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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 | |
9 | our %INFO; |
10 | our %APPLIED_TO; |
1947330a |
11 | our %COMPOSED; |
ab3370e7 |
12 | |
5e03b55c |
13 | # inlined from Moo::_Utils - update that first. |
14 | |
fb5074f6 |
15 | sub _load_module { |
fb5074f6 |
16 | (my $proto = $_[0]) =~ s/::/\//g; |
5e03b55c |
17 | return 1 if $INC{"${proto}.pm"}; |
18 | # can't just ->can('can') because a sub-package Foo::Bar::Baz |
19 | # creates a 'Baz::' key in Foo::Bar's symbol table |
20 | return 1 if grep !/::$/, keys %{_getstash($_[0])||{}}; |
fb5074f6 |
21 | require "${proto}.pm"; |
22 | return 1; |
23 | } |
24 | |
ab3370e7 |
25 | sub import { |
26 | my $target = caller; |
a1164a0b |
27 | my $me = shift; |
de3d4906 |
28 | strictures->import; |
1ba11455 |
29 | return if $INFO{$target}; # already exported into this package |
ab3370e7 |
30 | # get symbol table reference |
31 | my $stash = do { no strict 'refs'; \%{"${target}::"} }; |
32 | # install before/after/around subs |
33 | foreach my $type (qw(before after around)) { |
5a247406 |
34 | *{_getglob "${target}::${type}"} = sub { |
b1eebd55 |
35 | require Class::Method::Modifiers; |
ab3370e7 |
36 | push @{$INFO{$target}{modifiers}||=[]}, [ $type => @_ ]; |
37 | }; |
38 | } |
5a247406 |
39 | *{_getglob "${target}::requires"} = sub { |
ab3370e7 |
40 | push @{$INFO{$target}{requires}||=[]}, @_; |
41 | }; |
5a247406 |
42 | *{_getglob "${target}::with"} = sub { |
43 | die "Only one role supported at a time by with" if @_ > 1; |
369a4c50 |
44 | $me->apply_role_to_package($target, $_[0]); |
96d3f07a |
45 | }; |
ab3370e7 |
46 | # grab all *non-constant* (ref eq 'SCALAR') subs present |
47 | # in the symbol table and store their refaddrs (no need to forcibly |
48 | # inflate constant subs into real subs) - also add '' to here (this |
49 | # is used later) |
50 | @{$INFO{$target}{not_methods}={}}{ |
51 | '', map { *$_{CODE}||() } grep !(ref eq 'SCALAR'), values %$stash |
52 | } = (); |
53 | # a role does itself |
54 | $APPLIED_TO{$target} = { $target => undef }; |
55 | } |
56 | |
57 | sub apply_role_to_package { |
369a4c50 |
58 | my ($me, $to, $role) = @_; |
1947330a |
59 | |
fb5074f6 |
60 | _load_module($role); |
61 | |
ab3370e7 |
62 | die "This is apply_role_to_package" if ref($to); |
1947330a |
63 | die "${role} is not a Role::Tiny" unless my $info = $INFO{$role}; |
64 | |
65 | $me->_check_requires($to, $role, @{$info->{requires}||[]}); |
66 | |
67 | $me->_install_methods($to, $role); |
68 | |
69 | $me->_install_modifiers($to, $info->{modifiers}); |
70 | |
71 | # only add does() method to classes and only if they don't have one |
72 | if (not $INFO{$to} and not $to->can('does')) { |
73 | *{_getglob "${to}::does"} = \&does_role; |
74 | } |
75 | |
1947330a |
76 | # copy our role list into the target's |
77 | @{$APPLIED_TO{$to}||={}}{keys %{$APPLIED_TO{$role}}} = (); |
78 | } |
79 | |
80 | sub apply_roles_to_object { |
81 | my ($me, $object, @roles) = @_; |
82 | die "No roles supplied!" unless @roles; |
83 | my $class = ref($object); |
84 | bless($object, $me->create_class_with_roles($class, @roles)); |
85 | $object; |
86 | } |
