3 sub _getglob { \*{$_[0]} }
4 sub _getstash { \%{"$_[0]::"} }
7 use warnings FATAL => 'all';
9 our $VERSION = '1.000_900'; # 1.0.900
10 $VERSION = eval $VERSION;
17 # Module state workaround totally stolen from Zefram's Module::Runtime.
20 *_WORK_AROUND_BROKEN_MODULE_STATE = "$]" < 5.009 ? sub(){1} : sub(){0};
23 sub Role::Tiny::__GUARD__::DESTROY {
24 delete $INC{$_[0]->[0]} if @{$_[0]};
28 (my $proto = $_[0]) =~ s/::/\//g;
30 return 1 if $INC{$proto};
31 # can't just ->can('can') because a sub-package Foo::Bar::Baz
32 # creates a 'Baz::' key in Foo::Bar's symbol table
33 return 1 if grep !/::$/, keys %{_getstash($_[0])||{}};
34 my $guard = _WORK_AROUND_BROKEN_MODULE_STATE
35 && bless([ $proto ], 'Role::Tiny::__GUARD__');
37 pop @$guard if _WORK_AROUND_BROKEN_MODULE_STATE;
45 warnings->import(FATAL => 'all');
46 return if $INFO{$target}; # already exported into this package
47 # get symbol table reference
48 my $stash = do { no strict 'refs'; \%{"${target}::"} };
49 # install before/after/around subs
50 foreach my $type (qw(before after around)) {
51 *{_getglob "${target}::${type}"} = sub {
52 require Class::Method::Modifiers;
53 push @{$INFO{$target}{modifiers}||=[]}, [ $type => @_ ];
56 *{_getglob "${target}::requires"} = sub {
57 push @{$INFO{$target}{requires}||=[]}, @_;
59 *{_getglob "${target}::with"} = sub {
60 $me->apply_roles_to_package($target, @_);
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} = { $target => undef };
73 sub apply_single_role_to_package {
74 my ($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;
111 $seen{$_}++ for @roles;
112 if (my @dupes = grep $seen{$_} > 1, @roles) {
113 die "Duplicated roles: ".join(', ', @dupes);
118 '__WITH__', $superclass, my $compose_name = join '__AND__', @roles
121 return $new_name if $COMPOSED{class}{$new_name};
123 foreach my $role (@roles) {
125 die "${role} is not a Role::Tiny" unless $INFO{$role};
134 my @composable = map $me->_composable_package_for($_), reverse @roles;
136 *{_getglob("${new_name}::ISA")} = [ @composable, $superclass ];
138 my @info = map $INFO{$_}, @roles;
140 $me->_check_requires(
141 $new_name, $compose_name,
142 do { my %h; @h{map @{$_->{requires}||[]}, @info} = (); keys %h }
145 *{_getglob "${new_name}::does"} = \&does_role unless $new_name->can('does');
147 @{$APPLIED_TO{$new_name}||={}}{
148 map keys %{$APPLIED_TO{$_}}, @roles
151 $COMPOSED{class}{$new_name} = 1;
155 sub apply_role_to_package { shift->apply_single_role_to_package(@_) }
157 sub apply_roles_to_package {
158 my ($me, $to, @roles) = @_;
160 return $me->apply_single_role_to_package($to, $roles[0]) if @roles == 1;
162 my %conflicts = %{$me->_composite_info_for(@roles)->{conflicts}};
163 delete $conflicts{$_} for $me->_concrete_methods_of($to);
164 if (keys %conflicts) {
168 "Due to a method name conflict between roles "
169 ."'".join(' and ', sort values %{$conflicts{$_}})."'"
