Commit | Line | Data |
ab3370e7 |
1 | package Role::Tiny; |
2 | |
119014a7 |
3 | sub _getglob { \*{$_[0]} } |
5e03b55c |
4 | sub _getstash { \%{"$_[0]::"} } |
119014a7 |
5 | |
b1eebd55 |
6 | use strict; |
7 | use warnings FATAL => 'all'; |
ab3370e7 |
8 | |
e2722751 |
9 | our $VERSION = '1.000001'; # 1.0.1 |
c334a5c1 |
10 | $VERSION = eval $VERSION; |
11 | |
ab3370e7 |
12 | our %INFO; |
13 | our %APPLIED_TO; |
1947330a |
14 | our %COMPOSED; |
671b5a88 |
15 | our %UNION_INFO; |
ab3370e7 |
16 | |
cf62c989 |
17 | # Module state workaround totally stolen from Zefram's Module::Runtime. |
18 | |
19 | BEGIN { |
20 | *_WORK_AROUND_BROKEN_MODULE_STATE = "$]" < 5.009 ? sub(){1} : sub(){0}; |
21 | } |
22 | |
23 | sub Role::Tiny::__GUARD__::DESTROY { |
24 | delete $INC{$_[0]->[0]} if @{$_[0]}; |
25 | } |
5e03b55c |
26 | |
fb5074f6 |
27 | sub _load_module { |
fb5074f6 |
28 | (my $proto = $_[0]) =~ s/::/\//g; |
cf62c989 |
29 | $proto .= '.pm'; |
30 | return 1 if $INC{$proto}; |
5e03b55c |
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])||{}}; |
cf62c989 |
34 | my $guard = _WORK_AROUND_BROKEN_MODULE_STATE |
35 | && bless([ $proto ], 'Role::Tiny::__GUARD__'); |
36 | require $proto; |
37 | pop @$guard if _WORK_AROUND_BROKEN_MODULE_STATE; |
fb5074f6 |
38 | return 1; |
39 | } |
40 | |
ab3370e7 |
41 | sub import { |
42 | my $target = caller; |
a1164a0b |
43 | my $me = shift; |
3ca7ff56 |
44 | strict->import; |
45 | warnings->import(FATAL => 'all'); |
1ba11455 |
46 | return if $INFO{$target}; # already exported into this package |
ab3370e7 |
47 | # get symbol table reference |
48 | my $stash = do { no strict 'refs'; \%{"${target}::"} }; |
49 | # install before/after/around subs |
50 | foreach my $type (qw(before after around)) { |
5a247406 |
51 | *{_getglob "${target}::${type}"} = sub { |
7568ba55 |
52 | require Class::Method::Modifiers; |
ab3370e7 |
53 | push @{$INFO{$target}{modifiers}||=[]}, [ $type => @_ ]; |
54 | }; |
55 | } |
5a247406 |
56 | *{_getglob "${target}::requires"} = sub { |
ab3370e7 |
57 | push @{$INFO{$target}{requires}||=[]}, @_; |
58 | }; |
5a247406 |
59 | *{_getglob "${target}::with"} = sub { |
60dfe768 |
60 | $me->apply_union_of_roles_to_package($target, @_); |
96d3f07a |
61 | }; |
7b8177f8 |
62 | # grab all *non-constant* (stash slot is not a scalarref) subs present |
ab3370e7 |
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 |
65 | # is used later) |
66 | @{$INFO{$target}{not_methods}={}}{ |
faa9ce11 |
67 | '', map { *$_{CODE}||() } grep !ref($_), values %$stash |
ab3370e7 |
68 | } = (); |
69 | # a role does itself |
70 | $APPLIED_TO{$target} = { $target => undef }; |
71 | } |
72 | |
73 | sub apply_role_to_package { |
369a4c50 |
74 | my ($me, $to, $role) = @_; |
1947330a |
75 | |
fb5074f6 |
76 | _load_module($role); |
77 | |
ab3370e7 |
78 | die "This is apply_role_to_package" if ref($to); |
1947330a |
79 | die "${role} is not a Role::Tiny" unless my $info = $INFO{$role}; |
80 | |
81 | $me->_check_requires($to, $role, @{$info->{requires}||[]}); |
82 | |
83 | $me->_install_methods($to, $role); |
84 | |
85 | $me->_install_modifiers($to, $info->{modifiers}); |
86 | |
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; |
90 | } |
91 | |
1947330a |
92 | # copy our role list into the target's |
93 | @{$APPLIED_TO{$to}||={}}{keys %{$APPLIED_TO{$role}}} = (); |
94 | } |
95 | |
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)); |
101 | $object; |
