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 $me->apply_union_of_roles_to_package($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} = { $target => undef };
73 sub apply_role_to_package {
74 my ($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_union_of_roles_to_package {
156 my ($me, $to, @roles) = @_;
158 return $me->apply_role_to_package($to, $roles[0]) if @roles == 1;
160 my %conflicts = %{$me->_union_info_for(@roles)->{conflicts}};
161 delete $conflicts{$_} for $me->_concrete_methods_of($to);
162 if (keys %conflicts) {
166 "Due to a method name conflict between roles "
167 ."'".join(' and ', sort values %{$conflicts{$_}})."'"
168 .", the method '$_' must be implemented by '${to}'"
172 $me->apply_role_to_package($to, $_) for @roles;
173 $APPLIED_TO{$to}{join('|',@roles)} = 1;
176 sub _union_info_for {
177 my ($me, @roles) = @_;
178 $UNION_INFO{join('|', sort @roles)} ||= do {
179 _load_module($_) for @roles;
181 foreach my $role (@roles) {
182 my $this_methods = $me->_concrete_methods_of($role);
183 $methods{$_}{$this_methods->{$_}} = $role for keys %$this_methods;
185 delete $methods{$_} for grep keys(%{$methods{$_}}) == 1, keys %methods;
186 +{ conflicts => \%methods }
190 sub _composable_package_for {
191 my ($me, $role) = @_;
192 my $composed_name = 'Role::Tiny::_COMPOSABLE::'.$role;
193 return $composed_name if $COMPOSED{role}{$composed_name};
194 $me->_install_methods($composed_name, $role);
195 my $base_name = $composed_name.'::_BASE';
196 *{_getglob("${composed_name}::ISA")} = [ $base_name ];
197 my $modifiers = $INFO{$role}{modifiers}||[];
199 foreach my $modified (
200 do { my %h; @h{map $_->[1], @$modifiers} = (); keys %h }
202 push @mod_base, "sub ${modified} { shift->next::method(\@_) }";
207 eval(my $code = join "\n", "package ${base_name};", @mod_base);
208 $e = "Evaling failed: $@\nTrying to eval:\n${code}" if $@;
211 $me->_install_modifiers($composed_name, $modifiers);
212 $COMPOSED{role}{$composed_name} = 1;
213 return $composed_name;
216 sub _check_requires {
217 my ($me, $to, $name, @requires) = @_;
218 if (my @requires_fail = grep !$to->can($_), @requires) {
219 # role -> role, add to requires, role -> class, error out
220 if (my $to_info = $INFO{$to}) {
221 push @{$to_info->{requires}||=[]}, @requires_fail;
223 die "Can't apply ${name} to ${to} - missing ".join(', ', @requires_fail);
228 sub _concrete_methods_of {
229 my ($me, $role) = @_;
230 my $info = $INFO{$role};
231 # grab role symbol table
232 my $stash = do { no strict 'refs'; \%{"${role}::"}};
233 my $not_methods = $info->{not_methods};
235 # grab all code entries that aren't in the not_methods list
237 my $code = *{$stash->{$_}}{CODE};
238 # rely on the '' key we added in import for "no code here"
239 exists $not_methods->{$code||''} ? () : ($_ => $code)
240 } grep !ref($stash->{$_}), keys %$stash
244 sub methods_provided_by {
245 my ($me, $role) = @_;
246 die "${role} is not a Role::Tiny" unless my $info = $INFO{$role};
247 (keys %{$me->_concrete_methods_of($role)}, @{$info->{requires}||[]});
250 sub _install_methods {
251 my ($me, $to, $role) = @_;
253 my $info = $INFO{$role};
255 my $methods = $me->_concrete_methods_of($role);
257 # grab target symbol table
258 my $stash = do { no strict 'refs'; \%{"${to}::"}};
260 # determine already extant methods of target
263 +(ref($stash->{$_}) || *{$stash->{$_}}{CODE}),
267 foreach my $i (grep !exists $has_methods{$_}, keys %$methods) {
269 *{_getglob "${to}::${i}"} = $methods->{$i};
273 sub _install_modifiers {
274 my ($me, $to, $modifiers) = @_;
275 if (my $info = $INFO{$to}) {
276 push @{$info->{modifiers}}, @{$modifiers||[]};
278 foreach my $modifier (@{$modifiers||[]}) {
279 $me->_install_single_modifier($to, @$modifier);
284 sub _install_single_modifier {
285 my ($me, @args) = @_;
286 Class::Method::Modifiers::install_modifier(@args);
290 my ($proto, $role) = @_;
291 return exists $APPLIED_TO{ref($proto)||$proto}{$role};
298 Role::Tiny - Roles. Like a nouvelle cuisine portion size slice of Moose.
310 around baz => sub { ... }
318 use Role::Tiny::With;
320 # bar gets imported, but not foo
325 # baz is wrapped in the around modifier by Class::Method::Modifiers
330 If you wanted attributes as well, look at L<Moo::Role>.
334 C<Role::Tiny> is a minimalist role composition tool.
336 =head1 ROLE COMPOSITION
338 Role composition can be thought of as much more clever and meaningful multiple
339 inheritance. The basics of this implementation of roles is:
345 If a method is already defined on a class, that method will not be composed in
350 If a method that the role L</requires> to be implemented is not implemented,
351 role application will fail loudly.
