3 sub _getglob { \*{$_[0]} }
4 sub _getstash { \%{"$_[0]::"} }
7 use warnings FATAL => 'all';
9 our $VERSION = '1.003002';
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 $me->is_role($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} = { $target => undef };
76 sub role_application_steps {
77 qw(_install_methods _check_requires _install_modifiers _copy_applied_list);
80 sub apply_single_role_to_package {
81 my ($me, $to, $role) = @_;
85 die "This is apply_role_to_package" if ref($to);
86 die "${role} is not a Role::Tiny" unless $me->is_role($role);
88 foreach my $step ($me->role_application_steps) {
89 $me->$step($to, $role);
93 sub _copy_applied_list {
94 my ($me, $to, $role) = @_;
95 # copy our role list into the target's
96 @{$APPLIED_TO{$to}||={}}{keys %{$APPLIED_TO{$role}}} = ();
99 sub apply_roles_to_object {
100 my ($me, $object, @roles) = @_;
101 die "No roles supplied!" unless @roles;
102 my $class = ref($object);
103 # on perl < 5.8.9, magic isn't copied to all ref copies. bless the parameter
104 # directly, so at least the variable passed to us will get any magic applied
105 bless($_[1], $me->create_class_with_roles($class, @roles));
108 my $role_suffix = 'A000';
109 sub _composite_name {
110 my ($me, $superclass, @roles) = @_;
113 '__WITH__', $superclass, my $compose_name = join '__AND__', @roles
116 if (length($new_name) > 252) {
117 $new_name = $COMPOSED{abbrev}{$new_name}
118 ||= substr($new_name, 0, 250 - length $role_suffix).'__'.$role_suffix++;
120 return wantarray ? ($new_name, $compose_name) : $new_name;
123 sub create_class_with_roles {
124 my ($me, $superclass, @roles) = @_;
126 die "No roles supplied!" unless @roles;
128 _load_module($superclass);
131 $seen{$_}++ for @roles;
132 if (my @dupes = grep $seen{$_} > 1, @roles) {
133 die "Duplicated roles: ".join(', ', @dupes);
137 my ($new_name, $compose_name) = $me->_composite_name($superclass, @roles);
139 return $new_name if $COMPOSED{class}{$new_name};
141 foreach my $role (@roles) {
143 die "${role} is not a Role::Tiny" unless $me->is_role($role);
152 my $composite_info = $me->_composite_info_for(@roles);
153 my %conflicts = %{$composite_info->{conflicts}};
154 if (keys %conflicts) {
158 "Method name conflict for '$_' between roles "
159 ."'".join(' and ', sort values %{$conflicts{$_}})."'"
160 .", cannot apply these simultaneously to an object."
165 my @composable = map $me->_composable_package_for($_), reverse @roles;
167 # some methods may not exist in the role, but get generated by
168 # _composable_package_for (Moose accessors via Moo). filter out anything
169 # provided by the composable packages, excluding the subs we generated to
170 # make modifiers work.
171 my @requires = grep {
173 !grep $_->can($method) && !$COMPOSED{role}{$_}{modifiers_only}{$method},
175 } @{$composite_info->{requires}};
177 $me->_check_requires(
178 $superclass, $compose_name, \@requires
181 *{_getglob("${new_name}::ISA")} = [ @composable, $superclass ];
183 @{$APPLIED_TO{$new_name}||={}}{
184 map keys %{$APPLIED_TO{$_}}, @roles
187 $COMPOSED{class}{$new_name} = 1;
191 # preserved for compat, and apply_roles_to_package calls it to allow an
192 # updated Role::Tiny to use a non-updated Moo::Role
194 sub apply_role_to_package { shift->apply_single_role_to_package(@_) }
196 sub apply_roles_to_package {
197 my ($me, $to, @roles) = @_;
199 return $me->apply_role_to_package($to, $roles[0]) if @roles == 1;
201 my %conflicts = %{$me->_composite_info_for(@roles)->{conflicts}};
202 my @have = grep $to->can($_), keys %conflicts;
203 delete @conflicts{@have};
205 if (keys %conflicts) {
209 "Due to a method name conflict between roles "
210 ."'".join(' and ', sort values %{$conflicts{$_}})."'"
211 .", the method '$_' must be implemented by '${to}'"
216 # conflicting methods are supposed to be treated as required by the
217 # composed role. we don't have an actual composed role, but because
218 # we know the target class already provides them, we can instead
219 # pretend that the roles don't do for the duration of application.