102 | } |
103 | |
104 | sub create_class_with_roles { |
105 | my ($me, $superclass, @roles) = @_; |
106 | |
fb5074f6 |
107 | die "No roles supplied!" unless @roles; |
108 | |
c69190f1 |
109 | my $new_name = join( |
110 | '__WITH__', $superclass, my $compose_name = join '__AND__', @roles |
111 | ); |
112 | |
1947330a |
113 | return $new_name if $COMPOSED{class}{$new_name}; |
114 | |
115 | foreach my $role (@roles) { |
fb5074f6 |
116 | _load_module($role); |
29dde8ba |
117 | die "${role} is not a Role::Tiny" unless $INFO{$role}; |
1947330a |
118 | } |
119 | |
786e5ba0 |
120 | if ($] >= 5.010) { |
7568ba55 |
121 | require mro; |
b1eebd55 |
122 | } else { |
7568ba55 |
123 | require MRO::Compat; |
b1eebd55 |
124 | } |
1947330a |
125 | |
126 | my @composable = map $me->_composable_package_for($_), reverse @roles; |
127 | |
128 | *{_getglob("${new_name}::ISA")} = [ @composable, $superclass ]; |
129 | |
29dde8ba |
130 | my @info = map $INFO{$_}, @roles; |
1947330a |
131 | |
132 | $me->_check_requires( |
133 | $new_name, $compose_name, |
134 | do { my %h; @h{map @{$_->{requires}||[]}, @info} = (); keys %h } |
135 | ); |
1947330a |
136 | |
137 | *{_getglob "${new_name}::does"} = \&does_role unless $new_name->can('does'); |
138 | |
139 | @{$APPLIED_TO{$new_name}||={}}{ |
140 | map keys %{$APPLIED_TO{$_}}, @roles |
141 | } = (); |
142 | |
143 | $COMPOSED{class}{$new_name} = 1; |
144 | return $new_name; |
145 | } |
146 | |
60dfe768 |
147 | sub apply_union_of_roles_to_package { |
148 | my ($me, $to, @roles) = @_; |
149 | |
150 | return $me->apply_role_to_package($to, $roles[0]) if @roles == 1; |
151 | |
671b5a88 |
152 | my %conflicts = %{$me->_union_info_for(@roles)->{conflicts}}; |
153 | delete $conflicts{$_} for $me->_concrete_methods_of($to); |
154 | if (keys %conflicts) { |
60dfe768 |
155 | my $fail = |
156 | join "\n", |
671b5a88 |
157 | map { |
158 | "Due to a method name conflict between roles " |
159 | ."'".join(' and ', sort values %{$conflicts{$_}})."'" |
160 | .", the method '$_' must be implemented by '${to}'" |
161 | } keys %conflicts; |
162 | die $fail; |
60dfe768 |
163 | } |
164 | $me->apply_role_to_package($to, $_) for @roles; |
671b5a88 |
165 | $APPLIED_TO{$to}{join('|',@roles)} = 1; |
166 | } |
167 | |
168 | sub _union_info_for { |
169 | my ($me, @roles) = @_; |
170 | $UNION_INFO{join('|',@roles)} ||= do { |
171 | _load_module($_) for @roles; |
172 | my %methods; |
173 | foreach my $role (@roles) { |
174 | my $this_methods = $me->_concrete_methods_of($role); |
175 | $methods{$_}{$this_methods->{$_}} = $role for keys %$this_methods; |
176 | } |
177 | delete $methods{$_} for grep keys(%{$methods{$_}}) == 1, keys %methods; |
178 | +{ conflicts => \%methods } |
179 | }; |
60dfe768 |
180 | } |
181 | |
1947330a |
182 | sub _composable_package_for { |
183 | my ($me, $role) = @_; |
184 | my $composed_name = 'Role::Tiny::_COMPOSABLE::'.$role; |
185 | return $composed_name if $COMPOSED{role}{$composed_name}; |
186 | $me->_install_methods($composed_name, $role); |
187 | my $base_name = $composed_name.'::_BASE'; |
188 | *{_getglob("${composed_name}::ISA")} = [ $base_name ]; |
189 | my $modifiers = $INFO{$role}{modifiers}||[]; |
b1eebd55 |
190 | my @mod_base; |
1947330a |
191 | foreach my $modified ( |
192 | do { my %h; @h{map $_->[1], @$modifiers} = (); keys %h } |
193 | ) { |
b1eebd55 |
194 | push @mod_base, "sub ${modified} { shift->next::method(\@_) }"; |
1947330a |
195 | } |
