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.
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 and mymethod will be included when composing MyRole, and min and mysub 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 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
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 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) <[email protected]>
CONTRIBUTORS
dg - David Leadbeater (cpan:DGL) <[email protected]>
frew - Arthur Axel "fREW" Schmidt (cpan:FREW) <[email protected]>
hobbs - Andrew Rodland (cpan:ARODLAND) <[email protected]>
jnap - John Napiorkowski (cpan:JJNAPIORK) <[email protected]>
ribasushi - Peter Rabbitson (cpan:RIBASUSHI) <[email protected]>
chip - Chip Salzenberg (cpan:CHIPS) <[email protected]>
ajgb - Alex J. G. Burzyński (cpan:AJGB) <[email protected]>
doy - Jesse Luehrs (cpan:DOY) <doy at tozt dot net>
perigrin - Chris Prather (cpan:PERIGRIN) <[email protected]>
Mithaldu - Christian Walde (cpan:MITHALDU) <[email protected]>
ilmari - Dagfinn Ilmari Mannsåker (cpan:ILMARI) <[email protected]>
tobyink - Toby Inkster (cpan:TOBYINK) <[email protected]>
haarg - Graham Knop (cpan:HAARG) <[email protected]>
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.