Commit | Line | Data |
ab3370e7 |
1 | package Role::Tiny; |
2 | |
119014a7 |
3 | sub _getglob { \*{$_[0]} } |
4 | |
b1eebd55 |
5 | use strict; |
6 | use warnings FATAL => 'all'; |
ab3370e7 |
7 | |
8 | our %INFO; |
9 | our %APPLIED_TO; |
1947330a |
10 | our %COMPOSED; |
ab3370e7 |
11 | |
fb5074f6 |
12 | sub _load_module { |
13 | return 1 if $_[0]->can('can'); |
14 | (my $proto = $_[0]) =~ s/::/\//g; |
15 | require "${proto}.pm"; |
16 | return 1; |
17 | } |
18 | |
ab3370e7 |
19 | sub import { |
20 | my $target = caller; |
b1eebd55 |
21 | my $me = $_[0]; |
de3d4906 |
22 | strictures->import; |
1ba11455 |
23 | return if $INFO{$target}; # already exported into this package |
ab3370e7 |
24 | # get symbol table reference |
25 | my $stash = do { no strict 'refs'; \%{"${target}::"} }; |
26 | # install before/after/around subs |
27 | foreach my $type (qw(before after around)) { |
5a247406 |
28 | *{_getglob "${target}::${type}"} = sub { |
b1eebd55 |
29 | require Class::Method::Modifiers; |
ab3370e7 |
30 | push @{$INFO{$target}{modifiers}||=[]}, [ $type => @_ ]; |
31 | }; |
32 | } |
5a247406 |
33 | *{_getglob "${target}::requires"} = sub { |
ab3370e7 |
34 | push @{$INFO{$target}{requires}||=[]}, @_; |
35 | }; |
5a247406 |
36 | *{_getglob "${target}::with"} = sub { |
37 | die "Only one role supported at a time by with" if @_ > 1; |
369a4c50 |
38 | $me->apply_role_to_package($target, $_[0]); |
96d3f07a |
39 | }; |
ab3370e7 |
40 | # grab all *non-constant* (ref eq 'SCALAR') subs present |
41 | # in the symbol table and store their refaddrs (no need to forcibly |
42 | # inflate constant subs into real subs) - also add '' to here (this |
43 | # is used later) |
44 | @{$INFO{$target}{not_methods}={}}{ |
45 | '', map { *$_{CODE}||() } grep !(ref eq 'SCALAR'), values %$stash |
46 | } = (); |
47 | # a role does itself |
48 | $APPLIED_TO{$target} = { $target => undef }; |
49 | } |
50 | |
51 | sub apply_role_to_package { |
369a4c50 |
52 | my ($me, $to, $role) = @_; |
1947330a |
53 | |
fb5074f6 |
54 | _load_module($role); |
55 | |
ab3370e7 |
56 | die "This is apply_role_to_package" if ref($to); |
1947330a |
57 | die "${role} is not a Role::Tiny" unless my $info = $INFO{$role}; |
58 | |
59 | $me->_check_requires($to, $role, @{$info->{requires}||[]}); |
60 | |
61 | $me->_install_methods($to, $role); |
62 | |
63 | $me->_install_modifiers($to, $info->{modifiers}); |
64 | |
65 | # only add does() method to classes and only if they don't have one |
66 | if (not $INFO{$to} and not $to->can('does')) { |
67 | *{_getglob "${to}::does"} = \&does_role; |
68 | } |
69 | |
1947330a |
70 | # copy our role list into the target's |
71 | @{$APPLIED_TO{$to}||={}}{keys %{$APPLIED_TO{$role}}} = (); |
72 | } |
73 | |
74 | sub apply_roles_to_object { |
75 | my ($me, $object, @roles) = @_; |
76 | die "No roles supplied!" unless @roles; |
77 | my $class = ref($object); |
78 | bless($object, $me->create_class_with_roles($class, @roles)); |
79 | $object; |
80 | } |
81 | |
82 | sub create_class_with_roles { |
83 | my ($me, $superclass, @roles) = @_; |
84 | |
fb5074f6 |
85 | die "No roles supplied!" unless @roles; |
86 | |
1947330a |
87 | my $new_name = join('+', $superclass, my $compose_name = join '+', @roles); |
88 | return $new_name if $COMPOSED{class}{$new_name}; |
89 | |
90 | foreach my $role (@roles) { |
fb5074f6 |
91 | _load_module($role); |
1947330a |
92 | die "${role} is not a Role::Tiny" unless my $info = $INFO{$role}; |
93 | } |
94 | |
b1eebd55 |
95 | if ($] > 5.010) { |
96 | require mro; |
97 | } else { |
98 | require MRO::Compat; |
99 | } |
1947330a |
100 | |
101 | my @composable = map $me->_composable_package_for($_), reverse @roles; |
102 | |
103 | *{_getglob("${new_name}::ISA")} = [ @composable, $superclass ]; |
104 | |
105 | my @info = map +($INFO{$_} ? $INFO{$_} : ()), @roles; |
106 | |
107 | $me->_check_requires( |
108 | $new_name, $compose_name, |
109 | do { my %h; @h{map @{$_->{requires}||[]}, @info} = (); keys %h } |
110 | ); |
1947330a |
111 | |
112 | *{_getglob "${new_name}::does"} = \&does_role unless $new_name->can('does'); |
