3 sub _getglob { \*{$_[0]} }
4 sub _getstash { \%{"$_[0]::"} }
7 use warnings FATAL => 'all';
9 our $VERSION = '1.002005'; # 1.2.5
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 $INFO{$target}{is_role} = 1;
48 # get symbol table reference
49 my $stash = _getstash($target);
50 # install before/after/around subs
51 foreach my $type (qw(before after around)) {
52 *{_getglob "${target}::${type}"} = sub {
53 require Class::Method::Modifiers;
54 push @{$INFO{$target}{modifiers}||=[]}, [ $type => @_ ];
58 *{_getglob "${target}::requires"} = sub {
59 push @{$INFO{$target}{requires}||=[]}, @_;
62 *{_getglob "${target}::with"} = sub {
63 $me->apply_roles_to_package($target, @_);
66 # grab all *non-constant* (stash slot is not a scalarref) subs present
67 # in the symbol table and store their refaddrs (no need to forcibly
68 # inflate constant subs into real subs) with a map to the coderefs in
69 # case of copying or re-use
70 my @not_methods = (map { *$_{CODE}||() } grep !ref($_), values %$stash);
71 @{$INFO{$target}{not_methods}={}}{@not_methods} = @not_methods;
73 $APPLIED_TO{$target} = { $target => undef };
76 sub role_application_steps {
77 qw(_install_methods _install_modifiers _check_requires _copy_applied_list);
80 sub apply_single_role_to_package {
81 my ($me, $to, $role) = @_;
82 return if our $SKIP_APPLY;
86 die "This is apply_role_to_package" if ref($to);
87 die "${role} is not a Role::Tiny" unless $INFO{$role};
89 foreach my $step ($me->role_application_steps) {
90 $me->$step($to, $role);
94 sub _copy_applied_list {
95 my ($me, $to, $role) = @_;
96 # copy our role list into the target's
97 @{$APPLIED_TO{$to}||={}}{keys %{$APPLIED_TO{$role}}} = ();
100 sub apply_roles_to_object {
101 my ($me, $object, @roles) = @_;
102 die "No roles supplied!" unless @roles;
103 my $class = ref($object);
104 bless($object, $me->create_class_with_roles($class, @roles));
108 sub create_class_with_roles {
109 my ($me, $superclass, @roles) = @_;
111 die "No roles supplied!" unless @roles;
113 _load_module($superclass);
116 $seen{$_}++ for @roles;
117 if (my @dupes = grep $seen{$_} > 1, @roles) {
118 die "Duplicated roles: ".join(', ', @dupes);
123 '__WITH__', $superclass, my $compose_name = join '__AND__', @roles
126 return $new_name if $COMPOSED{class}{$new_name};
128 foreach my $role (@roles) {
130 die "${role} is not a Role::Tiny" unless $INFO{$role};
139 my %conflicts = %{$me->_composite_info_for(@roles)->{conflicts}};
140 if (keys %conflicts) {
144 "Method name conflict for '$_' between roles "
145 ."'".join(' and ', sort values %{$conflicts{$_}})."'"
146 .", cannot apply these simultaneously to an object."
151 my @composable = map $me->_composable_package_for($_), reverse @roles;
153 *{_getglob("${new_name}::ISA")} = [ @composable, $superclass ];
155 my @info = map $INFO{$_}, @roles;
157 $me->_check_requires(
158 $new_name, $compose_name,
159 do { my %h; @h{map @{$_->{requires}||[]}, @info} = (); keys %h }
162 @{$APPLIED_TO{$new_name}||={}}{
163 map keys %{$APPLIED_TO{$_}}, @roles
166 $COMPOSED{class}{$new_name} = 1;
170 # preserved for compat, and apply_roles_to_package calls it to allow an
171 # updated Role::Tiny to use a non-updated Moo::Role
173 sub apply_role_to_package { shift->apply_single_role_to_package(@_) }
175 sub apply_roles_to_package {
176 my ($me, $to, @roles) = @_;
178 return $me->apply_role_to_package($to, $roles[0]) if @roles == 1;
180 my %conflicts = %{$me->_composite_info_for(@roles)->{conflicts}};
181 delete $conflicts{$_} for keys %{ $me->_concrete_methods_of($to) };
182 if (keys %conflicts) {
186 "Due to a method name conflict between roles "
187 ."'".join(' and ', sort values %{$conflicts{$_}})."'"
