3 sub _getglob { \*{$_[0]} }
4 sub _getstash { \%{"$_[0]::"} }
7 use warnings FATAL => 'all';
9 our $VERSION = '1.003003';
10 $VERSION = eval $VERSION;
18 # Module state workaround totally stolen from Zefram's Module::Runtime.
21 *_WORK_AROUND_BROKEN_MODULE_STATE = "$]" < 5.009 ? sub(){1} : sub(){0};
22 *_MRO_MODULE = "$]" < 5.010 ? sub(){"MRO/Compat.pm"} : sub(){"mro.pm"};
25 sub Role::Tiny::__GUARD__::DESTROY {
26 delete $INC{$_[0]->[0]} if @{$_[0]};
30 (my $proto = $_[0]) =~ s/::/\//g;
32 return 1 if $INC{$proto};
33 # can't just ->can('can') because a sub-package Foo::Bar::Baz
34 # creates a 'Baz::' key in Foo::Bar's symbol table
35 return 1 if grep !/::$/, keys %{_getstash($_[0])||{}};
36 my $guard = _WORK_AROUND_BROKEN_MODULE_STATE
37 && bless([ $proto ], 'Role::Tiny::__GUARD__');
39 pop @$guard if _WORK_AROUND_BROKEN_MODULE_STATE;
47 warnings->import(FATAL => 'all');
48 return if $me->is_role($target); # already exported into this package
49 $INFO{$target}{is_role} = 1;
50 # get symbol table reference
51 my $stash = _getstash($target);
52 # install before/after/around subs
53 foreach my $type (qw(before after around)) {
54 *{_getglob "${target}::${type}"} = sub {
55 require Class::Method::Modifiers;
56 push @{$INFO{$target}{modifiers}||=[]}, [ $type => @_ ];
60 *{_getglob "${target}::requires"} = sub {
61 push @{$INFO{$target}{requires}||=[]}, @_;
64 *{_getglob "${target}::with"} = sub {
65 $me->apply_roles_to_package($target, @_);
68 # grab all *non-constant* (stash slot is not a scalarref) subs present
69 # in the symbol table and store their refaddrs (no need to forcibly
70 # inflate constant subs into real subs) with a map to the coderefs in
71 # case of copying or re-use
72 my @not_methods = (map { *$_{CODE}||() } grep !ref($_), values %$stash);
73 @{$INFO{$target}{not_methods}={}}{@not_methods} = @not_methods;
75 $APPLIED_TO{$target} = { $target => undef };
76 $_->($target) for @ON_ROLE_CREATE;
79 sub role_application_steps {
80 qw(_install_methods _check_requires _install_modifiers _copy_applied_list);
83 sub apply_single_role_to_package {
84 my ($me, $to, $role) = @_;
88 die "This is apply_role_to_package" if ref($to);
89 die "${role} is not a Role::Tiny" unless $me->is_role($role);
91 foreach my $step ($me->role_application_steps) {
92 $me->$step($to, $role);
96 sub _copy_applied_list {
97 my ($me, $to, $role) = @_;
98 # copy our role list into the target's
99 @{$APPLIED_TO{$to}||={}}{keys %{$APPLIED_TO{$role}}} = ();
102 sub apply_roles_to_object {
103 my ($me, $object, @roles) = @_;
104 die "No roles supplied!" unless @roles;
105 my $class = ref($object);
106 # on perl < 5.8.9, magic isn't copied to all ref copies. bless the parameter
107 # directly, so at least the variable passed to us will get any magic applied
108 bless($_[1], $me->create_class_with_roles($class, @roles));
111 my $role_suffix = 'A000';
112 sub _composite_name {
113 my ($me, $superclass, @roles) = @_;
116 '__WITH__', $superclass, my $compose_name = join '__AND__', @roles
119 if (length($new_name) > 252) {
120 $new_name = $COMPOSED{abbrev}{$new_name}
121 ||= substr($new_name, 0, 250 - length $role_suffix).'__'.$role_suffix++;
123 return wantarray ? ($new_name, $compose_name) : $new_name;
126 sub create_class_with_roles {
127 my ($me, $superclass, @roles) = @_;
129 die "No roles supplied!" unless @roles;
131 _load_module($superclass);
134 $seen{$_}++ for @roles;
135 if (my @dupes = grep $seen{$_} > 1, @roles) {
136 die "Duplicated roles: ".join(', ', @dupes);
140 my ($new_name, $compose_name) = $me->_composite_name($superclass, @roles);
142 return $new_name if $COMPOSED{class}{$new_name};
144 foreach my $role (@roles) {
146 die "${role} is not a Role::Tiny" unless $me->is_role($role);
149 require(_MRO_MODULE);
151 my $composite_info = $me->_composite_info_for(@roles);
152 my %conflicts = %{$composite_info->{conflicts}};
153 if (keys %conflicts) {
157 "Method name conflict for '$_' between roles "
158 ."'".join(' and ', sort values %{$conflicts{$_}})."'"
