3 sub _getglob { \*{$_[0]} }
4 sub _getstash { \%{"$_[0]::"} }
7 use warnings FATAL => 'all';
9 our $VERSION = '1.002004'; # 1.2.4
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 $stash = _getstash($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}||=[]}, [ $type => @_ ];
57 *{_getglob "${target}::requires"} = sub {
58 push @{$INFO{$target}{requires}||=[]}, @_;
61 *{_getglob "${target}::with"} = sub {
62 $me->apply_roles_to_package($target, @_);
65 # grab all *non-constant* (stash slot is not a scalarref) subs present
66 # in the symbol table and store their refaddrs (no need to forcibly
67 # inflate constant subs into real subs) - also add '' to here (this
68 # is used later) with a map to the coderefs in case of copying or re-use
69 my @not_methods = ('', map { *$_{CODE}||() } grep !ref($_), values %$stash);
70 @{$INFO{$target}{not_methods}={}}{@not_methods} = @not_methods;
72 $APPLIED_TO{$target} = { $target => undef };
75 sub apply_single_role_to_package {
76 my ($me, $to, $role) = @_;
80 die "This is apply_role_to_package" if ref($to);
81 die "${role} is not a Role::Tiny" unless my $info = $INFO{$role};
83 $me->_check_requires($to, $role, @{$info->{requires}||[]});
85 $me->_install_methods($to, $role);
87 $me->_install_modifiers($to, $info->{modifiers});
89 # copy our role list into the target's
90 @{$APPLIED_TO{$to}||={}}{keys %{$APPLIED_TO{$role}}} = ();
93 sub apply_roles_to_object {
94 my ($me, $object, @roles) = @_;
95 die "No roles supplied!" unless @roles;
96 my $class = ref($object);
97 bless($object, $me->create_class_with_roles($class, @roles));
101 sub create_class_with_roles {
102 my ($me, $superclass, @roles) = @_;
104 die "No roles supplied!" unless @roles;
106 _load_module($superclass);
109 $seen{$_}++ for @roles;
110 if (my @dupes = grep $seen{$_} > 1, @roles) {
111 die "Duplicated roles: ".join(', ', @dupes);
116 '__WITH__', $superclass, my $compose_name = join '__AND__', @roles
119 return $new_name if $COMPOSED{class}{$new_name};
121 foreach my $role (@roles) {
123 die "${role} is not a Role::Tiny" unless $INFO{$role};
132 my %conflicts = %{$me->_composite_info_for(@roles)->{conflicts}};
133 if (keys %conflicts) {
137 "Method name conflict for '$_' between roles "
138 ."'".join(' and ', sort values %{$conflicts{$_}})."'"
139 .", cannot apply these simultaneously to an object."
144 my @composable = map $me->_composable_package_for($_), reverse @roles;
146 *{_getglob("${new_name}::ISA")} = [ @composable, $superclass ];
148 my @info = map $INFO{$_}, @roles;
150 $me->_check_requires(
151 $new_name, $compose_name,
152 do { my %h; @h{map @{$_->{requires}||[]}, @info} = (); keys %h }
155 @{$APPLIED_TO{$new_name}||={}}{
156 map keys %{$APPLIED_TO{$_}}, @roles
159 $COMPOSED{class}{$new_name} = 1;
163 # preserved for compat, and apply_roles_to_package calls it to allow an
164 # updated Role::Tiny to use a non-updated Moo::Role
166 sub apply_role_to_package { shift->apply_single_role_to_package(@_) }
168 sub apply_roles_to_package {
169 my ($me, $to, @roles) = @_;
171 return $me->apply_role_to_package($to, $roles[0]) if @roles == 1;
173 my %conflicts = %{$me->_composite_info_for(@roles)->{conflicts}};
174 delete $conflicts{$_} for $me->_concrete_methods_of($to);
175 if (keys %conflicts) {
179 "Due to a method name conflict between roles "
180 ."'".join(' and ', sort values %{$conflicts{$_}})."'"
181 .", the method '$_' must be implemented by '${to}'"
186 # the if guard here is essential since otherwise we accidentally create
187 # a $INFO for something that isn't a Role::Tiny (or Moo::Role) because
188 # autovivification hates us and wants us to die()
190 delete $INFO{$to}{methods}; # reset since we're about to add methods
193 $me->apply_role_to_package($to, $_) for @roles;
194 $APPLIED_TO{$to}{join('|',@roles)} = 1;
197 sub _composite_info_for {
198 my ($me, @roles) = @_;
199 $COMPOSITE_INFO{join('|', sort @roles)} ||= do {
200 _load_module($_) for @roles;
202 foreach my $role (@roles) {
203 my $this_methods = $me->_concrete_methods_of($role);
204 $methods{$_}{$this_methods->{$_}} = $role for keys %$this_methods;
206 delete $methods{$_} for grep keys(%{$methods{$_}}) == 1, keys %methods;
207 +{ conflicts => \%methods }
211 sub _composable_package_for {
212 my ($me, $role) = @_;
213 my $composed_name = 'Role::Tiny::_COMPOSABLE::'.$role;
214 return $composed_name if $COMPOSED{role}{$composed_name};
215 $me->_install_methods($composed_name, $role);
216 my $base_name = $composed_name.'::_BASE';
217 # Not using _getglob, since setting @ISA via the typeglob breaks
218 # inheritance on 5.10.0 if the stash has previously been accessed an
219 # then a method called on the class (in that order!), which
220 # ->_install_methods (with the help of ->_install_does) ends up doing.