87 | |
88 | sub create_class_with_roles { |
89 | my ($me, $superclass, @roles) = @_; |
90 | |
fb5074f6 |
91 | die "No roles supplied!" unless @roles; |
92 | |
c69190f1 |
93 | my $new_name = join( |
94 | '__WITH__', $superclass, my $compose_name = join '__AND__', @roles |
95 | ); |
96 | |
1947330a |
97 | return $new_name if $COMPOSED{class}{$new_name}; |
98 | |
99 | foreach my $role (@roles) { |
fb5074f6 |
100 | _load_module($role); |
1947330a |
101 | die "${role} is not a Role::Tiny" unless my $info = $INFO{$role}; |
102 | } |
103 | |
786e5ba0 |
104 | if ($] >= 5.010) { |
b1eebd55 |
105 | require mro; |
106 | } else { |
107 | require MRO::Compat; |
108 | } |
1947330a |
109 | |
110 | my @composable = map $me->_composable_package_for($_), reverse @roles; |
111 | |
112 | *{_getglob("${new_name}::ISA")} = [ @composable, $superclass ]; |
113 | |
114 | my @info = map +($INFO{$_} ? $INFO{$_} : ()), @roles; |
115 | |
116 | $me->_check_requires( |
117 | $new_name, $compose_name, |
118 | do { my %h; @h{map @{$_->{requires}||[]}, @info} = (); keys %h } |
119 | ); |
1947330a |
120 | |
121 | *{_getglob "${new_name}::does"} = \&does_role unless $new_name->can('does'); |
122 | |
123 | @{$APPLIED_TO{$new_name}||={}}{ |
124 | map keys %{$APPLIED_TO{$_}}, @roles |
125 | } = (); |
126 | |
127 | $COMPOSED{class}{$new_name} = 1; |
128 | return $new_name; |
129 | } |
130 | |
131 | sub _composable_package_for { |
132 | my ($me, $role) = @_; |
133 | my $composed_name = 'Role::Tiny::_COMPOSABLE::'.$role; |
134 | return $composed_name if $COMPOSED{role}{$composed_name}; |
135 | $me->_install_methods($composed_name, $role); |
136 | my $base_name = $composed_name.'::_BASE'; |
137 | *{_getglob("${composed_name}::ISA")} = [ $base_name ]; |
138 | my $modifiers = $INFO{$role}{modifiers}||[]; |
b1eebd55 |
139 | my @mod_base; |
1947330a |
140 | foreach my $modified ( |
141 | do { my %h; @h{map $_->[1], @$modifiers} = (); keys %h } |
142 | ) { |
b1eebd55 |
143 | push @mod_base, "sub ${modified} { shift->next::method(\@_) }"; |
1947330a |
144 | } |
b1eebd55 |
145 | eval(my $code = join "\n", "package ${base_name};", @mod_base); |
146 | die "Evaling failed: $@\nTrying to eval:\n${code}" if $@; |
1947330a |
147 | $me->_install_modifiers($composed_name, $modifiers); |
148 | $COMPOSED{role}{$composed_name} = 1; |
149 | return $composed_name; |
150 | } |
151 | |
152 | sub _check_requires { |
153 | my ($me, $to, $name, @requires) = @_; |
154 | if (my @requires_fail = grep !$to->can($_), @requires) { |
155 | # role -> role, add to requires, role -> class, error out |
156 | if (my $to_info = $INFO{$to}) { |
157 | push @{$to_info->{requires}||=[]}, @requires_fail; |
158 | } else { |
159 | die "Can't apply ${name} to ${to} - missing ".join(', ', @requires_fail); |
160 | } |
161 | } |
162 | } |
163 | |
4db3a740 |
164 | sub _concrete_methods_of { |
165 | my ($me, $role) = @_; |
1947330a |
166 | my $info = $INFO{$role}; |
4db3a740 |
167 | $info->{methods} ||= do { |
ab3370e7 |
168 | # grab role symbol table |
169 | my $stash = do { no strict 'refs'; \%{"${role}::"}}; |
170 | my $not_methods = $info->{not_methods}; |
171 | +{ |
172 | # grab all code entries that aren't in the not_methods list |
