Role::Tiny

Section: User Contributed Perl Documentation (3)
Updated: 2020-01-30
Page Index
 

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

 

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) <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.


 

Index

NAME
SYNOPSIS
DESCRIPTION
ROLE COMPOSITION
IMPORTED SUBROUTINES
requires
with
before
around
after
Strict and Warnings
SUBROUTINES
does_role
METHODS
make_role
apply_roles_to_package
apply_roles_to_object
create_class_with_roles
is_role
CAVEATS
SEE ALSO
AUTHOR
CONTRIBUTORS
COPYRIGHT
LICENSE
LinuxReviews : manual page archive : man3pm