385f5087 |
196 | my $e; |
59812c87 |
197 | { |
198 | local $@; |
199 | eval(my $code = join "\n", "package ${base_name};", @mod_base); |
385f5087 |
200 | $e = "Evaling failed: $@\nTrying to eval:\n${code}" if $@; |
59812c87 |
201 | } |
385f5087 |
202 | die $e if $e; |
1947330a |
203 | $me->_install_modifiers($composed_name, $modifiers); |
204 | $COMPOSED{role}{$composed_name} = 1; |
205 | return $composed_name; |
206 | } |
207 | |
208 | sub _check_requires { |
209 | my ($me, $to, $name, @requires) = @_; |
210 | if (my @requires_fail = grep !$to->can($_), @requires) { |
211 | # role -> role, add to requires, role -> class, error out |
212 | if (my $to_info = $INFO{$to}) { |
213 | push @{$to_info->{requires}||=[]}, @requires_fail; |
214 | } else { |
215 | die "Can't apply ${name} to ${to} - missing ".join(', ', @requires_fail); |
216 | } |
217 | } |
218 | } |
219 | |
4db3a740 |
220 | sub _concrete_methods_of { |
221 | my ($me, $role) = @_; |
1947330a |
222 | my $info = $INFO{$role}; |
60dfe768 |
223 | # grab role symbol table |
224 | my $stash = do { no strict 'refs'; \%{"${role}::"}}; |
225 | my $not_methods = $info->{not_methods}; |
226 | +{ |
227 | # grab all code entries that aren't in the not_methods list |
228 | map { |
229 | my $code = *{$stash->{$_}}{CODE}; |
230 | # rely on the '' key we added in import for "no code here" |
231 | exists $not_methods->{$code||''} ? () : ($_ => $code) |
232 | } grep !ref($stash->{$_}), keys %$stash |
ab3370e7 |
233 | }; |
4db3a740 |
234 | } |
235 | |
236 | sub methods_provided_by { |
237 | my ($me, $role) = @_; |
238 | die "${role} is not a Role::Tiny" unless my $info = $INFO{$role}; |
239 | (keys %{$me->_concrete_methods_of($role)}, @{$info->{requires}||[]}); |
240 | } |
241 | |
242 | sub _install_methods { |
243 | my ($me, $to, $role) = @_; |
244 | |
245 | my $info = $INFO{$role}; |
246 | |
247 | my $methods = $me->_concrete_methods_of($role); |
1947330a |
248 | |
ab3370e7 |
249 | # grab target symbol table |
250 | my $stash = do { no strict 'refs'; \%{"${to}::"}}; |
1947330a |
251 | |
ab3370e7 |
252 | # determine already extant methods of target |
253 | my %has_methods; |
254 | @has_methods{grep |
faa9ce11 |
255 | +(ref($stash->{$_}) || *{$stash->{$_}}{CODE}), |
ab3370e7 |
256 | keys %$stash |
257 | } = (); |
ab3370e7 |
258 | |
1947330a |
259 | foreach my $i (grep !exists $has_methods{$_}, keys %$methods) { |
ab3370e7 |
260 | no warnings 'once'; |
5a247406 |
261 | *{_getglob "${to}::${i}"} = $methods->{$i}; |
ab3370e7 |
262 | } |
1947330a |
263 | } |
ab3370e7 |
264 | |
1947330a |
265 | sub _install_modifiers { |
266 | my ($me, $to, $modifiers) = @_; |
dccea57d |
267 | if (my $info = $INFO{$to}) { |
268 | push @{$info->{modifiers}}, @{$modifiers||[]}; |
269 | } else { |
270 | foreach my $modifier (@{$modifiers||[]}) { |
271 | $me->_install_single_modifier($to, @$modifier); |
272 | } |
96d3f07a |
273 | } |
ab3370e7 |
274 | } |
275 | |
dccea57d |
276 | sub _install_single_modifier { |
277 | my ($me, @args) = @_; |
278 | Class::Method::Modifiers::install_modifier(@args); |
279 | } |
280 | |
ab3370e7 |
281 | sub does_role { |
390ac406 |
282 | my ($proto, $role) = @_; |
283 | return exists $APPLIED_TO{ref($proto)||$proto}{$role}; |
ab3370e7 |
284 | } |
285 | |
286 | 1; |
5febcf4d |
287 | |
0b6e5fff |
288 | =head1 NAME |
289 | |
70061353 |
290 | Role::Tiny - Roles. Like a nouvelle cuisine portion size slice of Moose. |
5febcf4d |