159 .", cannot apply these simultaneously to an object."
164 my @composable = map $me->_composable_package_for($_), reverse @roles;
166 # some methods may not exist in the role, but get generated by
167 # _composable_package_for (Moose accessors via Moo). filter out anything
168 # provided by the composable packages, excluding the subs we generated to
169 # make modifiers work.
170 my @requires = grep {
172 !grep $_->can($method) && !$COMPOSED{role}{$_}{modifiers_only}{$method},
174 } @{$composite_info->{requires}};
176 $me->_check_requires(
177 $superclass, $compose_name, \@requires
180 *{_getglob("${new_name}::ISA")} = [ @composable, $superclass ];
182 @{$APPLIED_TO{$new_name}||={}}{
183 map keys %{$APPLIED_TO{$_}}, @roles
186 $COMPOSED{class}{$new_name} = 1;
190 # preserved for compat, and apply_roles_to_package calls it to allow an
191 # updated Role::Tiny to use a non-updated Moo::Role
193 sub apply_role_to_package { shift->apply_single_role_to_package(@_) }
195 sub apply_roles_to_package {
196 my ($me, $to, @roles) = @_;
198 return $me->apply_role_to_package($to, $roles[0]) if @roles == 1;
200 my %conflicts = %{$me->_composite_info_for(@roles)->{conflicts}};
201 my @have = grep $to->can($_), keys %conflicts;
202 delete @conflicts{@have};
204 if (keys %conflicts) {
208 "Due to a method name conflict between roles "
209 ."'".join(' and ', sort values %{$conflicts{$_}})."'"
210 .", the method '$_' must be implemented by '${to}'"
215 # conflicting methods are supposed to be treated as required by the
216 # composed role. we don't have an actual composed role, but because
217 # we know the target class already provides them, we can instead
218 # pretend that the roles don't do for the duration of application.
219 my @role_methods = map $me->_concrete_methods_of($_), @roles;
220 # separate loops, since local ..., delete ... for ...; creates a scope
221 local @{$_}{@have} for @role_methods;
222 delete @{$_}{@have} for @role_methods;
224 # the if guard here is essential since otherwise we accidentally create
225 # a $INFO for something that isn't a Role::Tiny (or Moo::Role) because
226 # autovivification hates us and wants us to die()
228 delete $INFO{$to}{methods}; # reset since we're about to add methods
231 # backcompat: allow subclasses to use apply_single_role_to_package
232 # to apply changes. set a local var so ours does nothing.