355 Unlike L<Class::C3>, where the B<last> class inherited from "wins," role
356 composition is the other way around, where first wins. In a more complete
357 system (see L<Moose>) roles are checked to see if they clash. The goal of this
358 is to be much simpler, hence disallowing composition of multiple roles at once.
362 =head2 apply_role_to_package
364 Role::Tiny->apply_role_to_package('Some::Package', 'Some::Role');
366 Composes role with package. See also L<Role::Tiny::With>.
368 =head2 apply_roles_to_object
370 Role::Tiny->apply_roles_to_object($foo, qw(Some::Role1 Some::Role2));
372 Composes roles in order into object directly. Object is reblessed into the
375 =head2 create_class_with_roles
377 Role::Tiny->create_class_with_roles('Some::Base', qw(Some::Role1 Some::Role2));
379 Creates a new class based on base, with the roles composed into it in order.
380 New class is returned.
386 if (Role::Tiny::does_role($foo, 'Some::Role')) {
390 Returns true if class has been composed with role.
392 This subroutine is also installed as ->does on any class a Role::Tiny is
393 composed into unless that class already has an ->does method, so
395 if ($foo->does('Some::Role')) {
399 will work for classes but to test a role, one must use ::does_role directly
401 =head1 IMPORTED SUBROUTINES
405 requires qw(foo bar);
407 Declares a list of methods that must be defined to compose role.
414 Composes another role into the current role. Only one role may be composed in
415 at a time to allow the code to remain as simple as possible.
419 before foo => sub { ... };
421 See L<< Class::Method::Modifiers/before method(s) => sub { ... } >> for full
424 Note that since you are not required to use method modifiers,
425 L<Class::Method::Modifiers> is lazily loaded and we do not declare it as
426 a dependency. If your L<Role::Tiny> role uses modifiers you must depend on
427 both L<Class::Method::Modifiers> and L<Role::Tiny>.
431 around foo => sub { ... };
433 See L<< Class::Method::Modifiers/around method(s) => sub { ... } >> for full
436 Note that since you are not required to use method modifiers,
437 L<Class::Method::Modifiers> is lazily loaded and we do not declare it as
438 a dependency. If your L<Role::Tiny> role uses modifiers you must depend on
439 both L<Class::Method::Modifiers> and L<Role::Tiny>.
443 after foo => sub { ... };
445 See L<< Class::Method::Modifiers/after method(s) => sub { ... } >> for full
448 Note that since you are not required to use method modifiers,
449 L<Class::Method::Modifiers> is lazily loaded and we do not declare it as
450 a dependency. If your L<Role::Tiny> role uses modifiers you must depend on
451 both L<Class::Method::Modifiers> and L<Role::Tiny>.
455 L<Role::Tiny> is the attribute-less subset of L<Moo::Role>; L<Moo::Role> is
456 a meta-protocol-less subset of the king of role systems, L<Moose::Role>.
458 If you don't want method modifiers and do want to be forcibly restricted
459 to a single role application per class, Ovid's L<Role::Basic> exists. But
460 Stevan Little (the L<Moose> author) and I are both still convinced that
465 mst - Matt S. Trout (cpan:MSTROUT) <mst@shadowcat.co.uk>
469 dg - David Leadbeater (cpan:DGL) <dgl@dgl.cx>
471 frew - Arthur Axel "fREW" Schmidt (cpan:FREW) <frioux@gmail.com>
473 hobbs - Andrew Rodland (cpan:ARODLAND) <arodland@cpan.org>
475 jnap - John Napiorkowski (cpan:JJNAPIORK) <jjn1056@yahoo.com>
477 ribasushi - Peter Rabbitson (cpan:RIBASUSHI) <ribasushi@cpan.org>
479 chip - Chip Salzenberg (cpan:CHIPS) <chip@pobox.com>
481 ajgb - Alex J. G. BurzyĆski (cpan:AJGB) <ajgb@cpan.org>
483 doy - Jesse Luehrs (cpan:DOY) <doy at tozt dot net>
485 perigrin - Chris Prather (cpan:PERIGRIN) <chris@prather.org>
489 Copyright (c) 2010-2012 the Role::Tiny L</AUTHOR> and L</CONTRIBUTORS>
494 This library is free software and may be distributed under the same terms