170 .", the method '$_' must be implemented by '${to}'"
174 delete $INFO{$to}{methods}; # reset since we're about to add methods
175 $me->apply_single_role_to_package($to, $_) for @roles;
176 $APPLIED_TO{$to}{join('|',@roles)} = 1;
179 sub _composite_info_for {
180 my ($me, @roles) = @_;
181 $COMPOSITE_INFO{join('|', sort @roles)} ||= do {
182 _load_module($_) for @roles;
184 foreach my $role (@roles) {
185 my $this_methods = $me->_concrete_methods_of($role);
186 $methods{$_}{$this_methods->{$_}} = $role for keys %$this_methods;
188 delete $methods{$_} for grep keys(%{$methods{$_}}) == 1, keys %methods;
189 +{ conflicts => \%methods }
193 sub _composable_package_for {
194 my ($me, $role) = @_;
195 my $composed_name = 'Role::Tiny::_COMPOSABLE::'.$role;
196 return $composed_name if $COMPOSED{role}{$composed_name};
197 $me->_install_methods($composed_name, $role);
198 my $base_name = $composed_name.'::_BASE';
199 *{_getglob("${composed_name}::ISA")} = [ $base_name ];
200 my $modifiers = $INFO{$role}{modifiers}||[];
202 foreach my $modified (
203 do { my %h; @h{map $_->[1], @$modifiers} = (); keys %h }
205 push @mod_base, "sub ${modified} { shift->next::method(\@_) }";
210 eval(my $code = join "\n", "package ${base_name};", @mod_base);
211 $e = "Evaling failed: $@\nTrying to eval:\n${code}" if $@;
214 $me->_install_modifiers($composed_name, $modifiers);
215 $COMPOSED{role}{$composed_name} = 1;
216 return $composed_name;
219 sub _check_requires {
220 my ($me, $to, $name, @requires) = @_;
221 if (my @requires_fail = grep !$to->can($_), @requires) {
222 # role -> role, add to requires, role -> class, error out
223 if (my $to_info = $INFO{$to}) {
224 push @{$to_info->{requires}||=[]}, @requires_fail;
226 die "Can't apply ${name} to ${to} - missing ".join(', ', @requires_fail);
231 sub _concrete_methods_of {
232 my ($me, $role) = @_;
233 my $info = $INFO{$role};
234 # grab role symbol table
235 my $stash = do { no strict 'refs'; \%{"${role}::"}};
236 my $not_methods = $info->{not_methods};
237 $info->{methods} ||= +{
238 # grab all code entries that aren't in the not_methods list
240 my $code = *{$stash->{$_}}{CODE};
241 # rely on the '' key we added in import for "no code here"
242 exists $not_methods->{$code||''} ? () : ($_ => $code)
243 } grep !ref($stash->{$_}), keys %$stash
247 sub methods_provided_by {
248 my ($me, $role) = @_;
249 die "${role} is not a Role::Tiny" unless my $info = $INFO{$role};
250 (keys %{$me->_concrete_methods_of($role)}, @{$info->{requires}||[]});
253 sub _install_methods {
254 my ($me, $to, $role) = @_;
256 my $info = $INFO{$role};
258 my $methods = $me->_concrete_methods_of($role);
260 # grab target symbol table
261 my $stash = do { no strict 'refs'; \%{"${to}::"}};
263 # determine already extant methods of target
266 +(ref($stash->{$_}) || *{$stash->{$_}}{CODE}),
270 foreach my $i (grep !exists $has_methods{$_}, keys %$methods) {
272 *{_getglob "${to}::${i}"} = $methods->{$i};
276 sub _install_modifiers {
277 my ($me, $to, $modifiers) = @_;
278 if (my $info = $INFO{$to}) {
279 push @{$info->{modifiers}}, @{$modifiers||[]};
281 foreach my $modifier (@{$modifiers||[]}) {
282 $me->_install_single_modifier($to, @$modifier);
287 sub _install_single_modifier {
288 my ($me, @args) = @_;
289 Class::Method::Modifiers::install_modifier(@args);
293 my ($proto, $role) = @_;
294 return exists $APPLIED_TO{ref($proto)||$proto}{$role};
301 Role::Tiny - Roles. Like a nouvelle cuisine portion size slice of Moose.
313 around baz => sub { ... }
321 use Role::Tiny::With;
323 # bar gets imported, but not foo
328 # baz is wrapped in the around modifier by Class::Method::Modifiers
333 If you wanted attributes as well, look at L<Moo::Role>.
337 C<Role::Tiny> is a minimalist role composition tool.
339 =head1 ROLE COMPOSITION
341 Role composition can be thought of as much more clever and meaningful multiple
342 inheritance. The basics of this implementation of roles is:
348 If a method is already defined on a class, that method will not be composed in
353 If a method that the role L</requires> to be implemented is not implemented,
354 role application will fail loudly.
358 Unlike L<Class::C3>, where the B<last> class inherited from "wins," role
359 composition is the other way around, where the class wins. If multiple roles
360 are applied in a single call (single with statement), then if any of their
361 provided methods clash, an exception is raised unless the class provides
362 a method since this conflict indicates a potential problem.