220 my @role_methods = map $me->_concrete_methods_of($_), @roles;
221 # separate loops, since local ..., delete ... for ...; creates a scope
222 local @{$_}{@have} for @role_methods;
223 delete @{$_}{@have} for @role_methods;
225 # the if guard here is essential since otherwise we accidentally create
226 # a $INFO for something that isn't a Role::Tiny (or Moo::Role) because
227 # autovivification hates us and wants us to die()
229 delete $INFO{$to}{methods}; # reset since we're about to add methods
232 # backcompat: allow subclasses to use apply_single_role_to_package
233 # to apply changes. set a local var so ours does nothing.
234 our %BACKCOMPAT_HACK;
235 if($me ne __PACKAGE__
236 and exists $BACKCOMPAT_HACK{$me} ? $BACKCOMPAT_HACK{$me} :
237 $BACKCOMPAT_HACK{$me} =
238 $me->can('role_application_steps')
239 == \&role_application_steps
240 && $me->can('apply_single_role_to_package')
241 != \&apply_single_role_to_package
243 foreach my $role (@roles) {
244 $me->apply_single_role_to_package($to, $role);
248 foreach my $step ($me->role_application_steps) {
249 foreach my $role (@roles) {
250 $me->$step($to, $role);
254 $APPLIED_TO{$to}{join('|',@roles)} = 1;
257 sub _composite_info_for {
258 my ($me, @roles) = @_;
259 $COMPOSITE_INFO{join('|', sort @roles)} ||= do {
260 foreach my $role (@roles) {
264 foreach my $role (@roles) {
265 my $this_methods = $me->_concrete_methods_of($role);
266 $methods{$_}{$this_methods->{$_}} = $role for keys %$this_methods;
269 @requires{map @{$INFO{$_}{requires}||[]}, @roles} = ();
270 delete $requires{$_} for keys %methods;
271 delete $methods{$_} for grep keys(%{$methods{$_}}) == 1, keys %methods;
272 +{ conflicts => \%methods, requires => [keys %requires] }
276 sub _composable_package_for {
277 my ($me, $role) = @_;
278 my $composed_name = 'Role::Tiny::_COMPOSABLE::'.$role;
279 return $composed_name if $COMPOSED{role}{$composed_name};
280 $me->_install_methods($composed_name, $role);
281 my $base_name = $composed_name.'::_BASE';
282 # force stash to exist so ->can doesn't complain
283 _getstash($base_name);
284 # Not using _getglob, since setting @ISA via the typeglob breaks
285 # inheritance on 5.10.0 if the stash has previously been accessed an
286 # then a method called on the class (in that order!), which
287 # ->_install_methods (with the help of ->_install_does) ends up doing.
288 { no strict 'refs'; @{"${composed_name}::ISA"} = ( $base_name ); }
289 my $modifiers = $INFO{$role}{modifiers}||[];
291 my @modifiers = grep !$composed_name->can($_),
292 do { my %h; @h{map @{$_}[1..$#$_-1], @$modifiers} = (); keys %h };
293 foreach my $modified (@modifiers) {
294 push @mod_base, "sub ${modified} { shift->next::method(\@_) }";
299 eval(my $code = join "\n", "package ${base_name};", @mod_base);
300 $e = "Evaling failed: $@\nTrying to eval:\n${code}" if $@;
303 $me->_install_modifiers($composed_name, $role);
304 $COMPOSED{role}{$composed_name} = {
305 modifiers_only => { map { $_ => 1 } @modifiers },
307 return $composed_name;
310 sub _check_requires {
311 my ($me, $to, $name, $requires) = @_;
312 return unless my @requires = @{$requires||$INFO{$name}{requires}||[]};
313 if (my @requires_fail = grep !$to->can($_), @requires) {
314 # role -> role, add to requires, role -> class, error out
315 if (my $to_info = $INFO{$to}) {
316 push @{$to_info->{requires}||=[]}, @requires_fail;
318 die "Can't apply ${name} to ${to} - missing ".join(', ', @requires_fail);
323 sub _concrete_methods_of {
324 my ($me, $role) = @_;
325 my $info = $INFO{$role};
326 # grab role symbol table
327 my $stash = _getstash($role);
328 # reverse so our keys become the values (captured coderefs) in case
329 # they got copied or re-used since
330 my $not_methods = { reverse %{$info->{not_methods}||{}} };
331 $info->{methods} ||= +{
332 # grab all code entries that aren't in the not_methods list
334 my $code = *{$stash->{$_}}{CODE};
335 ( ! $code or exists $not_methods->{$code} ) ? () : ($_ => $code)
336 } grep !ref($stash->{$_}), keys %$stash
340 sub methods_provided_by {
341 my ($me, $role) = @_;
342 die "${role} is not a Role::Tiny" unless $me->is_role($role);
343 (keys %{$me->_concrete_methods_of($role)}, @{$INFO{$role}->{requires}||[]});
346 sub _install_methods {
347 my ($me, $to, $role) = @_;
349 my $info = $INFO{$role};
351 my $methods = $me->_concrete_methods_of($role);
353 # grab target symbol table
354 my $stash = _getstash($to);
356 # determine already extant methods of target
359 +(ref($stash->{$_}) || *{$stash->{$_}}{CODE}),
363 foreach my $i (grep !exists $has_methods{$_}, keys %$methods) {
365 my $glob = _getglob "${to}::${i}";
366 *$glob = $methods->{$i};
368 # overloads using method names have the method stored in the scalar slot
369 # and &overload::nil in the code slot.