233 our %BACKCOMPAT_HACK;
234 if($me ne __PACKAGE__
235 and exists $BACKCOMPAT_HACK{$me} ? $BACKCOMPAT_HACK{$me} :
236 $BACKCOMPAT_HACK{$me} =
237 $me->can('role_application_steps')
238 == \&role_application_steps
239 && $me->can('apply_single_role_to_package')
240 != \&apply_single_role_to_package
242 foreach my $role (@roles) {
243 $me->apply_single_role_to_package($to, $role);
247 foreach my $step ($me->role_application_steps) {
248 foreach my $role (@roles) {
249 $me->$step($to, $role);
253 $APPLIED_TO{$to}{join('|',@roles)} = 1;
256 sub _composite_info_for {
257 my ($me, @roles) = @_;
258 $COMPOSITE_INFO{join('|', sort @roles)} ||= do {
259 foreach my $role (@roles) {
263 foreach my $role (@roles) {
264 my $this_methods = $me->_concrete_methods_of($role);
265 $methods{$_}{$this_methods->{$_}} = $role for keys %$this_methods;
268 @requires{map @{$INFO{$_}{requires}||[]}, @roles} = ();
269 delete $requires{$_} for keys %methods;
270 delete $methods{$_} for grep keys(%{$methods{$_}}) == 1, keys %methods;
271 +{ conflicts => \%methods, requires => [keys %requires] }
275 sub _composable_package_for {
276 my ($me, $role) = @_;
277 my $composed_name = 'Role::Tiny::_COMPOSABLE::'.$role;
278 return $composed_name if $COMPOSED{role}{$composed_name};
279 $me->_install_methods($composed_name, $role);
280 my $base_name = $composed_name.'::_BASE';
281 # force stash to exist so ->can doesn't complain
282 _getstash($base_name);
283 # Not using _getglob, since setting @ISA via the typeglob breaks
284 # inheritance on 5.10.0 if the stash has previously been accessed an
285 # then a method called on the class (in that order!), which
286 # ->_install_methods (with the help of ->_install_does) ends up doing.
287 { no strict 'refs'; @{"${composed_name}::ISA"} = ( $base_name ); }
288 my $modifiers = $INFO{$role}{modifiers}||[];
290 my @modifiers = grep !$composed_name->can($_),
291 do { my %h; @h{map @{$_}[1..$#$_-1], @$modifiers} = (); keys %h };
292 foreach my $modified (@modifiers) {
293 push @mod_base, "sub ${modified} { shift->next::method(\@_) }";
298 eval(my $code = join "\n", "package ${base_name};", @mod_base);
299 $e = "Evaling failed: $@\nTrying to eval:\n${code}" if $@;
302 $me->_install_modifiers($composed_name, $role);
303 $COMPOSED{role}{$composed_name} = {
304 modifiers_only => { map { $_ => 1 } @modifiers },
306 return $composed_name;
309 sub _check_requires {
310 my ($me, $to, $name, $requires) = @_;
311 return unless my @requires = @{$requires||$INFO{$name}{requires}||[]};
312 if (my @requires_fail = grep !$to->can($_), @requires) {
313 # role -> role, add to requires, role -> class, error out
314 if (my $to_info = $INFO{$to}) {
315 push @{$to_info->{requires}||=[]}, @requires_fail;
317 die "Can't apply ${name} to ${to} - missing ".join(', ', @requires_fail);
322 sub _concrete_methods_of {
323 my ($me, $role) = @_;
324 my $info = $INFO{$role};
325 # grab role symbol table
326 my $stash = _getstash($role);
327 # reverse so our keys become the values (captured coderefs) in case
328 # they got copied or re-used since
329 my $not_methods = { reverse %{$info->{not_methods}||{}} };
330 $info->{methods} ||= +{
331 # grab all code entries that aren't in the not_methods list
333 my $code = *{$stash->{$_}}{CODE};
334 ( ! $code or exists $not_methods->{$code} ) ? () : ($_ => $code)
335 } grep !ref($stash->{$_}), keys %$stash
339 sub methods_provided_by {
340 my ($me, $role) = @_;
341 die "${role} is not a Role::Tiny" unless $me->is_role($role);
342 (keys %{$me->_concrete_methods_of($role)}, @{$INFO{$role}->{requires}||[]});
345 sub _install_methods {
346 my ($me, $to, $role) = @_;
348 my $info = $INFO{$role};
350 my $methods = $me->_concrete_methods_of($role);
352 # grab target symbol table
353 my $stash = _getstash($to);
355 # determine already extant methods of target
358 +(ref($stash->{$_}) || *{$stash->{$_}}{CODE}),
362 foreach my $i (grep !exists $has_methods{$_}, keys %$methods) {
364 my $glob = _getglob "${to}::${i}";
365 *$glob = $methods->{$i};
367 # overloads using method names have the method stored in the scalar slot
368 # and &overload::nil in the code slot.