291 | |
292 | =head1 SYNOPSIS |
293 | |
294 | package Some::Role; |
295 | |
296 | use Role::Tiny; |
297 | |
298 | sub foo { ... } |
299 | |
300 | sub bar { ... } |
301 | |
adcb6c3d |
302 | around baz => sub { ... } |
303 | |
5febcf4d |
304 | 1; |
305 | |
306 | else where |
307 | |
308 | package Some::Class; |
309 | |
a1164a0b |
310 | use Role::Tiny::With; |
5febcf4d |
311 | |
312 | # bar gets imported, but not foo |
a1164a0b |
313 | with 'Some::Role'; |
5febcf4d |
314 | |
315 | sub foo { ... } |
316 | |
adcb6c3d |
317 | # baz is wrapped in the around modifier by Class::Method::Modifiers |
318 | sub baz { ... } |
319 | |
5febcf4d |
320 | 1; |
321 | |
adcb6c3d |
322 | If you wanted attributes as well, look at L<Moo::Role>. |
323 | |
5febcf4d |
324 | =head1 DESCRIPTION |
325 | |
326 | C<Role::Tiny> is a minimalist role composition tool. |
327 | |
328 | =head1 ROLE COMPOSITION |
329 | |
330 | Role composition can be thought of as much more clever and meaningful multiple |
331 | inheritance. The basics of this implementation of roles is: |
332 | |
333 | =over 2 |
334 | |
335 | =item * |
336 | |
337 | If a method is already defined on a class, that method will not be composed in |
338 | from the role. |
339 | |
340 | =item * |
341 | |
342 | If a method that the role L</requires> to be implemented is not implemented, |
343 | role application will fail loudly. |
344 | |
0d39f9d3 |
345 | =back |
346 | |
5febcf4d |
347 | Unlike L<Class::C3>, where the B<last> class inherited from "wins," role |
348 | composition is the other way around, where first wins. In a more complete |
349 | system (see L<Moose>) roles are checked to see if they clash. The goal of this |
350 | is to be much simpler, hence disallowing composition of multiple roles at once. |
351 | |
352 | =head1 METHODS |
353 | |
354 | =head2 apply_role_to_package |
355 | |
369a4c50 |
356 | Role::Tiny->apply_role_to_package('Some::Package', 'Some::Role'); |
5febcf4d |
357 | |
a1164a0b |
358 | Composes role with package. See also L<Role::Tiny::With>. |
5febcf4d |
359 | |
360 | =head2 apply_roles_to_object |
361 | |
362 | Role::Tiny->apply_roles_to_object($foo, qw(Some::Role1 Some::Role2)); |
363 | |
364 | Composes roles in order into object directly. Object is reblessed into the |
365 | resulting class. |
366 | |
367 | =head2 create_class_with_roles |
368 | |
369 | Role::Tiny->create_class_with_roles('Some::Base', qw(Some::Role1 Some::Role2)); |
370 | |
371 | Creates a new class based on base, with the roles composed into it in order. |
372 | New class is returned. |
373 | |
54e4000d |
374 | =head1 SUBROUTINES |
5febcf4d |
375 | |
376 | =head2 does_role |
377 | |
54e4000d |
378 | if (Role::Tiny::does_role($foo, 'Some::Role')) { |
5febcf4d |
379 | ... |
380 | } |
381 | |
382 | Returns true if class has been composed with role. |
383 | |
54e4000d |
384 | This subroutine is also installed as ->does on any class a Role::Tiny is |
385 | composed into unless that class already has an ->does method, so |
386 | |
e4aa82b1 |
387 | if ($foo->does('Some::Role')) { |
54e4000d |
388 | ... |
389 | } |
390 | |
391 | will work for classes but to test a role, one must use ::does_role directly |
392 | |
5febcf4d |
393 | =head1 IMPORTED SUBROUTINES |
394 | |
395 | =head2 requires |
396 | |
397 | requires qw(foo bar); |
398 | |
399 | Declares a list of methods that must be defined to compose role. |
400 | |
401 | =head2 with |
402 | |