173 | map { |
934ea2c1 |
174 | my $code = *{$stash->{$_}}{CODE}; |
175 | # rely on the '' key we added in import for "no code here" |
176 | exists $not_methods->{$code||''} ? () : ($_ => $code) |
ab3370e7 |
177 | } grep !(ref($stash->{$_}) eq 'SCALAR'), keys %$stash |
178 | }; |
179 | }; |
4db3a740 |
180 | } |
181 | |
182 | sub methods_provided_by { |
183 | my ($me, $role) = @_; |
184 | die "${role} is not a Role::Tiny" unless my $info = $INFO{$role}; |
185 | (keys %{$me->_concrete_methods_of($role)}, @{$info->{requires}||[]}); |
186 | } |
187 | |
188 | sub _install_methods { |
189 | my ($me, $to, $role) = @_; |
190 | |
191 | my $info = $INFO{$role}; |
192 | |
193 | my $methods = $me->_concrete_methods_of($role); |
1947330a |
194 | |
ab3370e7 |
195 | # grab target symbol table |
196 | my $stash = do { no strict 'refs'; \%{"${to}::"}}; |
1947330a |
197 | |
ab3370e7 |
198 | # determine already extant methods of target |
199 | my %has_methods; |
200 | @has_methods{grep |
201 | +((ref($stash->{$_}) eq 'SCALAR') || (*{$stash->{$_}}{CODE})), |
202 | keys %$stash |
203 | } = (); |
ab3370e7 |
204 | |
1947330a |
205 | foreach my $i (grep !exists $has_methods{$_}, keys %$methods) { |
ab3370e7 |
206 | no warnings 'once'; |
5a247406 |
207 | *{_getglob "${to}::${i}"} = $methods->{$i}; |
ab3370e7 |
208 | } |
1947330a |
209 | } |
ab3370e7 |
210 | |
1947330a |
211 | sub _install_modifiers { |
212 | my ($me, $to, $modifiers) = @_; |
dccea57d |
213 | if (my $info = $INFO{$to}) { |
214 | push @{$info->{modifiers}}, @{$modifiers||[]}; |
215 | } else { |
216 | foreach my $modifier (@{$modifiers||[]}) { |
217 | $me->_install_single_modifier($to, @$modifier); |
218 | } |
96d3f07a |
219 | } |
ab3370e7 |
220 | } |
221 | |
dccea57d |
222 | sub _install_single_modifier { |
223 | my ($me, @args) = @_; |
224 | Class::Method::Modifiers::install_modifier(@args); |
225 | } |
226 | |
ab3370e7 |
227 | sub does_role { |
390ac406 |
228 | my ($proto, $role) = @_; |
229 | return exists $APPLIED_TO{ref($proto)||$proto}{$role}; |
ab3370e7 |
230 | } |
231 | |
232 | 1; |
5febcf4d |
233 | |
0b6e5fff |
234 | =head1 NAME |
235 | |
236 | Role::Tiny - Roles. Like a nouvelle cusine portion size slice of Moose. |
5febcf4d |
237 | |
238 | =head1 SYNOPSIS |
239 | |
240 | package Some::Role; |
241 | |
242 | use Role::Tiny; |
243 | |
244 | sub foo { ... } |
245 | |
246 | sub bar { ... } |
247 | |
248 | 1; |
249 | |
250 | else where |
251 | |
252 | package Some::Class; |
253 | |
a1164a0b |
254 | use Role::Tiny::With; |
5febcf4d |
255 | |
256 | # bar gets imported, but not foo |
a1164a0b |
257 | with 'Some::Role'; |
5febcf4d |
258 | |
259 | sub foo { ... } |
260 | |
261 | 1; |
262 | |
263 | =head1 DESCRIPTION |
264 | |
265 | C<Role::Tiny> is a minimalist role composition tool. |
266 | |
267 | =head1 ROLE COMPOSITION |
268 | |
269 | Role composition can be thought of as much more clever and meaningful multiple |
270 | inheritance. The basics of this implementation of roles is: |
271 | |
272 | =over 2 |
273 | |
274 | =item * |
275 | |
276 | If a method is already defined on a class, that method will not be composed in |
277 | from the role. |
