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1 | package MRO::Compat; |
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2 | use strict; |
3 | use warnings; |
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4 | require 5.006_000; |
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5 | |
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6 | # Keep this < 1.00, so people can tell the fake |
7 | # mro.pm from the real one |
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8 | our $VERSION = '0.03'; |
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9 | |
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10 | BEGIN { |
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11 | # Alias our private functions over to |
12 | # the mro:: namespace and load |
13 | # Class::C3 if Perl < 5.9.5 |
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14 | if($] < 5.009_005) { |
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15 | $mro::VERSION # to fool Module::Install when generating META.yml |
16 | = $VERSION; |
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17 | $INC{'mro.pm'} = 'Faked by MRO::Compat'; |
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18 | *mro::import = \&__import; |
19 | *mro::get_linear_isa = \&__get_linear_isa; |
20 | *mro::set_mro = \&__set_mro; |
21 | *mro::get_mro = \&__get_mro; |
22 | *mro::get_isarev = \&__get_isarev; |
23 | *mro::is_universal = \&__is_universal; |
24 | *mro::method_changed_in = \&__method_changed_in; |
25 | *mro::invalidate_all_method_caches |
26 | = \&__invalidate_all_method_caches; |
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27 | require Class::C3; |
28 | if($Class::C3::XS::VERSION && $Class::C3::XS::VERSION > 0.03) { |
29 | *mro::get_pkg_gen = \&__get_pkg_gen_c3xs; |
30 | } |
31 | else { |
32 | *mro::get_pkg_gen = \&__get_pkg_gen_pp; |
33 | } |
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34 | } |
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35 | |
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36 | # Load mro.pm and provide no-op Class::C3::.*initialize() funcs for 5.9.5+ |
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37 | else { |
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38 | require mro; |
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39 | no warnings 'redefine'; |
40 | *Class::C3::initialize = sub { 1 }; |
41 | *Class::C3::reinitialize = sub { 1 }; |
42 | *Class::C3::uninitialize = sub { 1 }; |
43 | } |
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44 | } |
45 | |
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46 | =head1 NAME |
47 | |
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48 | MRO::Compat - mro::* interface compatibility for Perls < 5.9.5 |
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49 | |
50 | =head1 SYNOPSIS |
51 | |
52 | package FooClass; use base qw/X Y Z/; |
53 | package X; use base qw/ZZZ/; |
54 | package Y; use base qw/ZZZ/; |
55 | package Z; use base qw/ZZZ/; |
56 | |
57 | package main; |
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58 | use MRO::Compat; |
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59 | my $linear = mro::get_linear_isa('FooClass'); |
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60 | print join(q{, }, @$linear); |
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61 | |
62 | # Prints: "FooClass, X, ZZZ, Y, Z" |
63 | |
64 | =head1 DESCRIPTION |
65 | |
66 | The "mro" namespace provides several utilities for dealing |
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67 | with method resolution order and method caching in general |
68 | in Perl 5.9.5 and higher. |
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69 | |
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70 | This module provides those interfaces for |
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71 | earlier versions of Perl (back to 5.6.0 anyways). |
72 | |
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73 | It is a harmless no-op to use this module on 5.9.5+. If |
74 | you're writing a piece of software that would like to use |
75 | the parts of 5.9.5+'s mro:: interfaces that are supported |
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76 | here, and you want compatibility with older Perls, this |
77 | is the module for you. |
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78 | |
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79 | Some parts of this interface will work better with |
80 | L<Class::C3::XS> installed, but it's not a requirement. |
81 | |