403 | with 'Some::Role1'; |
404 | with 'Some::Role2'; |
405 | |
406 | Composes another role into the current role. Only one role may be composed in |
407 | at a time to allow the code to remain as simple as possible. |
408 | |
409 | =head2 before |
410 | |
411 | before foo => sub { ... }; |
412 | |
413 | See L<< Class::Method::Modifiers/before method(s) => sub { ... } >> for full |
414 | documentation. |
415 | |
adcb6c3d |
416 | Note that since you are not required to use method modifiers, |
417 | L<Class::Method::Modifiers> is lazily loaded and we do not declare it as |
418 | a dependency. If your L<Role::Tiny> role uses modifiers you must depend on |
419 | both L<Class::Method::Modifiers> and L<Role::Tiny>. |
420 | |
5febcf4d |
421 | =head2 around |
422 | |
423 | around foo => sub { ... }; |
424 | |
425 | See L<< Class::Method::Modifiers/around method(s) => sub { ... } >> for full |
426 | documentation. |
427 | |
adcb6c3d |
428 | Note that since you are not required to use method modifiers, |
429 | L<Class::Method::Modifiers> is lazily loaded and we do not declare it as |
430 | a dependency. If your L<Role::Tiny> role uses modifiers you must depend on |
431 | both L<Class::Method::Modifiers> and L<Role::Tiny>. |
432 | |
5febcf4d |
433 | =head2 after |
434 | |
435 | after foo => sub { ... }; |
436 | |
437 | See L<< Class::Method::Modifiers/after method(s) => sub { ... } >> for full |
438 | documentation. |
439 | |
adcb6c3d |
440 | Note that since you are not required to use method modifiers, |
441 | L<Class::Method::Modifiers> is lazily loaded and we do not declare it as |
442 | a dependency. If your L<Role::Tiny> role uses modifiers you must depend on |
443 | both L<Class::Method::Modifiers> and L<Role::Tiny>. |
444 | |
445 | =head1 SEE ALSO |
446 | |
447 | L<Role::Tiny> is the attribute-less subset of L<Moo::Role>; L<Moo::Role> is |
448 | a meta-protocol-less subset of the king of role systems, L<Moose::Role>. |
449 | |
450 | If you don't want method modifiers and do want to be forcibly restricted |
451 | to a single role application per class, Ovid's L<Role::Basic> exists. But |
452 | Stevan Little (the L<Moose> author) and I are both still convinced that |
453 | he's Doing It Wrong. |
454 | |
c334a5c1 |
455 | =head1 AUTHOR |
456 | |
457 | mst - Matt S. Trout (cpan:MSTROUT) <mst@shadowcat.co.uk> |
458 | |
459 | =head1 CONTRIBUTORS |
460 | |
461 | dg - David Leadbeater (cpan:DGL) <dgl@dgl.cx> |
462 | |
463 | frew - Arthur Axel "fREW" Schmidt (cpan:FREW) <frioux@gmail.com> |
464 | |
465 | hobbs - Andrew Rodland (cpan:ARODLAND) <arodland@cpan.org> |
466 | |
467 | jnap - John Napiorkowski (cpan:JJNAPIORK) <jjn1056@yahoo.com> |
468 | |
469 | ribasushi - Peter Rabbitson (cpan:RIBASUSHI) <ribasushi@cpan.org> |
470 | |
471 | chip - Chip Salzenberg (cpan:CHIPS) <chip@pobox.com> |
472 | |
473 | ajgb - Alex J. G. BurzyĆski (cpan:AJGB) <ajgb@cpan.org> |
474 | |
475 | doy - Jesse Luehrs (cpan:DOY) <doy at tozt dot net> |
476 | |
477 | perigrin - Chris Prather (cpan:PERIGRIN) <chris@prather.org> |
478 | |
479 | =head1 COPYRIGHT |
40f3e3aa |
480 | |
c334a5c1 |
481 | Copyright (c) 2010-2012 the Role::Tiny L</AUTHOR> and L</CONTRIBUTORS> |
482 | as listed above. |
40f3e3aa |
483 | |
c334a5c1 |
484 | =head1 LICENSE |
40f3e3aa |
485 | |
c334a5c1 |
486 | This library is free software and may be distributed under the same terms |
487 | as perl itself. |
40f3e3aa |
488 | |
489 | =cut |