221 { no strict 'refs'; @{"${composed_name}::ISA"} = ( $base_name ); }
222 my $modifiers = $INFO{$role}{modifiers}||[];
224 foreach my $modified (
225 do { my %h; @h{map $_->[1], @$modifiers} = (); keys %h }
227 push @mod_base, "sub ${modified} { shift->next::method(\@_) }";
232 eval(my $code = join "\n", "package ${base_name};", @mod_base);
233 $e = "Evaling failed: $@\nTrying to eval:\n${code}" if $@;
236 $me->_install_modifiers($composed_name, $modifiers);
237 $COMPOSED{role}{$composed_name} = 1;
238 return $composed_name;
241 sub _check_requires {
242 my ($me, $to, $name, @requires) = @_;
243 if (my @requires_fail = grep !$to->can($_), @requires) {
244 # role -> role, add to requires, role -> class, error out
245 if (my $to_info = $INFO{$to}) {
246 push @{$to_info->{requires}||=[]}, @requires_fail;
248 die "Can't apply ${name} to ${to} - missing ".join(', ', @requires_fail);
253 sub _concrete_methods_of {
254 my ($me, $role) = @_;
255 my $info = $INFO{$role};
256 # grab role symbol table
257 my $stash = _getstash($role);
258 # reverse so our keys become the values (captured coderefs) in case
259 # they got copied or re-used since
260 my $not_methods = { reverse %{$info->{not_methods}||{}} };
261 $info->{methods} ||= +{
262 # grab all code entries that aren't in the not_methods list
264 my $code = *{$stash->{$_}}{CODE};
265 # rely on the '' key we added in import for "no code here"
266 exists $not_methods->{$code||''} ? () : ($_ => $code)
267 } grep !ref($stash->{$_}), keys %$stash
271 sub methods_provided_by {
272 my ($me, $role) = @_;
273 die "${role} is not a Role::Tiny" unless my $info = $INFO{$role};
274 (keys %{$me->_concrete_methods_of($role)}, @{$info->{requires}||[]});
277 sub _install_methods {
278 my ($me, $to, $role) = @_;
280 my $info = $INFO{$role};
282 my $methods = $me->_concrete_methods_of($role);
284 # grab target symbol table
285 my $stash = _getstash($to);
287 # determine already extant methods of target
290 +(ref($stash->{$_}) || *{$stash->{$_}}{CODE}),
294 foreach my $i (grep !exists $has_methods{$_}, keys %$methods) {
296 *{_getglob "${to}::${i}"} = $methods->{$i};
299 $me->_install_does($to);
302 sub _install_modifiers {
303 my ($me, $to, $modifiers) = @_;
304 if (my $info = $INFO{$to}) {
305 push @{$info->{modifiers}}, @{$modifiers||[]};
307 foreach my $modifier (@{$modifiers||[]}) {
308 $me->_install_single_modifier($to, @$modifier);
313 sub _install_single_modifier {
314 my ($me, @args) = @_;
315 Class::Method::Modifiers::install_modifier(@args);
318 my $FALLBACK = sub { 0 };
322 # only add does() method to classes
323 return if $INFO{$to};
325 # add does() only if they don't have one
326 *{_getglob "${to}::does"} = \&does_role unless $to->can('does');
328 return if ($to->can('DOES') and $to->can('DOES') != (UNIVERSAL->can('DOES') || 0));
330 my $existing = $to->can('DOES') || $to->can('isa') || $FALLBACK;
332 my ($proto, $role) = @_;
333 Role::Tiny::does_role($proto, $role) or $proto->$existing($role);
335 no warnings 'redefine';
336 *{_getglob "${to}::DOES"} = $new_sub;
340 my ($proto, $role) = @_;
346 foreach my $class (@{mro::get_linear_isa(ref($proto)||$proto)}) {
347 return 1 if exists $APPLIED_TO{$class}{$role};
356 Role::Tiny - Roles. Like a nouvelle cuisine portion size slice of Moose.
368 around baz => sub { ... }
376 use Role::Tiny::With;
378 # bar gets imported, but not foo
383 # baz is wrapped in the around modifier by Class::Method::Modifiers
388 If you wanted attributes as well, look at L<Moo::Role>.
392 C<Role::Tiny> is a minimalist role composition tool.
394 =head1 ROLE COMPOSITION
396 Role composition can be thought of as much more clever and meaningful multiple
397 inheritance. The basics of this implementation of roles is:
403 If a method is already defined on a class, that method will not be composed in
408 If a method that the role L</requires> to be implemented is not implemented,
409 role application will fail loudly.