371 && defined &overload::nil
372 && $methods->{$i} == \&overload::nil;
374 my $overload = ${ *{_getglob "${role}::${i}"}{SCALAR} };
376 unless defined $overload;
381 $me->_install_does($to);
384 sub _install_modifiers {
385 my ($me, $to, $name) = @_;
386 return unless my $modifiers = $INFO{$name}{modifiers};
387 if (my $info = $INFO{$to}) {
388 push @{$info->{modifiers}}, @{$modifiers||[]};
390 foreach my $modifier (@{$modifiers||[]}) {
391 $me->_install_single_modifier($to, @$modifier);
398 sub _install_single_modifier {
399 my ($me, @args) = @_;
400 defined($vcheck_error) or $vcheck_error = do {
402 eval { Class::Method::Modifiers->VERSION(1.05); 1 }
406 $vcheck_error and die $vcheck_error;
407 Class::Method::Modifiers::install_modifier(@args);
410 my $FALLBACK = sub { 0 };
414 # only add does() method to classes
415 return if $me->is_role($to);
417 # add does() only if they don't have one
418 *{_getglob "${to}::does"} = \&does_role unless $to->can('does');
421 if $to->can('DOES') and $to->can('DOES') != (UNIVERSAL->can('DOES') || 0);
423 my $existing = $to->can('DOES') || $to->can('isa') || $FALLBACK;
425 my ($proto, $role) = @_;
426 Role::Tiny::does_role($proto, $role) or $proto->$existing($role);
428 no warnings 'redefine';
429 return *{_getglob "${to}::DOES"} = $new_sub;
433 my ($proto, $role) = @_;
434 require(_MRO_MODULE);
435 foreach my $class (@{mro::get_linear_isa(ref($proto)||$proto)}) {
436 return 1 if exists $APPLIED_TO{$class}{$role};
442 my ($me, $role) = @_;
443 return !!($INFO{$role} && $INFO{$role}{is_role});
453 Role::Tiny - Roles. Like a nouvelle cuisine portion size slice of Moose.
465 around baz => sub { ... }
473 use Role::Tiny::With;
475 # bar gets imported, but not foo
480 # baz is wrapped in the around modifier by Class::Method::Modifiers
485 If you wanted attributes as well, look at L<Moo::Role>.
489 C<Role::Tiny> is a minimalist role composition tool.
491 =head1 ROLE COMPOSITION
493 Role composition can be thought of as much more clever and meaningful multiple
494 inheritance. The basics of this implementation of roles is:
500 If a method is already defined on a class, that method will not be composed in
505 If a method that the role L</requires> to be implemented is not implemented,
506 role application will fail loudly.
510 Unlike L<Class::C3>, where the B<last> class inherited from "wins," role
511 composition is the other way around, where the class wins. If multiple roles
512 are applied in a single call (single with statement), then if any of their
513 provided methods clash, an exception is raised unless the class provides
514 a method since this conflict indicates a potential problem.
516 =head1 IMPORTED SUBROUTINES
520 requires qw(foo bar);
522 Declares a list of methods that must be defined to compose role.
528 with 'Some::Role1', 'Some::Role2';
530 Composes another role into the current role (or class via L<Role::Tiny::With>).
532 If you have conflicts and want to resolve them in favour of Some::Role1 you
538 If you have conflicts and want to resolve different conflicts in favour of
539 different roles, please refactor your codebase.
543 before foo => sub { ... };
545 See L<< Class::Method::Modifiers/before method(s) => sub { ... } >> for full
548 Note that since you are not required to use method modifiers,
549 L<Class::Method::Modifiers> is lazily loaded and we do not declare it as
550 a dependency. If your L<Role::Tiny> role uses modifiers you must depend on
551 both L<Class::Method::Modifiers> and L<Role::Tiny>.
555 around foo => sub { ... };
557 See L<< Class::Method::Modifiers/around method(s) => sub { ... } >> for full
560 Note that since you are not required to use method modifiers,
561 L<Class::Method::Modifiers> is lazily loaded and we do not declare it as
562 a dependency. If your L<Role::Tiny> role uses modifiers you must depend on
563 both L<Class::Method::Modifiers> and L<Role::Tiny>.
