3 sub _getglob { \*{$_[0]} }
4 sub _getstash { \%{"$_[0]::"} }
7 use warnings FATAL => 'all';
9 our $VERSION = '1.000001'; # 1.0.1
10 $VERSION = eval $VERSION;
16 # Module state workaround totally stolen from Zefram's Module::Runtime.
19 *_WORK_AROUND_BROKEN_MODULE_STATE = "$]" < 5.009 ? sub(){1} : sub(){0};
22 sub Role::Tiny::__GUARD__::DESTROY {
23 delete $INC{$_[0]->[0]} if @{$_[0]};
27 (my $proto = $_[0]) =~ s/::/\//g;
29 return 1 if $INC{$proto};
30 # can't just ->can('can') because a sub-package Foo::Bar::Baz
31 # creates a 'Baz::' key in Foo::Bar's symbol table
32 return 1 if grep !/::$/, keys %{_getstash($_[0])||{}};
33 my $guard = _WORK_AROUND_BROKEN_MODULE_STATE
34 && bless([ $proto ], 'Role::Tiny::__GUARD__');
36 pop @$guard if _WORK_AROUND_BROKEN_MODULE_STATE;
44 warnings->import(FATAL => 'all');
45 return if $INFO{$target}; # already exported into this package
46 # get symbol table reference
47 my $stash = do { no strict 'refs'; \%{"${target}::"} };
48 # install before/after/around subs
49 foreach my $type (qw(before after around)) {
50 *{_getglob "${target}::${type}"} = sub {
51 require Class::Method::Modifiers;
52 push @{$INFO{$target}{modifiers}||=[]}, [ $type => @_ ];
55 *{_getglob "${target}::requires"} = sub {
56 push @{$INFO{$target}{requires}||=[]}, @_;
58 *{_getglob "${target}::with"} = sub {
59 die "Only one role supported at a time by with" if @_ > 1;
60 $me->apply_role_to_package($target, $_[0]);
62 # grab all *non-constant* (stash slot is not a scalarref) subs present
63 # in the symbol table and store their refaddrs (no need to forcibly
64 # inflate constant subs into real subs) - also add '' to here (this
66 @{$INFO{$target}{not_methods}={}}{
67 '', map { *$_{CODE}||() } grep !ref($_), values %$stash
70 $APPLIED_TO{$target} = { $target => undef };
73 sub apply_role_to_package {
74 my ($me, $to, $role) = @_;
78 die "This is apply_role_to_package" if ref($to);
79 die "${role} is not a Role::Tiny" unless my $info = $INFO{$role};
81 $me->_check_requires($to, $role, @{$info->{requires}||[]});
83 $me->_install_methods($to, $role);
85 $me->_install_modifiers($to, $info->{modifiers});
87 # only add does() method to classes and only if they don't have one
88 if (not $INFO{$to} and not $to->can('does')) {
89 *{_getglob "${to}::does"} = \&does_role;
92 # copy our role list into the target's
93 @{$APPLIED_TO{$to}||={}}{keys %{$APPLIED_TO{$role}}} = ();
96 sub apply_roles_to_object {
97 my ($me, $object, @roles) = @_;
98 die "No roles supplied!" unless @roles;
99 my $class = ref($object);
100 bless($object, $me->create_class_with_roles($class, @roles));
104 sub create_class_with_roles {
105 my ($me, $superclass, @roles) = @_;
107 die "No roles supplied!" unless @roles;
110 '__WITH__', $superclass, my $compose_name = join '__AND__', @roles
113 return $new_name if $COMPOSED{class}{$new_name};
115 foreach my $role (@roles) {
117 die "${role} is not a Role::Tiny" unless $INFO{$role};
126 my @composable = map $me->_composable_package_for($_), reverse @roles;
128 *{_getglob("${new_name}::ISA")} = [ @composable, $superclass ];
130 my @info = map $INFO{$_}, @roles;
132 $me->_check_requires(
133 $new_name, $compose_name,
134 do { my %h; @h{map @{$_->{requires}||[]}, @info} = (); keys %h }
137 *{_getglob "${new_name}::does"} = \&does_role unless $new_name->can('does');
139 @{$APPLIED_TO{$new_name}||={}}{
140 map keys %{$APPLIED_TO{$_}}, @roles
143 $COMPOSED{class}{$new_name} = 1;
147 sub _composable_package_for {