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82 | This module never exports any functions. All calls must |
83 | be fully qualified with the C<mro::> prefix. |
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84 | |
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85 | The interface documentation here serves only as a quick |
86 | reference of what the function basically does, and what |
87 | differences between L<MRO::Compat> and 5.9.5+ one should |
88 | look out for. The main docs in 5.9.5's L<mro> are the real |
89 | interface docs, and contain a lot of other useful information. |
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90 | |
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91 | =head1 VERSION 0.02 |
92 | |
93 | This is the first release of this new module, and on top of that, |
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94 | the Perl 5.9.5 it seeks to provide compatibility with isn't even |
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95 | out yet. |
96 | |
97 | If you're going to use/depend on this, please keep abreast of |
98 | possible interface changes in the next few versions. Once Perl |
99 | 5.9.5 is out the door the interfaces should stabilize on whatever |
100 | 5.9.5 has to offer. In the meantime, don't be surprised if |
101 | L<MRO::Compat> and 5.9.5's interfaces aren't perfectly in sync |
102 | at all times. |
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103 | |
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104 | =head1 Functions |
105 | |
106 | =head2 mro::get_linear_isa($classname[, $type]) |
107 | |
108 | Returns an arrayref which is the linearized MRO of the given class. |
109 | Uses whichever MRO is currently in effect for that class by default, |
110 | or the given MRO (either C<c3> or C<dfs> if specified as C<$type>). |
111 | |
112 | The linearized MRO of a class is a single ordered list of all of the |
113 | classes that would be visited in the process of resolving a method |
114 | on the given class, starting with itself. It does not include any |
115 | duplicate entries. |
116 | |
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117 | Note that C<UNIVERSAL> (and any members of C<UNIVERSAL>'s MRO) are not |
118 | part of the MRO of a class, even though all classes implicitly inherit |
119 | methods from C<UNIVERSAL> and its parents. |
120 | |
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121 | =cut |
122 | |
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123 | sub __get_linear_isa_dfs { |
124 | no strict 'refs'; |
125 | |
126 | my $classname = shift; |
127 | |
128 | my @lin = ($classname); |
129 | my %stored; |
130 | foreach my $parent (@{"$classname\::ISA"}) { |
131 | my $plin = __get_linear_isa_dfs($parent); |
132 | foreach (@$plin) { |
133 | next if exists $stored{$_}; |
134 | push(@lin, $_); |
135 | $stored{$_} = 1; |
136 | } |
137 | } |
138 | return \@lin; |
139 | } |
140 | |
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141 | sub __get_linear_isa { |
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142 | my ($classname, $type) = @_; |
143 | die "mro::get_mro requires a classname" if !$classname; |
144 | |
145 | $type ||= __get_mro($classname); |
146 | if($type eq 'dfs') { |
147 | return __get_linear_isa_dfs($classname); |
148 | } |
149 | elsif($type eq 'c3') { |
150 | return [Class::C3::calculateMRO($classname)]; |
151 | } |
152 | die "type argument must be 'dfs' or 'c3'"; |
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153 | } |
154 | |
155 | =head2 mro::import |
156 | |
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157 | This allows the C<use mro 'dfs'> and |
158 | C<use mro 'c3'> syntaxes, providing you |
159 | L<use MRO::Compat> first. Please see the |
160 | L</USING C3> section for additional details. |
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161 | |
162 | =cut |
163 | |
164 | sub __import { |
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165 | if($_[1]) { |
166 | goto &Class::C3::import if $_[1] eq 'c3'; |
167 | __set_mro(scalar(caller), $_[1]); |
168 | } |
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169 | } |
170 | |
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171 | =head2 mro::set_mro($classname, $type) |
172 | |
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173 | Sets the mro of C<$classname> to one of the types |
174 | C<dfs> or C<c3>. Please see the L</USING C3> |
175 | section for additional details. |
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176 | |
177 | =cut |
178 | |
179 | sub __set_mro { |
