3 sub _getglob { \*{$_[0]} }
4 sub _getstash { \%{"$_[0]::"} }
7 use warnings FATAL => 'all';
9 our $VERSION = '1.000000'; # 1.0.0
10 $VERSION = eval $VERSION;
16 # Module state workaround totally stolen from Zefram's Module::Runtime.
19 *_WORK_AROUND_BROKEN_MODULE_STATE = "$]" < 5.009 ? sub(){1} : sub(){0};
22 sub Role::Tiny::__GUARD__::DESTROY {
23 delete $INC{$_[0]->[0]} if @{$_[0]};
27 (my $proto = $_[0]) =~ s/::/\//g;
29 return 1 if $INC{$proto};
30 # can't just ->can('can') because a sub-package Foo::Bar::Baz
31 # creates a 'Baz::' key in Foo::Bar's symbol table
32 return 1 if grep !/::$/, keys %{_getstash($_[0])||{}};
33 my $guard = _WORK_AROUND_BROKEN_MODULE_STATE
34 && bless([ $proto ], 'Role::Tiny::__GUARD__');
36 pop @$guard if _WORK_AROUND_BROKEN_MODULE_STATE;
44 return if $INFO{$target}; # already exported into this package
45 # get symbol table reference
46 my $stash = do { no strict 'refs'; \%{"${target}::"} };
47 # install before/after/around subs
48 foreach my $type (qw(before after around)) {
49 *{_getglob "${target}::${type}"} = sub {
50 require Class::Method::Modifiers;
51 push @{$INFO{$target}{modifiers}||=[]}, [ $type => @_ ];
54 *{_getglob "${target}::requires"} = sub {
55 push @{$INFO{$target}{requires}||=[]}, @_;
57 *{_getglob "${target}::with"} = sub {
58 die "Only one role supported at a time by with" if @_ > 1;
59 $me->apply_role_to_package($target, $_[0]);
61 # grab all *non-constant* (stash slot is not a scalarref) subs present
62 # in the symbol table and store their refaddrs (no need to forcibly
63 # inflate constant subs into real subs) - also add '' to here (this
65 @{$INFO{$target}{not_methods}={}}{
66 '', map { *$_{CODE}||() } grep !ref($_), values %$stash
69 $APPLIED_TO{$target} = { $target => undef };
72 sub apply_role_to_package {
73 my ($me, $to, $role) = @_;
77 die "This is apply_role_to_package" if ref($to);
78 die "${role} is not a Role::Tiny" unless my $info = $INFO{$role};
80 $me->_check_requires($to, $role, @{$info->{requires}||[]});
82 $me->_install_methods($to, $role);
84 $me->_install_modifiers($to, $info->{modifiers});
86 # only add does() method to classes and only if they don't have one
87 if (not $INFO{$to} and not $to->can('does')) {
88 *{_getglob "${to}::does"} = \&does_role;
91 # copy our role list into the target's
92 @{$APPLIED_TO{$to}||={}}{keys %{$APPLIED_TO{$role}}} = ();
95 sub apply_roles_to_object {
96 my ($me, $object, @roles) = @_;
97 die "No roles supplied!" unless @roles;
98 my $class = ref($object);
99 bless($object, $me->create_class_with_roles($class, @roles));
103 sub create_class_with_roles {
104 my ($me, $superclass, @roles) = @_;
106 die "No roles supplied!" unless @roles;
109 '__WITH__', $superclass, my $compose_name = join '__AND__', @roles
112 return $new_name if $COMPOSED{class}{$new_name};
114 foreach my $role (@roles) {
116 die "${role} is not a Role::Tiny" unless my $info = $INFO{$role};
125 my @composable = map $me->_composable_package_for($_), reverse @roles;
127 *{_getglob("${new_name}::ISA")} = [ @composable, $superclass ];
129 my @info = map +($INFO{$_} ? $INFO{$_} : ()), @roles;
131 $me->_check_requires(
132 $new_name, $compose_name,
133 do { my %h; @h{map @{$_->{requires}||[]}, @info} = (); keys %h }
136 *{_getglob "${new_name}::does"} = \&does_role unless $new_name->can('does');
138 @{$APPLIED_TO{$new_name}||={}}{
139 map keys %{$APPLIED_TO{$_}}, @roles
142 $COMPOSED{class}{$new_name} = 1;
146 sub _composable_package_for {
147 my ($me, $role) = @_;
148 my $composed_name = 'Role::Tiny::_COMPOSABLE::'.$role;
149 return $composed_name if $COMPOSED{role}{$composed_name};
150 $me->_install_methods($composed_name, $role);
151 my $base_name = $composed_name.'::_BASE';
152 *{_getglob("${composed_name}::ISA")} = [ $base_name ];
153 my $modifiers = $INFO{$role}{modifiers}||[];
155 foreach my $modified (
156 do { my %h; @h{map $_->[1], @$modifiers} = (); keys %h }
158 push @mod_base, "sub ${modified} { shift->next::method(\@_) }";
162 eval(my $code = join "\n", "package ${base_name};", @mod_base);
163 die "Evaling failed: $@\nTrying to eval:\n${code}" if $@;
165 $me->_install_modifiers($composed_name, $modifiers);
166 $COMPOSED{role}{$composed_name} = 1;
167 return $composed_name;
170 sub _check_requires {
171 my ($me, $to, $name, @requires) = @_;
172 if (my @requires_fail = grep !$to->can($_), @requires) {
173 # role -> role, add to requires, role -> class, error out
174 if (my $to_info = $INFO{$to}) {
175 push @{$to_info->{requires}||=[]}, @requires_fail;
177 die "Can't apply ${name} to ${to} - missing ".join(', ', @requires_fail);
182 sub _concrete_methods_of {
183 my ($me, $role) = @_;
184 my $info = $INFO{$role};
185 $info->{methods} ||= do {