413 Unlike L<Class::C3>, where the B<last> class inherited from "wins," role
414 composition is the other way around, where the class wins. If multiple roles
415 are applied in a single call (single with statement), then if any of their
416 provided methods clash, an exception is raised unless the class provides
417 a method since this conflict indicates a potential problem.
419 =head1 IMPORTED SUBROUTINES
423 requires qw(foo bar);
425 Declares a list of methods that must be defined to compose role.
431 with 'Some::Role1', 'Some::Role2';
433 Composes another role into the current role (or class via L<Role::Tiny::With>).
435 If you have conflicts and want to resolve them in favour of Some::Role1 you
441 If you have conflicts and want to resolve different conflicts in favour of
442 different roles, please refactor your codebase.
446 before foo => sub { ... };
448 See L<< Class::Method::Modifiers/before 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 around foo => sub { ... };
460 See L<< Class::Method::Modifiers/around 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 after foo => sub { ... };
472 See L<< Class::Method::Modifiers/after method(s) => sub { ... } >> for full
475 Note that since you are not required to use method modifiers,
476 L<Class::Method::Modifiers> is lazily loaded and we do not declare it as
477 a dependency. If your L<Role::Tiny> role uses modifiers you must depend on
478 both L<Class::Method::Modifiers> and L<Role::Tiny>.
484 if (Role::Tiny::does_role($foo, 'Some::Role')) {
488 Returns true if class has been composed with role.
490 This subroutine is also installed as ->does on any class a Role::Tiny is
491 composed into unless that class already has an ->does method, so
493 if ($foo->does('Some::Role')) {
497 will work for classes but to test a role, one must use ::does_role directly.
499 Additionally, Role::Tiny will override the standard Perl C<DOES> method
500 for your class. However, if C<any> class in your class' inheritance
501 heirarchy provides C<DOES>, then Role::Tiny will not override it.
505 =head2 apply_roles_to_package
507 Role::Tiny->apply_roles_to_package(
508 'Some::Package', 'Some::Role', 'Some::Other::Role'
511 Composes role with package. See also L<Role::Tiny::With>.
513 =head2 apply_roles_to_object
515 Role::Tiny->apply_roles_to_object($foo, qw(Some::Role1 Some::Role2));
517 Composes roles in order into object directly. Object is reblessed into the
520 =head2 create_class_with_roles
522 Role::Tiny->create_class_with_roles('Some::Base', qw(Some::Role1 Some::Role2));
524 Creates a new class based on base, with the roles composed into it in order.
525 New class is returned.
529 L<Role::Tiny> is the attribute-less subset of L<Moo::Role>; L<Moo::Role> is
530 a meta-protocol-less subset of the king of role systems, L<Moose::Role>.
532 If you don't want method modifiers and do want to be forcibly restricted
533 to a single role application per class, Ovid's L<Role::Basic> exists. But
534 Stevan Little (the L<Moose> author) and I don't find the additional
535 restrictions to be amazingly helpful in most cases; L<Role::Basic>'s choices
536 are more a guide to what you should prefer doing, to our mind, rather than
537 something that needs to be enforced.
541 mst - Matt S. Trout (cpan:MSTROUT) <mst@shadowcat.co.uk>
545 dg - David Leadbeater (cpan:DGL) <dgl@dgl.cx>
547 frew - Arthur Axel "fREW" Schmidt (cpan:FREW) <frioux@gmail.com>
549 hobbs - Andrew Rodland (cpan:ARODLAND) <arodland@cpan.org>
551 jnap - John Napiorkowski (cpan:JJNAPIORK) <jjn1056@yahoo.com>
553 ribasushi - Peter Rabbitson (cpan:RIBASUSHI) <ribasushi@cpan.org>
555 chip - Chip Salzenberg (cpan:CHIPS) <chip@pobox.com>
557 ajgb - Alex J. G. Burzyński (cpan:AJGB) <ajgb@cpan.org>
559 doy - Jesse Luehrs (cpan:DOY) <doy at tozt dot net>
561 perigrin - Chris Prather (cpan:PERIGRIN) <chris@prather.org>
563 Mithaldu - Christian Walde (cpan:MITHALDU) <walde.christian@googlemail.com>
565 ilmari - Dagfinn Ilmari Mannsåker (cpan:ILMARI) <ilmari@ilmari.org>
567 tobyink - Toby Inkster (cpan:TOBYINK) <tobyink@cpan.org>
571 Copyright (c) 2010-2012 the Role::Tiny L</AUTHOR> and L</CONTRIBUTORS>
576 This library is free software and may be distributed under the same terms