Role::Tiny - Roles: a nouvelle cuisine portion size slice of Moose
Contents
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.
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.
Description
"Role::Tiny" is a minimalist role composition tool.
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.
StrictandWarnings
In addition to importing subroutines, using "Role::Tiny" applies strict and warnings to the caller.
License
This library is free software and may be distributed under the same terms as perl itself.
perl v5.32.0 2021-01-24 Role::Tiny(3pm)
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.
Name
Role::Tiny - Roles: a nouvelle cuisine portion size slice of Moose
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.
ROLEMETHODS
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.
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.
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.
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.
