NAME Role::Tiny - Roles: 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) CONTRIBUTORS dg - David Leadbeater (cpan:DGL) frew - Arthur Axel "fREW" Schmidt (cpan:FREW) hobbs - Andrew Rodland (cpan:ARODLAND) jnap - John Napiorkowski (cpan:JJNAPIORK) ribasushi - Peter Rabbitson (cpan:RIBASUSHI) chip - Chip Salzenberg (cpan:CHIPS) ajgb - Alex J. G. Burzyński (cpan:AJGB) doy - Jesse Luehrs (cpan:DOY) perigrin - Chris Prather (cpan:PERIGRIN) Mithaldu - Christian Walde (cpan:MITHALDU) ilmari - Dagfinn Ilmari Mannsåker (cpan:ILMARI) tobyink - Toby Inkster (cpan:TOBYINK) haarg - Graham Knop (cpan:HAARG) COPYRIGHT Copyright (c) 2010-2012 the Role::Tiny "AUTHOR" and "CONTRIBUTORS" as listed above. LICENSE This library is free software and may be distributed under the same terms as perl itself.