188 .", the method '$_' must be implemented by '${to}'"
193 # the if guard here is essential since otherwise we accidentally create
194 # a $INFO for something that isn't a Role::Tiny (or Moo::Role) because
195 # autovivification hates us and wants us to die()
197 delete $INFO{$to}{methods}; # reset since we're about to add methods
199 foreach my $step ($me->role_application_steps) {
200 foreach my $role (@roles) {
201 $me->$step($to, $role);
204 if ($me ne __PACKAGE__
205 and $me->can('apply_single_role_to_package')
206 != \&apply_single_role_to_package) {
207 # backcompat: allow subclasses to use apply_single_role_to_package
208 # to apply changes. set a local var so ours does nothing.
209 local our $SKIP_APPLY = 1;
210 foreach my $role (@roles) {
211 $me->apply_single_role_to_package($to, $role);
214 $APPLIED_TO{$to}{join('|',@roles)} = 1;
217 sub _composite_info_for {
218 my ($me, @roles) = @_;
219 $COMPOSITE_INFO{join('|', sort @roles)} ||= do {
220 foreach my $role (@roles) {
224 foreach my $role (@roles) {
225 my $this_methods = $me->_concrete_methods_of($role);
226 $methods{$_}{$this_methods->{$_}} = $role for keys %$this_methods;
228 delete $methods{$_} for grep keys(%{$methods{$_}}) == 1, keys %methods;
229 +{ conflicts => \%methods }
233 sub _composable_package_for {
234 my ($me, $role) = @_;
235 my $composed_name = 'Role::Tiny::_COMPOSABLE::'.$role;
236 return $composed_name if $COMPOSED{role}{$composed_name};
237 $me->_install_methods($composed_name, $role);
238 my $base_name = $composed_name.'::_BASE';
239 # Not using _getglob, since setting @ISA via the typeglob breaks
240 # inheritance on 5.10.0 if the stash has previously been accessed an
241 # then a method called on the class (in that order!), which
242 # ->_install_methods (with the help of ->_install_does) ends up doing.
243 { no strict 'refs'; @{"${composed_name}::ISA"} = ( $base_name ); }
244 my $modifiers = $INFO{$role}{modifiers}||[];
246 foreach my $modified (
247 do { my %h; @h{map $_->[1], @$modifiers} = (); keys %h }
249 push @mod_base, "sub ${modified} { shift->next::method(\@_) }";
254 eval(my $code = join "\n", "package ${base_name};", @mod_base);
255 $e = "Evaling failed: $@\nTrying to eval:\n${code}" if $@;
258 $me->_install_modifiers($composed_name, $role);
259 $COMPOSED{role}{$composed_name} = 1;
260 return $composed_name;
263 sub _check_requires {
264 my ($me, $to, $name) = @_;
265 return unless my @requires = @{$INFO{$name}{requires}||[]};
266 if (my @requires_fail = grep !$to->can($_), @requires) {
267 # role -> role, add to requires, role -> class, error out
268 if (my $to_info = $INFO{$to}) {
269 push @{$to_info->{requires}||=[]}, @requires_fail;
271 die "Can't apply ${name} to ${to} - missing ".join(', ', @requires_fail);
276 sub _concrete_methods_of {
277 my ($me, $role) = @_;
278 my $info = $INFO{$role};
279 # grab role symbol table
280 my $stash = _getstash($role);
281 # reverse so our keys become the values (captured coderefs) in case
282 # they got copied or re-used since
283 my $not_methods = { reverse %{$info->{not_methods}||{}} };
284 $info->{methods} ||= +{
285 # grab all code entries that aren't in the not_methods list
287 my $code = *{$stash->{$_}}{CODE};
288 ( ! $code or exists $not_methods->{$code} ) ? () : ($_ => $code)
289 } grep !ref($stash->{$_}), keys %$stash
293 sub methods_provided_by {
294 my ($me, $role) = @_;
295 die "${role} is not a Role::Tiny" unless my $info = $INFO{$role};
296 (keys %{$me->_concrete_methods_of($role)}, @{$info->{requires}||[]});
299 sub _install_methods {
300 my ($me, $to, $role) = @_;
302 my $info = $INFO{$role};