148 my ($me, $role) = @_;
149 my $composed_name = 'Role::Tiny::_COMPOSABLE::'.$role;
150 return $composed_name if $COMPOSED{role}{$composed_name};
151 $me->_install_methods($composed_name, $role);
152 my $base_name = $composed_name.'::_BASE';
153 *{_getglob("${composed_name}::ISA")} = [ $base_name ];
154 my $modifiers = $INFO{$role}{modifiers}||[];
156 foreach my $modified (
157 do { my %h; @h{map $_->[1], @$modifiers} = (); keys %h }
159 push @mod_base, "sub ${modified} { shift->next::method(\@_) }";
164 eval(my $code = join "\n", "package ${base_name};", @mod_base);
165 $e = "Evaling failed: $@\nTrying to eval:\n${code}" if $@;
168 $me->_install_modifiers($composed_name, $modifiers);
169 $COMPOSED{role}{$composed_name} = 1;
170 return $composed_name;
173 sub _check_requires {
174 my ($me, $to, $name, @requires) = @_;
175 if (my @requires_fail = grep !$to->can($_), @requires) {
176 # role -> role, add to requires, role -> class, error out
177 if (my $to_info = $INFO{$to}) {
178 push @{$to_info->{requires}||=[]}, @requires_fail;
180 die "Can't apply ${name} to ${to} - missing ".join(', ', @requires_fail);
185 sub _concrete_methods_of {
186 my ($me, $role) = @_;
187 my $info = $INFO{$role};
188 $info->{methods} ||= do {
189 # grab role symbol table
190 my $stash = do { no strict 'refs'; \%{"${role}::"}};
191 my $not_methods = $info->{not_methods};
193 # grab all code entries that aren't in the not_methods list
195 my $code = *{$stash->{$_}}{CODE};
196 # rely on the '' key we added in import for "no code here"
197 exists $not_methods->{$code||''} ? () : ($_ => $code)
198 } grep !ref($stash->{$_}), keys %$stash
203 sub methods_provided_by {
204 my ($me, $role) = @_;
205 die "${role} is not a Role::Tiny" unless my $info = $INFO{$role};
206 (keys %{$me->_concrete_methods_of($role)}, @{$info->{requires}||[]});
209 sub _install_methods {
210 my ($me, $to, $role) = @_;
212 my $info = $INFO{$role};
214 my $methods = $me->_concrete_methods_of($role);
216 # grab target symbol table
217 my $stash = do { no strict 'refs'; \%{"${to}::"}};
219 # determine already extant methods of target
222 +(ref($stash->{$_}) || *{$stash->{$_}}{CODE}),
226 foreach my $i (grep !exists $has_methods{$_}, keys %$methods) {
228 *{_getglob "${to}::${i}"} = $methods->{$i};
232 sub _install_modifiers {
233 my ($me, $to, $modifiers) = @_;
234 if (my $info = $INFO{$to}) {
235 push @{$info->{modifiers}}, @{$modifiers||[]};
237 foreach my $modifier (@{$modifiers||[]}) {
238 $me->_install_single_modifier($to, @$modifier);
243 sub _install_single_modifier {
244 my ($me, @args) = @_;
245 Class::Method::Modifiers::install_modifier(@args);
249 my ($proto, $role) = @_;
250 return exists $APPLIED_TO{ref($proto)||$proto}{$role};
257 Role::Tiny - Roles. Like a nouvelle cuisine portion size slice of Moose.
269 around baz => sub { ... }
277 use Role::Tiny::With;
279 # bar gets imported, but not foo
284 # baz is wrapped in the around modifier by Class::Method::Modifiers
289 If you wanted attributes as well, look at L<Moo::Role>.
293 C<Role::Tiny> is a minimalist role composition tool.
295 =head1 ROLE COMPOSITION
297 Role composition can be thought of as much more clever and meaningful multiple
298 inheritance. The basics of this implementation of roles is:
304 If a method is already defined on a class, that method will not be composed in
309 If a method that the role L</requires> to be implemented is not implemented,
310 role application will fail loudly.