113 | |
114 | @{$APPLIED_TO{$new_name}||={}}{ |
115 | map keys %{$APPLIED_TO{$_}}, @roles |
116 | } = (); |
117 | |
118 | $COMPOSED{class}{$new_name} = 1; |
119 | return $new_name; |
120 | } |
121 | |
122 | sub _composable_package_for { |
123 | my ($me, $role) = @_; |
124 | my $composed_name = 'Role::Tiny::_COMPOSABLE::'.$role; |
125 | return $composed_name if $COMPOSED{role}{$composed_name}; |
126 | $me->_install_methods($composed_name, $role); |
127 | my $base_name = $composed_name.'::_BASE'; |
128 | *{_getglob("${composed_name}::ISA")} = [ $base_name ]; |
129 | my $modifiers = $INFO{$role}{modifiers}||[]; |
b1eebd55 |
130 | my @mod_base; |
1947330a |
131 | foreach my $modified ( |
132 | do { my %h; @h{map $_->[1], @$modifiers} = (); keys %h } |
133 | ) { |
b1eebd55 |
134 | push @mod_base, "sub ${modified} { shift->next::method(\@_) }"; |
1947330a |
135 | } |
b1eebd55 |
136 | eval(my $code = join "\n", "package ${base_name};", @mod_base); |
137 | die "Evaling failed: $@\nTrying to eval:\n${code}" if $@; |
1947330a |
138 | $me->_install_modifiers($composed_name, $modifiers); |
139 | $COMPOSED{role}{$composed_name} = 1; |
140 | return $composed_name; |
141 | } |
142 | |
143 | sub _check_requires { |
144 | my ($me, $to, $name, @requires) = @_; |
145 | if (my @requires_fail = grep !$to->can($_), @requires) { |
146 | # role -> role, add to requires, role -> class, error out |
147 | if (my $to_info = $INFO{$to}) { |
148 | push @{$to_info->{requires}||=[]}, @requires_fail; |
149 | } else { |
150 | die "Can't apply ${name} to ${to} - missing ".join(', ', @requires_fail); |
151 | } |
152 | } |
153 | } |
154 | |
4db3a740 |
155 | sub _concrete_methods_of { |
156 | my ($me, $role) = @_; |
1947330a |
157 | my $info = $INFO{$role}; |
4db3a740 |
158 | $info->{methods} ||= do { |
ab3370e7 |
159 | # grab role symbol table |
160 | my $stash = do { no strict 'refs'; \%{"${role}::"}}; |
161 | my $not_methods = $info->{not_methods}; |
162 | +{ |
163 | # grab all code entries that aren't in the not_methods list |
164 | map { |
934ea2c1 |
165 | my $code = *{$stash->{$_}}{CODE}; |
166 | # rely on the '' key we added in import for "no code here" |
167 | exists $not_methods->{$code||''} ? () : ($_ => $code) |
ab3370e7 |
168 | } grep !(ref($stash->{$_}) eq 'SCALAR'), keys %$stash |
169 | }; |
170 | }; |
4db3a740 |
171 | } |
172 | |
173 | sub methods_provided_by { |
174 | my ($me, $role) = @_; |
175 | die "${role} is not a Role::Tiny" unless my $info = $INFO{$role}; |
176 | (keys %{$me->_concrete_methods_of($role)}, @{$info->{requires}||[]}); |
177 | } |
178 | |
179 | sub _install_methods { |
180 | my ($me, $to, $role) = @_; |
181 | |
182 | my $info = $INFO{$role}; |
183 | |
184 | my $methods = $me->_concrete_methods_of($role); |
1947330a |
185 | |
ab3370e7 |
186 | # grab target symbol table |
187 | my $stash = do { no strict 'refs'; \%{"${to}::"}}; |
1947330a |
188 | |
ab3370e7 |
189 | # determine already extant methods of target |
190 | my %has_methods; |
191 | @has_methods{grep |
192 | +((ref($stash->{$_}) eq 'SCALAR') || (*{$stash->{$_}}{CODE})), |
193 | keys %$stash |
194 | } = (); |
ab3370e7 |
195 | |
1947330a |
196 | foreach my $i (grep !exists $has_methods{$_}, keys %$methods) { |
ab3370e7 |
197 | no warnings 'once'; |
5a247406 |
198 | *{_getglob "${to}::${i}"} = $methods->{$i}; |
ab3370e7 |
199 | } |
1947330a |
200 | } |
ab3370e7 |
201 | |
1947330a |
202 | sub _install_modifiers { |
203 | my ($me, $to, $modifiers) = @_; |
dccea57d |
204 | if (my $info = $INFO{$to}) { |
205 | push @{$info->{modifiers}}, @{$modifiers||[]}; |
206 | } else { |
207 | foreach my $modifier (@{$modifiers||[]}) { |
208 | $me->_install_single_modifier($to, @$modifier); |
209 | } |
96d3f07a |
210 | } |
ab3370e7 |
211 | } |
212 | |
dccea57d |
213 | sub _install_single_modifier { |
214 | my ($me, @args) = @_; |
215 | Class::Method::Modifiers::install_modifier(@args); |
216 | } |
217 | |
ab3370e7 |
218 | sub does_role { |
390ac406 |
219 | my ($proto, $role) = @_; |