567 after foo => sub { ... };
569 See L<< Class::Method::Modifiers/after method(s) => sub { ... } >> for full
572 Note that since you are not required to use method modifiers,
573 L<Class::Method::Modifiers> is lazily loaded and we do not declare it as
574 a dependency. If your L<Role::Tiny> role uses modifiers you must depend on
575 both L<Class::Method::Modifiers> and L<Role::Tiny>.
577 =head2 Strict and Warnings
579 In addition to importing subroutines, using C<Role::Tiny> applies L<strict> and
580 L<fatal warnings|perllexwarn/Fatal Warnings> to the caller. It's possible to
581 disable these if desired:
584 use warnings NONFATAL => 'all';
590 if (Role::Tiny::does_role($foo, 'Some::Role')) {
594 Returns true if class has been composed with role.
596 This subroutine is also installed as ->does on any class a Role::Tiny is
597 composed into unless that class already has an ->does method, so
599 if ($foo->does('Some::Role')) {
603 will work for classes but to test a role, one must use ::does_role directly.
605 Additionally, Role::Tiny will override the standard Perl C<DOES> method
606 for your class. However, if C<any> class in your class' inheritance
607 hierarchy provides C<DOES>, then Role::Tiny will not override it.
611 =head2 apply_roles_to_package
613 Role::Tiny->apply_roles_to_package(
614 'Some::Package', 'Some::Role', 'Some::Other::Role'
617 Composes role with package. See also L<Role::Tiny::With>.
619 =head2 apply_roles_to_object
621 Role::Tiny->apply_roles_to_object($foo, qw(Some::Role1 Some::Role2));
623 Composes roles in order into object directly. Object is reblessed into the
626 =head2 create_class_with_roles
628 Role::Tiny->create_class_with_roles('Some::Base', qw(Some::Role1 Some::Role2));
630 Creates a new class based on base, with the roles composed into it in order.
631 New class is returned.
635 Role::Tiny->is_role('Some::Role1')
637 Returns true if the given package is a role.
643 =item * On perl 5.8.8 and earlier, applying a role to an object won't apply any
644 overloads from the role to all copies of the object.
650 L<Role::Tiny> is the attribute-less subset of L<Moo::Role>; L<Moo::Role> is
651 a meta-protocol-less subset of the king of role systems, L<Moose::Role>.
653 Ovid's L<Role::Basic> provides roles with a similar scope, but without method
654 modifiers, and having some extra usage restrictions.
658 mst - Matt S. Trout (cpan:MSTROUT) <mst@shadowcat.co.uk>
662 dg - David Leadbeater (cpan:DGL) <dgl@dgl.cx>
664 frew - Arthur Axel "fREW" Schmidt (cpan:FREW) <frioux@gmail.com>
666 hobbs - Andrew Rodland (cpan:ARODLAND) <arodland@cpan.org>
668 jnap - John Napiorkowski (cpan:JJNAPIORK) <jjn1056@yahoo.com>
670 ribasushi - Peter Rabbitson (cpan:RIBASUSHI) <ribasushi@cpan.org>
672 chip - Chip Salzenberg (cpan:CHIPS) <chip@pobox.com>
674 ajgb - Alex J. G. Burzyński (cpan:AJGB) <ajgb@cpan.org>
676 doy - Jesse Luehrs (cpan:DOY) <doy at tozt dot net>
678 perigrin - Chris Prather (cpan:PERIGRIN) <chris@prather.org>
680 Mithaldu - Christian Walde (cpan:MITHALDU) <walde.christian@googlemail.com>
682 ilmari - Dagfinn Ilmari Mannsåker (cpan:ILMARI) <ilmari@ilmari.org>
684 tobyink - Toby Inkster (cpan:TOBYINK) <tobyink@cpan.org>
686 haarg - Graham Knop (cpan:HAARG) <haarg@haarg.org>
690 Copyright (c) 2010-2012 the Role::Tiny L</AUTHOR> and L</CONTRIBUTORS>
695 This library is free software and may be distributed under the same terms