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180 | my ($classname, $type) = @_; |
181 | if(!$classname || !$type) { |
182 | die q{Usage: mro::set_mro($classname, $type)}; |
183 | } |
184 | if($type eq 'c3') { |
185 | eval "package $classname; use Class::C3"; |
186 | die $@ if $@; |
187 | } |
188 | if($type ne 'dfs') { |
189 | die q{Invalid mro type "$type"}; |
190 | } |
191 | |
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192 | # In the dfs case, check whether we need to undo C3 |
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193 | if(defined $Class::C3::MRO{$classname}) { |
194 | Class::C3::_remove_method_dispatch_table($classname); |
195 | } |
196 | delete $Class::C3::MRO{$classname}; |
197 | |
198 | return; |
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199 | } |
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200 | |
201 | =head2 mro::get_mro($classname) |
202 | |
203 | Returns the MRO of the given class (either C<c3> or C<dfs>). |
204 | |
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205 | It considers any Class::C3-using class to have C3 MRO |
206 | even before L<Class::C3::initialize()> is called. |
207 | |
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208 | =cut |
209 | |
210 | sub __get_mro { |
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211 | my $classname = shift; |
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212 | die "mro::get_mro requires a classname" if !$classname; |
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213 | return 'c3' if exists $Class::C3::MRO{$classname}; |
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214 | return 'dfs'; |
215 | } |
216 | |
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217 | =head2 mro::get_isarev($classname) |
218 | |
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219 | Returns an arrayref of classes who are subclasses of the |
220 | given classname. In other words, classes who we exist, |
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221 | however indirectly, in the @ISA inheritancy hierarchy of. |
222 | |
223 | This is much slower on pre-5.9.5 Perls with MRO::Compat |
224 | than it is on 5.9.5+, as it has to search the entire |
225 | package namespace. |
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226 | |
227 | =cut |
228 | |
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229 | sub __get_all_pkgs_with_isas { |
230 | no strict 'refs'; |
231 | no warnings 'recursion'; |
232 | |
233 | my @retval; |
234 | |
235 | my $search = shift; |
236 | my $pfx; |
237 | my $isa; |
238 | if($search) { |
239 | $isa = \@{"$search\::ISA"}; |
240 | $pfx = "$search\::"; |
241 | } |
242 | else { |
243 | $search = 'main'; |
244 | $isa = \@main::ISA; |
245 | $pfx = ''; |
246 | } |
247 | |
248 | push(@retval, $search) if scalar(@$isa); |
249 | |
250 | foreach my $cand (keys %{"$search\::"}) { |
251 | if($cand =~ /::$/) { |
252 | $cand =~ s/::$//; |
253 | next if $cand eq $search; # skip self-reference (main?) |
254 | push(@retval, @{__get_all_pkgs_with_isas($pfx . $cand)}); |
255 | } |
256 | } |
257 | |
258 | return \@retval; |
259 | } |
260 | |
261 | sub __get_isarev_recurse { |
262 | no strict 'refs'; |
263 | |
264 | my ($class, $all_isas, $level) = @_; |
265 | |
266 | die "Recursive inheritance detected" if $level > 100; |
267 | |
268 | my %retval; |
269 | |
270 | foreach my $cand (@$all_isas) { |
271 | my $found_me; |
272 | foreach (@{"$cand\::ISA"}) { |
273 | if($_ eq $class) { |
274 | $found_me = 1; |
275 | last; |
276 | } |
277 | } |
278 | if($found_me) { |
279 | $retval{$cand} = 1; |
280 | map { $retval{$_} = 1 } |
281 | @{__get_isarev_recurse($cand, $all_isas, $level+1)}; |
282 | } |
283 | } |
284 | return [keys %retval]; |
285 | } |
286 | |
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287 | sub __get_isarev { |
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288 | my $classname = shift; |
289 | die "mro::get_isarev requires a classname" if !$classname; |
290 | |
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291 | __get_isarev_recurse($classname, __get_all_pkgs_with_isas(), 0); |
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292 | } |
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293 | |
294 | =head2 mro::is_universal($classname) |
295 | |
296 | Returns a boolean status indicating whether or not |
297 | the given classname is either C<UNIVERSAL> itself, |
298 | or one of C<UNIVERSAL>'s parents by C<@ISA> inheritance. |
299 | |
300 | Any class for which this function returns true is |
301 | "universal" in the sense that all classes potentially |