304 my $methods = $me->_concrete_methods_of($role);
306 # grab target symbol table
307 my $stash = _getstash($to);
309 # determine already extant methods of target
312 +(ref($stash->{$_}) || *{$stash->{$_}}{CODE}),
316 foreach my $i (grep !exists $has_methods{$_}, keys %$methods) {
318 *{_getglob "${to}::${i}"} = $methods->{$i};
321 $me->_install_does($to);
324 sub _install_modifiers {
325 my ($me, $to, $name) = @_;
326 return unless my $modifiers = $INFO{$name}{modifiers};
327 if (my $info = $INFO{$to}) {
328 push @{$info->{modifiers}}, @{$modifiers||[]};
330 foreach my $modifier (@{$modifiers||[]}) {
331 $me->_install_single_modifier($to, @$modifier);
338 sub _install_single_modifier {
339 my ($me, @args) = @_;
340 defined($vcheck_error) or $vcheck_error = do {
342 eval { Class::Method::Modifiers->VERSION(1.05); 1 }
346 $vcheck_error and die $vcheck_error;
347 Class::Method::Modifiers::install_modifier(@args);
350 my $FALLBACK = sub { 0 };
354 # only add does() method to classes
355 return if $INFO{$to};
357 # add does() only if they don't have one
358 *{_getglob "${to}::does"} = \&does_role unless $to->can('does');
360 return if ($to->can('DOES') and $to->can('DOES') != (UNIVERSAL->can('DOES') || 0));
362 my $existing = $to->can('DOES') || $to->can('isa') || $FALLBACK;
364 my ($proto, $role) = @_;
365 Role::Tiny::does_role($proto, $role) or $proto->$existing($role);
367 no warnings 'redefine';
368 *{_getglob "${to}::DOES"} = $new_sub;
372 my ($proto, $role) = @_;
378 foreach my $class (@{mro::get_linear_isa(ref($proto)||$proto)}) {
379 return 1 if exists $APPLIED_TO{$class}{$role};
385 my ($me, $role) = @_;
386 return !!$INFO{$role};
395 Role::Tiny - Roles. Like a nouvelle cuisine portion size slice of Moose.
407 around baz => sub { ... }
415 use Role::Tiny::With;
417 # bar gets imported, but not foo
422 # baz is wrapped in the around modifier by Class::Method::Modifiers
427 If you wanted attributes as well, look at L<Moo::Role>.
431 C<Role::Tiny> is a minimalist role composition tool.
433 =head1 ROLE COMPOSITION
435 Role composition can be thought of as much more clever and meaningful multiple
436 inheritance. The basics of this implementation of roles is:
442 If a method is already defined on a class, that method will not be composed in
447 If a method that the role L</requires> to be implemented is not implemented,
448 role application will fail loudly.
452 Unlike L<Class::C3>, where the B<last> class inherited from "wins," role
453 composition is the other way around, where the class wins. If multiple roles
454 are applied in a single call (single with statement), then if any of their
455 provided methods clash, an exception is raised unless the class provides
456 a method since this conflict indicates a potential problem.
458 =head1 IMPORTED SUBROUTINES
462 requires qw(foo bar);
464 Declares a list of methods that must be defined to compose role.
470 with 'Some::Role1', 'Some::Role2';
472 Composes another role into the current role (or class via L<Role::Tiny::With>).
474 If you have conflicts and want to resolve them in favour of Some::Role1 you
480 If you have conflicts and want to resolve different conflicts in favour of
481 different roles, please refactor your codebase.
485 before foo => sub { ... };
487 See L<< Class::Method::Modifiers/before method(s) => sub { ... } >> for full
490 Note that since you are not required to use method modifiers,
491 L<Class::Method::Modifiers> is lazily loaded and we do not declare it as
492 a dependency. If your L<Role::Tiny> role uses modifiers you must depend on
493 both L<Class::Method::Modifiers> and L<Role::Tiny>.