278 | |
279 | =item * |
280 | |
281 | If a method that the role L</requires> to be implemented is not implemented, |
282 | role application will fail loudly. |
283 | |
0d39f9d3 |
284 | =back |
285 | |
5febcf4d |
286 | Unlike L<Class::C3>, where the B<last> class inherited from "wins," role |
287 | composition is the other way around, where first wins. In a more complete |
288 | system (see L<Moose>) roles are checked to see if they clash. The goal of this |
289 | is to be much simpler, hence disallowing composition of multiple roles at once. |
290 | |
291 | =head1 METHODS |
292 | |
293 | =head2 apply_role_to_package |
294 | |
369a4c50 |
295 | Role::Tiny->apply_role_to_package('Some::Package', 'Some::Role'); |
5febcf4d |
296 | |
a1164a0b |
297 | Composes role with package. See also L<Role::Tiny::With>. |
5febcf4d |
298 | |
299 | =head2 apply_roles_to_object |
300 | |
301 | Role::Tiny->apply_roles_to_object($foo, qw(Some::Role1 Some::Role2)); |
302 | |
303 | Composes roles in order into object directly. Object is reblessed into the |
304 | resulting class. |
305 | |
306 | =head2 create_class_with_roles |
307 | |
308 | Role::Tiny->create_class_with_roles('Some::Base', qw(Some::Role1 Some::Role2)); |
309 | |
310 | Creates a new class based on base, with the roles composed into it in order. |
311 | New class is returned. |
312 | |
54e4000d |
313 | =head1 SUBROUTINES |
5febcf4d |
314 | |
315 | =head2 does_role |
316 | |
54e4000d |
317 | if (Role::Tiny::does_role($foo, 'Some::Role')) { |
5febcf4d |
318 | ... |
319 | } |
320 | |
321 | Returns true if class has been composed with role. |
322 | |
54e4000d |
323 | This subroutine is also installed as ->does on any class a Role::Tiny is |
324 | composed into unless that class already has an ->does method, so |
325 | |
326 | if ($foo->does_role('Some::Role')) { |
327 | ... |
328 | } |
329 | |
330 | will work for classes but to test a role, one must use ::does_role directly |
331 | |
5febcf4d |
332 | =head1 IMPORTED SUBROUTINES |
333 | |
334 | =head2 requires |
335 | |
336 | requires qw(foo bar); |
337 | |
338 | Declares a list of methods that must be defined to compose role. |
339 | |
340 | =head2 with |
341 | |
342 | with 'Some::Role1'; |
343 | with 'Some::Role2'; |
344 | |
345 | Composes another role into the current role. Only one role may be composed in |
346 | at a time to allow the code to remain as simple as possible. |
347 | |
348 | =head2 before |
349 | |
350 | before foo => sub { ... }; |
351 | |
352 | See L<< Class::Method::Modifiers/before method(s) => sub { ... } >> for full |
353 | documentation. |
354 | |
355 | =head2 around |
356 | |
357 | around foo => sub { ... }; |
358 | |
359 | See L<< Class::Method::Modifiers/around method(s) => sub { ... } >> for full |
360 | documentation. |
361 | |
362 | =head2 after |
363 | |
364 | after foo => sub { ... }; |
365 | |
366 | See L<< Class::Method::Modifiers/after method(s) => sub { ... } >> for full |
367 | documentation. |
368 | |
40f3e3aa |
369 | =head1 AUTHORS |
370 | |
371 | See L<Moo> for authors. |
372 | |
373 | =head1 COPYRIGHT AND LICENSE |
374 | |
375 | See L<Moo> for the copyright and license. |
376 | |
377 | =cut |