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1 | package MRO::Compat; |
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2 | use strict; |
3 | use warnings; |
4 | |
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5 | our $VERSION = '0.01'; |
6 | |
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7 | # Is Class::C3 installed locally? |
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8 | our $C3_INSTALLED; |
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9 | |
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10 | BEGIN { |
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11 | # Don't do anything if 5.9.5+ |
12 | if($] < 5.009_005) { |
13 | # Find out if we have Class::C3 at all |
14 | eval { require Class::C3 }; |
15 | $C3_INSTALLED = 1 if !$@; |
16 | |
17 | # Alias our private functions over to |
18 | # the mro:: namespace |
19 | *mro::import = \&__import; |
20 | *mro::get_linear_isa = \&__get_linear_isa; |
21 | *mro::set_mro = \&__set_mro; |
22 | *mro::get_mro = \&__get_mro; |
23 | *mro::get_isarev = \&__get_isarev; |
24 | *mro::is_universal = \&__is_universal; |
25 | *mro::method_changed_in = \&__method_changed_in; |
26 | *mro::invalidate_all_method_caches |
27 | = \&__invalidate_all_method_caches; |
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28 | } |
29 | } |
30 | |
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31 | =head1 NAME |
32 | |
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33 | MRO::Compat - Partial mro::* interface compatibility for Perls < 5.9.5 |
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34 | |
35 | =head1 SYNOPSIS |
36 | |
37 | package FooClass; use base qw/X Y Z/; |
38 | package X; use base qw/ZZZ/; |
39 | package Y; use base qw/ZZZ/; |
40 | package Z; use base qw/ZZZ/; |
41 | |
42 | package main; |
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43 | use MRO::Compat; |
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44 | my $linear = mro::get_linear_isa('FooClass'); |
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45 | print join(q{, }, @$linear); |
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46 | |
47 | # Prints: "FooClass, X, ZZZ, Y, Z" |
48 | |
49 | =head1 DESCRIPTION |
50 | |
51 | The "mro" namespace provides several utilities for dealing |
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52 | with method resolution order and method caching in general |
53 | in Perl 5.9.5 and higher. |
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54 | |
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55 | This module provides a subset of those interfaces for |
56 | earlier versions of Perl. It is a harmless no-op to use |
57 | it on 5.9.5+. If you're writing a piece of software |
58 | that would like to use the parts of 5.9.5+'s mro:: |
59 | interfaces that are supported here, and you want |
60 | compatibility with older Perls, this is the module |
61 | for you. |
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62 | |
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63 | This module never exports any functions. All calls must |
64 | be fully qualified with the C<mro::> prefix. |
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65 | |
66 | =head1 Functions |
67 | |
68 | =head2 mro::get_linear_isa($classname[, $type]) |
69 | |
70 | Returns an arrayref which is the linearized MRO of the given class. |
71 | Uses whichever MRO is currently in effect for that class by default, |
72 | or the given MRO (either C<c3> or C<dfs> if specified as C<$type>). |
73 | |
74 | The linearized MRO of a class is a single ordered list of all of the |
75 | classes that would be visited in the process of resolving a method |
76 | on the given class, starting with itself. It does not include any |
77 | duplicate entries. |
78 | |
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79 | On pre-5.9.5 Perls with MRO::Compat, explicitly asking for the C<c3> |
80 | MRO of a class will die if L<Class::C3> is not installed. If |
81 | L<Class::C3> is installed, it will detect C3 classes and return the |
82 | correct C3 MRO unless explicitly asked to return the C<dfs> MRO. |
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83 | |
84 | Note that C<UNIVERSAL> (and any members of C<UNIVERSAL>'s MRO) are not |