497 around foo => sub { ... };
499 See L<< Class::Method::Modifiers/around method(s) => sub { ... } >> for full
502 Note that since you are not required to use method modifiers,
503 L<Class::Method::Modifiers> is lazily loaded and we do not declare it as
504 a dependency. If your L<Role::Tiny> role uses modifiers you must depend on
505 both L<Class::Method::Modifiers> and L<Role::Tiny>.
509 after foo => sub { ... };
511 See L<< Class::Method::Modifiers/after method(s) => sub { ... } >> for full
514 Note that since you are not required to use method modifiers,
515 L<Class::Method::Modifiers> is lazily loaded and we do not declare it as
516 a dependency. If your L<Role::Tiny> role uses modifiers you must depend on
517 both L<Class::Method::Modifiers> and L<Role::Tiny>.
523 if (Role::Tiny::does_role($foo, 'Some::Role')) {
527 Returns true if class has been composed with role.
529 This subroutine is also installed as ->does on any class a Role::Tiny is
530 composed into unless that class already has an ->does method, so
532 if ($foo->does('Some::Role')) {
536 will work for classes but to test a role, one must use ::does_role directly.
538 Additionally, Role::Tiny will override the standard Perl C<DOES> method
539 for your class. However, if C<any> class in your class' inheritance
540 hierarchy provides C<DOES>, then Role::Tiny will not override it.
544 =head2 apply_roles_to_package
546 Role::Tiny->apply_roles_to_package(
547 'Some::Package', 'Some::Role', 'Some::Other::Role'
550 Composes role with package. See also L<Role::Tiny::With>.
552 =head2 apply_roles_to_object
554 Role::Tiny->apply_roles_to_object($foo, qw(Some::Role1 Some::Role2));
556 Composes roles in order into object directly. Object is reblessed into the
559 =head2 create_class_with_roles
561 Role::Tiny->create_class_with_roles('Some::Base', qw(Some::Role1 Some::Role2));
563 Creates a new class based on base, with the roles composed into it in order.
564 New class is returned.
568 Role::Tiny->is_role('Some::Role1')
570 Returns true if the given package is a role.
574 L<Role::Tiny> is the attribute-less subset of L<Moo::Role>; L<Moo::Role> is
575 a meta-protocol-less subset of the king of role systems, L<Moose::Role>.
577 If you don't want method modifiers and do want to be forcibly restricted
578 to a single role application per class, Ovid's L<Role::Basic> exists. But
579 Stevan Little (the L<Moose> author) and I don't find the additional
580 restrictions to be amazingly helpful in most cases; L<Role::Basic>'s choices
581 are more a guide to what you should prefer doing, to our mind, rather than
582 something that needs to be enforced.
586 mst - Matt S. Trout (cpan:MSTROUT) <mst@shadowcat.co.uk>
590 dg - David Leadbeater (cpan:DGL) <dgl@dgl.cx>
592 frew - Arthur Axel "fREW" Schmidt (cpan:FREW) <frioux@gmail.com>
594 hobbs - Andrew Rodland (cpan:ARODLAND) <arodland@cpan.org>
596 jnap - John Napiorkowski (cpan:JJNAPIORK) <jjn1056@yahoo.com>
598 ribasushi - Peter Rabbitson (cpan:RIBASUSHI) <ribasushi@cpan.org>
600 chip - Chip Salzenberg (cpan:CHIPS) <chip@pobox.com>
602 ajgb - Alex J. G. Burzyński (cpan:AJGB) <ajgb@cpan.org>
604 doy - Jesse Luehrs (cpan:DOY) <doy at tozt dot net>
606 perigrin - Chris Prather (cpan:PERIGRIN) <chris@prather.org>
608 Mithaldu - Christian Walde (cpan:MITHALDU) <walde.christian@googlemail.com>
610 ilmari - Dagfinn Ilmari Mannsåker (cpan:ILMARI) <ilmari@ilmari.org>
612 tobyink - Toby Inkster (cpan:TOBYINK) <tobyink@cpan.org>
616 Copyright (c) 2010-2012 the Role::Tiny L</AUTHOR> and L</CONTRIBUTORS>
621 This library is free software and may be distributed under the same terms