372 && defined &overload::nil
373 && $methods->{$i} == \&overload::nil;
375 my $overload = ${ *{_getglob "${role}::${i}"}{SCALAR} };
377 unless defined $overload;
382 $me->_install_does($to);
385 sub _install_modifiers {
386 my ($me, $to, $name) = @_;
387 return unless my $modifiers = $INFO{$name}{modifiers};
388 if (my $info = $INFO{$to}) {
389 push @{$info->{modifiers}}, @{$modifiers||[]};
391 foreach my $modifier (@{$modifiers||[]}) {
392 $me->_install_single_modifier($to, @$modifier);
399 sub _install_single_modifier {
400 my ($me, @args) = @_;
401 defined($vcheck_error) or $vcheck_error = do {
403 eval { Class::Method::Modifiers->VERSION(1.05); 1 }
407 $vcheck_error and die $vcheck_error;
408 Class::Method::Modifiers::install_modifier(@args);
411 my $FALLBACK = sub { 0 };
415 # only add does() method to classes
416 return if $me->is_role($to);
418 # add does() only if they don't have one
419 *{_getglob "${to}::does"} = \&does_role unless $to->can('does');
422 if $to->can('DOES') and $to->can('DOES') != (UNIVERSAL->can('DOES') || 0);
424 my $existing = $to->can('DOES') || $to->can('isa') || $FALLBACK;
426 my ($proto, $role) = @_;
427 Role::Tiny::does_role($proto, $role) or $proto->$existing($role);
429 no warnings 'redefine';
430 *{_getglob "${to}::DOES"} = $new_sub;
434 my ($proto, $role) = @_;
440 foreach my $class (@{mro::get_linear_isa(ref($proto)||$proto)}) {
441 return 1 if exists $APPLIED_TO{$class}{$role};
447 my ($me, $role) = @_;
448 return !!($INFO{$role} && $INFO{$role}{is_role});
457 Role::Tiny - Roles. Like a nouvelle cuisine portion size slice of Moose.
469 around baz => sub { ... }
477 use Role::Tiny::With;
479 # bar gets imported, but not foo
484 # baz is wrapped in the around modifier by Class::Method::Modifiers
489 If you wanted attributes as well, look at L<Moo::Role>.
493 C<Role::Tiny> is a minimalist role composition tool.
495 =head1 ROLE COMPOSITION
497 Role composition can be thought of as much more clever and meaningful multiple
498 inheritance. The basics of this implementation of roles is:
504 If a method is already defined on a class, that method will not be composed in
509 If a method that the role L</requires> to be implemented is not implemented,
510 role application will fail loudly.
514 Unlike L<Class::C3>, where the B<last> class inherited from "wins," role
515 composition is the other way around, where the class wins. If multiple roles
516 are applied in a single call (single with statement), then if any of their
517 provided methods clash, an exception is raised unless the class provides
518 a method since this conflict indicates a potential problem.
520 =head1 IMPORTED SUBROUTINES
524 requires qw(foo bar);
526 Declares a list of methods that must be defined to compose role.
532 with 'Some::Role1', 'Some::Role2';
534 Composes another role into the current role (or class via L<Role::Tiny::With>).
536 If you have conflicts and want to resolve them in favour of Some::Role1 you
542 If you have conflicts and want to resolve different conflicts in favour of
543 different roles, please refactor your codebase.
547 before foo => sub { ... };
549 See L<< Class::Method::Modifiers/before method(s) => sub { ... } >> for full
552 Note that since you are not required to use method modifiers,
553 L<Class::Method::Modifiers> is lazily loaded and we do not declare it as
554 a dependency. If your L<Role::Tiny> role uses modifiers you must depend on
555 both L<Class::Method::Modifiers> and L<Role::Tiny>.
