn't work. We now do some vetting on names created via the sugar functions, so that they can only contain alphanumerics, ":", and ".".
Methods created via an attribute can now fulfill a "requires" declaration for a role. Honestly we don't know why Stevan didn't make this work originally, he was just insane or something.
Stack traces from inlined code will now report the line and file as being in your class, as opposed to in Moose guts.
When a class does not provide all of a role's required methods, the error thrown now mentions all of the missing methods, as opposed to just the first missing method.
Moose will no longer inline a constructor for your class unless it inherits its constructor from Moose::Object, and will warn when it doesn't inline. If you want to force inlining anyway, pass "replace_constructor => 1" to "make_immutable".
If you want to get rid of the warning, pass "inline_constructor => 0".
Removed the (deprecated) "make_immutable" keyword.
Removing an attribute from a class now also removes delegation ("handles") methods installed for that attribute. This is correct behavior, but if you were wrongly relying on it you might get bit.
Roles now add methods by calling "add_method", not "alias_method". They make sure to always provide a method object, which will be cloned internally. This means that it is now possible to track the source of a method provided by a role, and even follow its history through intermediate roles. This means that methods added by a role now show up when looking at a class's method list/map.
Parameter and Union args are now sorted, this makes Int|Str the same constraint as Str|Int. Also, incoming type constraint strings are normalized to remove all whitespace differences. This is mostly for internals and should not affect outside code.
Moose::Exporter will no longer remove a subroutine that the exporting package re-exports. Moose re-exports the Carp::confess function, among others. The reasoning is that we cannot know whether you have also explicitly imported those functions for your own use, so we err on the safe side and always keep them.
"Moose::init_meta" should now be called as a method.
New modules for extension writers, Moose::Exporter and Moose::Util::MetaRole.
Implemented metaclass traits (and wrote a recipe for it):
use Moose -traits => 'Foo'
This should make writing small Moose extensions a little easier.
Fixed "coerce" to accept anon types just like "subtype" can. So that you can do:
coerce $some_anon_type => from 'Str' => via { ... };
Added "BUILDARGS", a new step in "Moose::Object->new()".
Fixed how the "is => (ro|rw)" works with custom defined "reader", "writer" and "accessor" options. See the below table for details:
is => ro, writer => _foo # turns into (reader => foo, writer => _foo) is => rw, writer => _foo # turns into (reader => foo, writer => _foo) is => rw, accessor => _foo # turns into (accessor => _foo) is => ro, accessor => _foo # error, accesor is rw
The "before/around/after" method modifiers now support regexp matching of method names. NOTE: this only works for classes, it is currently not supported in roles, but, ... patches welcome.
The "has" keyword for roles now accepts the same array ref form that Moose.pm does for classes.
A trigger on a read-only attribute is no longer an error, as it's useful to trigger off of the constructor.
Subtypes of parameterizable types now are parameterizable types themselves.
Fixed issue where "DEMOLISHALL" was eating the value in $@, and so not working correctly. It still kind of eats them, but so does vanilla perl.
Inherited attributes may now be extended without restriction on the type ('isa', 'does').
The entire set of Moose::Meta::TypeConstraint::* classes were refactored in this release. If you were relying on their internals you should test your code carefully.
Documenting the use of '+name' with attributes that come from recently composed roles. It makes sense, people are using it, and so why not just officially support it.
The "Moose::Meta::Class->create" method now supports roles.
It is now possible to make anonymous enum types by passing "enum" an array reference instead of the "enum $name => @values".
Added the "make_immutable" keyword as a shortcut to calling "make_immutable" on the meta object. This eventually got removed!
Made "init_arg => undef" work in Moose. This means "do not accept a constructor parameter for this attribute".
Type errors now use the provided message. Prior to this release they didn't.
Moose is now a postmodern object system :)
The Role system was completely refactored. It is 100% backwards compat, but the internals were totally changed. If you relied on the internals then you are advised to test carefully.
Added method exclusion and aliasing for Roles in this release.
Added the Moose::Util::TypeConstraints::OptimizedConstraints module.
Passing a list of values to an accessor (which is only expecting one value) used to be silently ignored, now it throws an error.
Added parameterized types and did a pretty heavy refactoring of the type constraint system.
Better framework extensibility and better support for "making your own Moose".
Honestly, you shouldn't be using versions of Moose that are this old, so many bug fixes and speed improvements have been made you would be crazy to not upgrade.
Also, I am tired of going through the Changelog so I am stopping here, if anyone would like to continue this please feel free.
This software is copyright (c) 2006 by Infinity Interactive, Inc.
This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.
| 2019-11-22 | perl v5.34.0 |