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 foowith 'Some::Role';sub foo { ... }# baz is wrapped in the around modifier by Class::Method::Modifierssub baz { ... }1;

If you wanted attributes as well, look atMoo::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.

UnlikeClass::C3, where thelast 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.

ROLE METHODS

All subs created after importing Role::Tiny will be considered methods to be composed. For example:

package MyRole;use List::Util qw(min);sub mysub { }use Role::Tiny;use List::Util qw(max);sub mymethod { }

In this role,max andmymethod will be included when composing MyRole, andmin andmysub will not. For additional control,namespace::clean can be used to exclude undesired subs from roles.

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 viaRole::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 yourRole::Tiny role uses modifiers you must depend on bothClass::Method::Modifiers andRole::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 yourRole::Tiny role uses modifiers you must depend on bothClass::Method::Modifiers andRole::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 yourRole::Tiny role uses modifiers you must depend on bothClass::Method::Modifiers andRole::Tiny.

Strict and Warnings

In addition to importing subroutines, usingRole::Tiny appliesstrict andwarnings 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 PerlDOES method for your class. However, ifany class in your class' inheritance hierarchy providesDOES, then Role::Tiny will not override it.

METHODS

make_role

Role::Tiny->make_role('Some::Role');

Makes a package into a role, but does not export any subs into it.

apply_roles_to_package

Role::Tiny->apply_roles_to_package(  'Some::Package', 'Some::Role', 'Some::Other::Role');

Composes role with package. See alsoRole::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 ofMoo::Role;Moo::Role is a meta-protocol-less subset of the king of role systems,Moose::Role.

Ovid'sRole::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>

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.