559 around foo => sub { ... };
561 See L<< Class::Method::Modifiers/around method(s) => sub { ... } >> for full
564 Note that since you are not required to use method modifiers,
565 L<Class::Method::Modifiers> is lazily loaded and we do not declare it as
566 a dependency. If your L<Role::Tiny> role uses modifiers you must depend on
567 both L<Class::Method::Modifiers> and L<Role::Tiny>.
571 after foo => sub { ... };
573 See L<< Class::Method::Modifiers/after method(s) => sub { ... } >> for full
576 Note that since you are not required to use method modifiers,
577 L<Class::Method::Modifiers> is lazily loaded and we do not declare it as
578 a dependency. If your L<Role::Tiny> role uses modifiers you must depend on
579 both L<Class::Method::Modifiers> and L<Role::Tiny>.
581 =head2 Strict and Warnings
583 In addition to importing subroutines, using C<Role::Tiny> applies L<strict> and
584 L<fatal warnings|perllexwarn/Fatal Warnings> to the caller. It's possible to
585 disable these if desired:
588 use warnings NONFATAL => 'all';
594 if (Role::Tiny::does_role($foo, 'Some::Role')) {
598 Returns true if class has been composed with role.
600 This subroutine is also installed as ->does on any class a Role::Tiny is
601 composed into unless that class already has an ->does method, so
603 if ($foo->does('Some::Role')) {
607 will work for classes but to test a role, one must use ::does_role directly.
609 Additionally, Role::Tiny will override the standard Perl C<DOES> method
610 for your class. However, if C<any> class in your class' inheritance
611 hierarchy provides C<DOES>, then Role::Tiny will not override it.
615 =head2 apply_roles_to_package
617 Role::Tiny->apply_roles_to_package(
618 'Some::Package', 'Some::Role', 'Some::Other::Role'
621 Composes role with package. See also L<Role::Tiny::With>.
623 =head2 apply_roles_to_object
625 Role::Tiny->apply_roles_to_object($foo, qw(Some::Role1 Some::Role2));
627 Composes roles in order into object directly. Object is reblessed into the
630 =head2 create_class_with_roles
632 Role::Tiny->create_class_with_roles('Some::Base', qw(Some::Role1 Some::Role2));
634 Creates a new class based on base, with the roles composed into it in order.
635 New class is returned.
639 Role::Tiny->is_role('Some::Role1')
641 Returns true if the given package is a role.
647 =item * On perl 5.8.8 and earlier, applying a role to an object won't apply any
648 overloads from the role to all copies of the object.
652 L<Role::Tiny> is the attribute-less subset of L<Moo::Role>; L<Moo::Role> is
653 a meta-protocol-less subset of the king of role systems, L<Moose::Role>.
655 If you don't want method modifiers and do want to be forcibly restricted
656 to a single role application per class, Ovid's L<Role::Basic> exists. But
657 Stevan Little (the L<Moose> author) and I don't find the additional
658 restrictions to be amazingly helpful in most cases; L<Role::Basic>'s choices
659 are more a guide to what you should prefer doing, to our mind, rather than
660 something that needs to be enforced.
664 mst - Matt S. Trout (cpan:MSTROUT) <mst@shadowcat.co.uk>
668 dg - David Leadbeater (cpan:DGL) <dgl@dgl.cx>
670 frew - Arthur Axel "fREW" Schmidt (cpan:FREW) <frioux@gmail.com>
672 hobbs - Andrew Rodland (cpan:ARODLAND) <arodland@cpan.org>
674 jnap - John Napiorkowski (cpan:JJNAPIORK) <jjn1056@yahoo.com>
676 ribasushi - Peter Rabbitson (cpan:RIBASUSHI) <ribasushi@cpan.org>
678 chip - Chip Salzenberg (cpan:CHIPS) <chip@pobox.com>
680 ajgb - Alex J. G. Burzyński (cpan:AJGB) <ajgb@cpan.org>
682 doy - Jesse Luehrs (cpan:DOY) <doy at tozt dot net>
684 perigrin - Chris Prather (cpan:PERIGRIN) <chris@prather.org>
686 Mithaldu - Christian Walde (cpan:MITHALDU) <walde.christian@googlemail.com>
688 ilmari - Dagfinn Ilmari Mannsåker (cpan:ILMARI) <ilmari@ilmari.org>
690 tobyink - Toby Inkster (cpan:TOBYINK) <tobyink@cpan.org>
692 haarg - Graham Knop (cpan:HAARG) <haarg@haarg.org>
696 Copyright (c) 2010-2012 the Role::Tiny L</AUTHOR> and L</CONTRIBUTORS>
701 This library is free software and may be distributed under the same terms