220 | return exists $APPLIED_TO{ref($proto)||$proto}{$role}; |
ab3370e7 |
221 | } |
222 | |
223 | 1; |
5febcf4d |
224 | |
0b6e5fff |
225 | =head1 NAME |
226 | |
227 | Role::Tiny - Roles. Like a nouvelle cusine portion size slice of Moose. |
5febcf4d |
228 | |
229 | =head1 SYNOPSIS |
230 | |
231 | package Some::Role; |
232 | |
233 | use Role::Tiny; |
234 | |
235 | sub foo { ... } |
236 | |
237 | sub bar { ... } |
238 | |
239 | 1; |
240 | |
241 | else where |
242 | |
243 | package Some::Class; |
244 | |
245 | require Role::Tiny; |
246 | |
247 | # bar gets imported, but not foo |
248 | Role::Tiny->apply_role_to_package('Some::Role', __PACKAGE__); |
249 | |
250 | sub foo { ... } |
251 | |
252 | 1; |
253 | |
254 | =head1 DESCRIPTION |
255 | |
256 | C<Role::Tiny> is a minimalist role composition tool. |
257 | |
258 | =head1 ROLE COMPOSITION |
259 | |
260 | Role composition can be thought of as much more clever and meaningful multiple |
261 | inheritance. The basics of this implementation of roles is: |
262 | |
263 | =over 2 |
264 | |
265 | =item * |
266 | |
267 | If a method is already defined on a class, that method will not be composed in |
268 | from the role. |
269 | |
270 | =item * |
271 | |
272 | If a method that the role L</requires> to be implemented is not implemented, |
273 | role application will fail loudly. |
274 | |
275 | Unlike L<Class::C3>, where the B<last> class inherited from "wins," role |
276 | composition is the other way around, where first wins. In a more complete |
277 | system (see L<Moose>) roles are checked to see if they clash. The goal of this |
278 | is to be much simpler, hence disallowing composition of multiple roles at once. |
279 | |
280 | =head1 METHODS |
281 | |
282 | =head2 apply_role_to_package |
283 | |
369a4c50 |
284 | Role::Tiny->apply_role_to_package('Some::Package', 'Some::Role'); |
5febcf4d |
285 | |
286 | Composes role with package |
287 | |
288 | =head2 apply_roles_to_object |
289 | |
290 | Role::Tiny->apply_roles_to_object($foo, qw(Some::Role1 Some::Role2)); |
291 | |
292 | Composes roles in order into object directly. Object is reblessed into the |
293 | resulting class. |
294 | |
295 | =head2 create_class_with_roles |
296 | |
297 | Role::Tiny->create_class_with_roles('Some::Base', qw(Some::Role1 Some::Role2)); |
298 | |
299 | Creates a new class based on base, with the roles composed into it in order. |
300 | New class is returned. |
301 | |
54e4000d |
302 | =head1 SUBROUTINES |
5febcf4d |
303 | |
304 | =head2 does_role |
305 | |
54e4000d |
306 | if (Role::Tiny::does_role($foo, 'Some::Role')) { |
5febcf4d |
307 | ... |
308 | } |
309 | |
310 | Returns true if class has been composed with role. |
311 | |
54e4000d |
312 | This subroutine is also installed as ->does on any class a Role::Tiny is |
313 | composed into unless that class already has an ->does method, so |
314 | |
315 | if ($foo->does_role('Some::Role')) { |
316 | ... |
317 | } |
318 | |
319 | will work for classes but to test a role, one must use ::does_role directly |
320 | |
5febcf4d |
321 | =head1 IMPORTED SUBROUTINES |
322 | |
323 | =head2 requires |
324 | |
325 | requires qw(foo bar); |
326 | |
327 | Declares a list of methods that must be defined to compose role. |
328 | |
329 | =head2 with |
330 | |
331 | with 'Some::Role1'; |
332 | with 'Some::Role2'; |
333 | |
334 | Composes another role into the current role. Only one role may be composed in |
335 | at a time to allow the code to remain as simple as possible. |
336 | |
337 | =head2 before |
338 | |
339 | before foo => sub { ... }; |
340 | |
341 | See L<< Class::Method::Modifiers/before method(s) => sub { ... } >> for full |
342 | documentation. |
343 | |
344 | =head2 around |
345 | |
346 | around foo => sub { ... }; |
347 | |
348 | See L<< Class::Method::Modifiers/around method(s) => sub { ... } >> for full |
349 | documentation. |
350 | |
351 | =head2 after |
352 | |
353 | after foo => sub { ... }; |
354 | |
355 | See L<< Class::Method::Modifiers/after method(s) => sub { ... } >> for full |
356 | documentation. |
357 | |