Role::Tiny (3)
Leading comments
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NAME
Role::Tiny - Roles. Like a nouvelle cuisine portion size slice of Moose.SYNOPSIS
package Some::Role;
use Role::Tiny;
sub foo { ... }
sub bar { ... }
around baz => sub { ... };
1;
elsewhere
package Some::Class;
use Role::Tiny::With;
# bar gets imported, but not foo
with 'Some::Role';
sub foo { ... }
# baz is wrapped in the around modifier by Class::Method::Modifiers
sub baz { ... }
1;
If you wanted attributes as well, look at Moo::Role.
DESCRIPTION
"Role::Tiny" is a minimalist role composition tool.ROLE COMPOSITION
Role composition can be thought of as much more clever and meaningful multiple inheritance. The basics of this implementation of roles is:- *
- If a method is already defined on a class, that method will not be composed in from the role. A method inherited by a class gets overridden by the role's method of the same name, though.
- *
- If a method that the role ``requires'' to be implemented is not implemented, role application will fail loudly.
Unlike Class::C3, where the last class inherited from ``wins,'' role composition is the other way around, where the class wins. If multiple roles are applied in a single call (single with statement), then if any of their provided methods clash, an exception is raised unless the class provides a method since this conflict indicates a potential problem.
IMPORTED SUBROUTINES
requires
requires qw(foo bar);
Declares a list of methods that must be defined to compose role.
with
with 'Some::Role1'; with 'Some::Role1', 'Some::Role2';
Composes another role into the current role (or class via Role::Tiny::With).
If you have conflicts and want to resolve them in favour of Some::Role1 you can instead write:
with 'Some::Role1'; with 'Some::Role2';
If you have conflicts and want to resolve different conflicts in favour of different roles, please refactor your codebase.
before
before foo => sub { ... };
See ``before method(s) => sub { ... }'' in Class::Method::Modifiers for full documentation.
Note that since you are not required to use method modifiers, Class::Method::Modifiers is lazily loaded and we do not declare it as a dependency. If your Role::Tiny role uses modifiers you must depend on both Class::Method::Modifiers and Role::Tiny.
around
around foo => sub { ... };
See ``around method(s) => sub { ... }'' in Class::Method::Modifiers for full documentation.
Note that since you are not required to use method modifiers, Class::Method::Modifiers is lazily loaded and we do not declare it as a dependency. If your Role::Tiny role uses modifiers you must depend on both Class::Method::Modifiers and Role::Tiny.
after
after foo => sub { ... };
See ``after method(s) => sub { ... }'' in Class::Method::Modifiers for full documentation.
Note that since you are not required to use method modifiers, Class::Method::Modifiers is lazily loaded and we do not declare it as a dependency. If your Role::Tiny role uses modifiers you must depend on both Class::Method::Modifiers and Role::Tiny.
Strict and Warnings
In addition to importing subroutines, using "Role::Tiny" applies strict and warnings to the caller.SUBROUTINES
does_role
if (Role::Tiny::does_role($foo, 'Some::Role')) {
...
}
Returns true if class has been composed with role.
This subroutine is also installed as ->does on any class a Role::Tiny is composed into unless that class already has an ->does method, so
if ($foo->does('Some::Role')) {
...
}
will work for classes but to test a role, one must use ::does_role directly.
Additionally, Role::Tiny will override the standard Perl "DOES" method for your class. However, if "any" class in your class' inheritance hierarchy provides "DOES", then Role::Tiny will not override it.
METHODS
apply_roles_to_package
Role::Tiny->apply_roles_to_package( 'Some::Package', 'Some::Role', 'Some::Other::Role' );
Composes role with package. See also Role::Tiny::With.
apply_roles_to_object
Role::Tiny->apply_roles_to_object($foo, qw(Some::Role1 Some::Role2));
Composes roles in order into object directly. Object is reblessed into the resulting class. Note that the object's methods get overridden by the role's ones with the same names.
create_class_with_roles
Role::Tiny->create_class_with_roles('Some::Base', qw(Some::Role1 Some::Role2));
Creates a new class based on base, with the roles composed into it in order. New class is returned.
is_role
Role::Tiny->is_role('Some::Role1')
Returns true if the given package is a role.
CAVEATS
- *
- On perl 5.8.8 and earlier, applying a role to an object won't apply any overloads from the role to other copies of the object.
- *
- On perl 5.16 and earlier, applying a role to a class won't apply any overloads from the role to any existing instances of the class.
SEE ALSO
Role::Tiny is the attribute-less subset of Moo::Role; Moo::Role is a meta-protocol-less subset of the king of role systems, Moose::Role.Ovid's Role::Basic provides roles with a similar scope, but without method modifiers, and having some extra usage restrictions.
AUTHOR
mst - Matt S. Trout (cpan:MSTROUT) <mst@shadowcat.co.uk>CONTRIBUTORS
dg - David Leadbeater (cpan:DGL) <dgl@dgl.cx>frew - Arthur Axel ``fREW'' Schmidt (cpan:FREW) <frioux@gmail.com>
hobbs - Andrew Rodland (cpan:ARODLAND) <arodland@cpan.org>
jnap - John Napiorkowski (cpan:JJNAPIORK) <jjn1056@yahoo.com>
ribasushi - Peter Rabbitson (cpan:RIBASUSHI) <ribasushi@cpan.org>
chip - Chip Salzenberg (cpan:CHIPS) <chip@pobox.com>
ajgb - Alex J. G. Burzyński (cpan:AJGB) <ajgb@cpan.org>
doy - Jesse Luehrs (cpan:DOY) <doy at tozt dot net>
perigrin - Chris Prather (cpan:PERIGRIN) <chris@prather.org>
Mithaldu - Christian Walde (cpan:MITHALDU) <walde.christian@googlemail.com>
ilmari - Dagfinn Ilmari Mannsåker (cpan:ILMARI) <ilmari@ilmari.org>
tobyink - Toby Inkster (cpan:TOBYINK) <tobyink@cpan.org>
haarg - Graham Knop (cpan:HAARG) <haarg@haarg.org>