314 Unlike L<Class::C3>, where the B<last> class inherited from "wins," role
315 composition is the other way around, where first wins. In a more complete
316 system (see L<Moose>) roles are checked to see if they clash. The goal of this
317 is to be much simpler, hence disallowing composition of multiple roles at once.
321 =head2 apply_role_to_package
323 Role::Tiny->apply_role_to_package('Some::Package', 'Some::Role');
325 Composes role with package. See also L<Role::Tiny::With>.
327 =head2 apply_roles_to_object
329 Role::Tiny->apply_roles_to_object($foo, qw(Some::Role1 Some::Role2));
331 Composes roles in order into object directly. Object is reblessed into the
334 =head2 create_class_with_roles
336 Role::Tiny->create_class_with_roles('Some::Base', qw(Some::Role1 Some::Role2));
338 Creates a new class based on base, with the roles composed into it in order.
339 New class is returned.
345 if (Role::Tiny::does_role($foo, 'Some::Role')) {
349 Returns true if class has been composed with role.
351 This subroutine is also installed as ->does on any class a Role::Tiny is
352 composed into unless that class already has an ->does method, so
354 if ($foo->does('Some::Role')) {
358 will work for classes but to test a role, one must use ::does_role directly
360 =head1 IMPORTED SUBROUTINES
364 requires qw(foo bar);
366 Declares a list of methods that must be defined to compose role.
373 Composes another role into the current role. Only one role may be composed in
374 at a time to allow the code to remain as simple as possible.
378 before foo => sub { ... };
380 See L<< Class::Method::Modifiers/before method(s) => sub { ... } >> for full
383 Note that since you are not required to use method modifiers,
384 L<Class::Method::Modifiers> is lazily loaded and we do not declare it as
385 a dependency. If your L<Role::Tiny> role uses modifiers you must depend on
386 both L<Class::Method::Modifiers> and L<Role::Tiny>.
390 around foo => sub { ... };
392 See L<< Class::Method::Modifiers/around method(s) => sub { ... } >> for full
395 Note that since you are not required to use method modifiers,
396 L<Class::Method::Modifiers> is lazily loaded and we do not declare it as
397 a dependency. If your L<Role::Tiny> role uses modifiers you must depend on
398 both L<Class::Method::Modifiers> and L<Role::Tiny>.
402 after foo => sub { ... };
404 See L<< Class::Method::Modifiers/after method(s) => sub { ... } >> for full
407 Note that since you are not required to use method modifiers,
408 L<Class::Method::Modifiers> is lazily loaded and we do not declare it as
409 a dependency. If your L<Role::Tiny> role uses modifiers you must depend on
410 both L<Class::Method::Modifiers> and L<Role::Tiny>.
414 L<Role::Tiny> is the attribute-less subset of L<Moo::Role>; L<Moo::Role> is
415 a meta-protocol-less subset of the king of role systems, L<Moose::Role>.
417 If you don't want method modifiers and do want to be forcibly restricted
418 to a single role application per class, Ovid's L<Role::Basic> exists. But
419 Stevan Little (the L<Moose> author) and I are both still convinced that
424 mst - Matt S. Trout (cpan:MSTROUT) <mst@shadowcat.co.uk>
428 dg - David Leadbeater (cpan:DGL) <dgl@dgl.cx>
430 frew - Arthur Axel "fREW" Schmidt (cpan:FREW) <frioux@gmail.com>
432 hobbs - Andrew Rodland (cpan:ARODLAND) <arodland@cpan.org>
434 jnap - John Napiorkowski (cpan:JJNAPIORK) <jjn1056@yahoo.com>
436 ribasushi - Peter Rabbitson (cpan:RIBASUSHI) <ribasushi@cpan.org>
438 chip - Chip Salzenberg (cpan:CHIPS) <chip@pobox.com>
440 ajgb - Alex J. G. BurzyĆski (cpan:AJGB) <ajgb@cpan.org>
442 doy - Jesse Luehrs (cpan:DOY) <doy at tozt dot net>
444 perigrin - Chris Prather (cpan:PERIGRIN) <chris@prather.org>
448 Copyright (c) 2010-2012 the Role::Tiny L</AUTHOR> and L</CONTRIBUTORS>
453 This library is free software and may be distributed under the same terms