186 # grab role symbol table
187 my $stash = do { no strict 'refs'; \%{"${role}::"}};
188 my $not_methods = $info->{not_methods};
190 # grab all code entries that aren't in the not_methods list
192 my $code = *{$stash->{$_}}{CODE};
193 # rely on the '' key we added in import for "no code here"
194 exists $not_methods->{$code||''} ? () : ($_ => $code)
195 } grep !ref($stash->{$_}), keys %$stash
200 sub methods_provided_by {
201 my ($me, $role) = @_;
202 die "${role} is not a Role::Tiny" unless my $info = $INFO{$role};
203 (keys %{$me->_concrete_methods_of($role)}, @{$info->{requires}||[]});
206 sub _install_methods {
207 my ($me, $to, $role) = @_;
209 my $info = $INFO{$role};
211 my $methods = $me->_concrete_methods_of($role);
213 # grab target symbol table
214 my $stash = do { no strict 'refs'; \%{"${to}::"}};
216 # determine already extant methods of target
219 +(ref($stash->{$_}) || *{$stash->{$_}}{CODE}),
223 foreach my $i (grep !exists $has_methods{$_}, keys %$methods) {
225 *{_getglob "${to}::${i}"} = $methods->{$i};
229 sub _install_modifiers {
230 my ($me, $to, $modifiers) = @_;
231 if (my $info = $INFO{$to}) {
232 push @{$info->{modifiers}}, @{$modifiers||[]};
234 foreach my $modifier (@{$modifiers||[]}) {
235 $me->_install_single_modifier($to, @$modifier);
240 sub _install_single_modifier {
241 my ($me, @args) = @_;
242 Class::Method::Modifiers::install_modifier(@args);
246 my ($proto, $role) = @_;
247 return exists $APPLIED_TO{ref($proto)||$proto}{$role};
254 Role::Tiny - Roles. Like a nouvelle cusine portion size slice of Moose.
272 use Role::Tiny::With;
274 # bar gets imported, but not foo
283 C<Role::Tiny> is a minimalist role composition tool.
285 =head1 ROLE COMPOSITION
287 Role composition can be thought of as much more clever and meaningful multiple
288 inheritance. The basics of this implementation of roles is:
294 If a method is already defined on a class, that method will not be composed in
299 If a method that the role L</requires> to be implemented is not implemented,
300 role application will fail loudly.
304 Unlike L<Class::C3>, where the B<last> class inherited from "wins," role
305 composition is the other way around, where first wins. In a more complete
306 system (see L<Moose>) roles are checked to see if they clash. The goal of this
307 is to be much simpler, hence disallowing composition of multiple roles at once.
311 =head2 apply_role_to_package
313 Role::Tiny->apply_role_to_package('Some::Package', 'Some::Role');
315 Composes role with package. See also L<Role::Tiny::With>.
317 =head2 apply_roles_to_object
319 Role::Tiny->apply_roles_to_object($foo, qw(Some::Role1 Some::Role2));
321 Composes roles in order into object directly. Object is reblessed into the
324 =head2 create_class_with_roles
326 Role::Tiny->create_class_with_roles('Some::Base', qw(Some::Role1 Some::Role2));
328 Creates a new class based on base, with the roles composed into it in order.
329 New class is returned.
335 if (Role::Tiny::does_role($foo, 'Some::Role')) {
339 Returns true if class has been composed with role.
341 This subroutine is also installed as ->does on any class a Role::Tiny is
342 composed into unless that class already has an ->does method, so
344 if ($foo->does_role('Some::Role')) {
348 will work for classes but to test a role, one must use ::does_role directly
350 =head1 IMPORTED SUBROUTINES
354 requires qw(foo bar);
356 Declares a list of methods that must be defined to compose role.
363 Composes another role into the current role. Only one role may be composed in
364 at a time to allow the code to remain as simple as possible.
368 before foo => sub { ... };
370 See L<< Class::Method::Modifiers/before method(s) => sub { ... } >> for full
375 around foo => sub { ... };
377 See L<< Class::Method::Modifiers/around method(s) => sub { ... } >> for full
382 after foo => sub { ... };
384 See L<< Class::Method::Modifiers/after method(s) => sub { ... } >> for full
389 mst - Matt S. Trout (cpan:MSTROUT) <mst@shadowcat.co.uk>
393 dg - David Leadbeater (cpan:DGL) <dgl@dgl.cx>
395 frew - Arthur Axel "fREW" Schmidt (cpan:FREW) <frioux@gmail.com>
397 hobbs - Andrew Rodland (cpan:ARODLAND) <arodland@cpan.org>
399 jnap - John Napiorkowski (cpan:JJNAPIORK) <jjn1056@yahoo.com>
401 ribasushi - Peter Rabbitson (cpan:RIBASUSHI) <ribasushi@cpan.org>
403 chip - Chip Salzenberg (cpan:CHIPS) <chip@pobox.com>
405 ajgb - Alex J. G. BurzyĆski (cpan:AJGB) <ajgb@cpan.org>
407 doy - Jesse Luehrs (cpan:DOY) <doy at tozt dot net>
409 perigrin - Chris Prather (cpan:PERIGRIN) <chris@prather.org>
413 Copyright (c) 2010-2012 the Role::Tiny L</AUTHOR> and L</CONTRIBUTORS>
418 This library is free software and may be distributed under the same terms