366 =head2 apply_roles_to_package
368 Role::Tiny->apply_roles_to_package(
369 'Some::Package', 'Some::Role', 'Some::Other::Role'
372 Composes role with package. See also L<Role::Tiny::With>.
374 =head2 apply_roles_to_object
376 Role::Tiny->apply_roles_to_object($foo, qw(Some::Role1 Some::Role2));
378 Composes roles in order into object directly. Object is reblessed into the
381 =head2 create_class_with_roles
383 Role::Tiny->create_class_with_roles('Some::Base', qw(Some::Role1 Some::Role2));
385 Creates a new class based on base, with the roles composed into it in order.
386 New class is returned.
392 if (Role::Tiny::does_role($foo, 'Some::Role')) {
396 Returns true if class has been composed with role.
398 This subroutine is also installed as ->does on any class a Role::Tiny is
399 composed into unless that class already has an ->does method, so
401 if ($foo->does('Some::Role')) {
405 will work for classes but to test a role, one must use ::does_role directly
407 =head1 IMPORTED SUBROUTINES
411 requires qw(foo bar);
413 Declares a list of methods that must be defined to compose role.
419 with 'Some::Role1', 'Some::Role2';
421 Composes another role into the current role (or class via L<Role::Tiny::With>).
423 If you have conflicts and want to resolve them in favour of Some::Role1 you
429 If you have conflicts and want to resolve different conflicts in favour of
430 different roles, please refactor your codebase.
434 before foo => sub { ... };
436 See L<< Class::Method::Modifiers/before method(s) => sub { ... } >> for full
439 Note that since you are not required to use method modifiers,
440 L<Class::Method::Modifiers> is lazily loaded and we do not declare it as
441 a dependency. If your L<Role::Tiny> role uses modifiers you must depend on
442 both L<Class::Method::Modifiers> and L<Role::Tiny>.
446 around foo => sub { ... };
448 See L<< Class::Method::Modifiers/around method(s) => sub { ... } >> for full
451 Note that since you are not required to use method modifiers,
452 L<Class::Method::Modifiers> is lazily loaded and we do not declare it as
453 a dependency. If your L<Role::Tiny> role uses modifiers you must depend on
454 both L<Class::Method::Modifiers> and L<Role::Tiny>.
458 after foo => sub { ... };
460 See L<< Class::Method::Modifiers/after method(s) => sub { ... } >> for full
463 Note that since you are not required to use method modifiers,
464 L<Class::Method::Modifiers> is lazily loaded and we do not declare it as
465 a dependency. If your L<Role::Tiny> role uses modifiers you must depend on
466 both L<Class::Method::Modifiers> and L<Role::Tiny>.
470 L<Role::Tiny> is the attribute-less subset of L<Moo::Role>; L<Moo::Role> is
471 a meta-protocol-less subset of the king of role systems, L<Moose::Role>.
473 If you don't want method modifiers and do want to be forcibly restricted
474 to a single role application per class, Ovid's L<Role::Basic> exists. But
475 Stevan Little (the L<Moose> author) don't find the additional restrictions
476 to be amazingly helpful in most cases; L<Role::Basic>'s choices are more
477 a guide to what you should prefer doing, to our mind, rather than something
478 that needs to be enforced.
482 mst - Matt S. Trout (cpan:MSTROUT) <mst@shadowcat.co.uk>
486 dg - David Leadbeater (cpan:DGL) <dgl@dgl.cx>
488 frew - Arthur Axel "fREW" Schmidt (cpan:FREW) <frioux@gmail.com>
490 hobbs - Andrew Rodland (cpan:ARODLAND) <arodland@cpan.org>
492 jnap - John Napiorkowski (cpan:JJNAPIORK) <jjn1056@yahoo.com>
494 ribasushi - Peter Rabbitson (cpan:RIBASUSHI) <ribasushi@cpan.org>
496 chip - Chip Salzenberg (cpan:CHIPS) <chip@pobox.com>
498 ajgb - Alex J. G. BurzyĆski (cpan:AJGB) <ajgb@cpan.org>
500 doy - Jesse Luehrs (cpan:DOY) <doy at tozt dot net>
502 perigrin - Chris Prather (cpan:PERIGRIN) <chris@prather.org>
506 Copyright (c) 2010-2012 the Role::Tiny L</AUTHOR> and L</CONTRIBUTORS>
511 This library is free software and may be distributed under the same terms