302 | inherit methods from it. |
303 | |
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304 | =cut |
305 | |
306 | sub __is_universal { |
307 | my $classname = shift; |
308 | die "mro::is_universal requires a classname" if !$classname; |
309 | |
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310 | my $lin = __get_linear_isa('UNIVERSAL'); |
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311 | foreach (@$lin) { |
312 | return 1 if $classname eq $_; |
313 | } |
314 | |
315 | return 0; |
316 | } |
317 | |
318 | =head2 mro::invalidate_all_method_caches |
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319 | |
320 | Increments C<PL_sub_generation>, which invalidates method |
321 | caching in all packages. |
322 | |
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323 | Please note that this is rarely necessary, unless you are |
324 | dealing with a situation which is known to confuse Perl's |
325 | method caching. |
326 | |
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327 | =cut |
328 | |
329 | sub __invalidate_all_method_caches { |
330 | # Super secret mystery code :) |
331 | @fedcba98::ISA = @fedcba98::ISA; |
332 | return; |
333 | } |
334 | |
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335 | =head2 mro::method_changed_in($classname) |
336 | |
337 | Invalidates the method cache of any classes dependent on the |
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338 | given class. In L<MRO::Compat> on pre-5.9.5 Perls, this is |
339 | an alias for C<mro::invalidate_all_method_caches> above, as |
340 | pre-5.9.5 Perls have no other way to do this. It will still |
341 | enforce the requirement that you pass it a classname, for |
342 | compatibility. |
343 | |
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344 | Please note that this is rarely necessary, unless you are |
345 | dealing with a situation which is known to confuse Perl's |
346 | method caching. |
347 | |
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348 | =cut |
349 | |
350 | sub __method_changed_in { |
351 | my $classname = shift; |
352 | die "mro::method_changed_in requires a classname" if !$classname; |
353 | |
354 | __invalidate_all_method_caches(); |
355 | } |
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356 | |
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357 | =head2 mro::get_pkg_gen($classname) |
358 | |
359 | Returns an integer which is incremented every time a local |
360 | method of or the C<@ISA> of the given package changes on |
361 | Perl 5.9.5+. On earlier Perls with this L<MRO::Compat> module, |
362 | it will probably increment a lot more often than necessary. |
363 | |
364 | =cut |
365 | |
366 | my $__pkg_gen = 2; |
367 | sub __get_pkg_gen_pp { |
368 | my $classname = shift; |
369 | die "mro::get_pkg_gen requires a classname" if !$classname; |
370 | return $__pkg_gen++; |
371 | } |
372 | |
373 | sub __get_pkg_gen_c3xs { |
374 | my $classname = shift; |
375 | die "mro::get_pkg_gen requires a classname" if !$classname; |
376 | |
377 | return Class::C3::XS::_plsubgen(); |
378 | } |
379 | |
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380 | =head1 USING C3 |
381 | |
382 | While this module makes the 5.9.5+ syntaxes |
383 | C<use mro 'c3'> and C<mro::set_mro("Foo", 'c3')> available |
384 | on older Perls, it does so merely by passing off the work |
385 | to L<Class::C3>. |
386 | |
387 | It does not remove the need for you to call |
388 | L<Class::C3>'s C<initialize()>, C<reinitialize()>, and/or |
389 | C<uninitialize()> at the appropriate times |
390 | as documented in the L<Class::C3> docs. |
391 | |
392 | Because L<MRO::Compat> has L<Class::C3> as a pre-requisite, |
393 | and requires it at C<use> time, you can blindly call |
394 | those functions in code that uses L<MRO::Compat>. |
395 | Under 5.9.5+ with L<MRO::Compat>, your calls to those |
396 | functions will become a no-op and everything will work fine. |
397 | |
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398 | =head1 SEE ALSO |
399 | |
400 | L<Class::C3> |
401 | |
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402 | L<mro> |
403 | |
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404 | =head1 AUTHOR |
405 | |
406 | Brandon L. Black, E<lt>blblack@gmail.comE<gt> |
407 | |
408 | =head1 COPYRIGHT AND LICENSE |
409 | |
410 | Copyright 2007 Brandon L. Black E<lt>blblack@gmail.comE<gt> |
411 | |
412 | This library is free software; you can redistribute it and/or modify |
413 | it under the same terms as Perl itself. |
414 | |
415 | =cut |
416 | |
417 | 1; |