85 | part of the MRO of a class, even though all classes implicitly inherit |
86 | methods from C<UNIVERSAL> and its parents. |
87 | |
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88 | =cut |
89 | |
90 | sub __get_linear_isa { |
91 | } |
92 | |
93 | =head2 mro::import |
94 | |
95 | Not supported, and hence 5.9.5's "use mro 'foo'" is also not supported. |
96 | These will die if used on pre-5.9.5 Perls. |
97 | |
98 | =cut |
99 | |
100 | sub __import { |
101 | die q{The "use mro 'foo'" is only supported on Perl 5.9.5+}; |
102 | } |
103 | |
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104 | =head2 mro::set_mro($classname, $type) |
105 | |
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106 | Not supported, will die if used on pre-5.9.5 Perls. |
107 | |
108 | =cut |
109 | |
110 | sub __set_mro { |
111 | die q{mro::set_mro() is only supported on Perl 5.9.5+}; |
112 | } |
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113 | |
114 | =head2 mro::get_mro($classname) |
115 | |
116 | Returns the MRO of the given class (either C<c3> or C<dfs>). |
117 | |
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118 | =cut |
119 | |
120 | sub __get_mro { |
121 | my $classname = shift |
122 | die "mro::get_mro requires a classname" if !$classname; |
123 | if($C3_INSTALLED && exists $Class::C3::MRO{$classname} |
124 | && $Class::C3::_initialized) { |
125 | return 'c3'; |
126 | } |
127 | return 'dfs'; |
128 | } |
129 | |
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130 | =head2 mro::get_isarev($classname) |
131 | |
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132 | Not supported, will die if used on pre-5.9.5 Perls. |
133 | |
134 | =cut |
135 | |
136 | sub __get_isarev { |
137 | die "mro::get_isarev() is only supported on Perl 5.9.5+"; |
138 | } |
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139 | |
140 | =head2 mro::is_universal($classname) |
141 | |
142 | Returns a boolean status indicating whether or not |
143 | the given classname is either C<UNIVERSAL> itself, |
144 | or one of C<UNIVERSAL>'s parents by C<@ISA> inheritance. |
145 | |
146 | Any class for which this function returns true is |
147 | "universal" in the sense that all classes potentially |
148 | inherit methods from it. |
149 | |
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150 | =cut |
151 | |
152 | sub __is_universal { |
153 | my $classname = shift; |
154 | die "mro::is_universal requires a classname" if !$classname; |
155 | |
156 | my $lin = __get_linear_isa($classname); |
157 | foreach (@$lin) { |
158 | return 1 if $classname eq $_; |
159 | } |
160 | |
161 | return 0; |
162 | } |
163 | |
164 | =head2 mro::invalidate_all_method_caches |
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165 | |
166 | Increments C<PL_sub_generation>, which invalidates method |
167 | caching in all packages. |
168 | |
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169 | =cut |
170 | |
171 | sub __invalidate_all_method_caches { |
172 | # Super secret mystery code :) |
173 | @fedcba98::ISA = @fedcba98::ISA; |
174 | return; |
175 | } |
176 | |
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177 | =head2 mro::method_changed_in($classname) |
178 | |
179 | Invalidates the method cache of any classes dependent on the |
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180 | given class. In L<MRO::Compat> on pre-5.9.5 Perls, this is |
181 | an alias for C<mro::invalidate_all_method_caches> above, as |
182 | pre-5.9.5 Perls have no other way to do this. It will still |
183 | enforce the requirement that you pass it a classname, for |
184 | compatibility. |
185 | |
186 | =cut |
187 | |
188 | sub __method_changed_in { |
189 | my $classname = shift; |
190 | die "mro::method_changed_in requires a classname" if !$classname; |
191 | |
192 | __invalidate_all_method_caches(); |
193 | } |
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194 | |
195 | =head1 SEE ALSO |
196 | |
197 | L<Class::C3> |
198 | |
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199 | L<mro> |
200 | |
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201 | =head1 AUTHOR |
202 | |
203 | Brandon L. Black, E<lt>blblack@gmail.comE<gt> |
204 | |
205 | =head1 COPYRIGHT AND LICENSE |
206 | |
207 | Copyright 2007 Brandon L. Black E<lt>blblack@gmail.comE<gt> |
208 | |
209 | This library is free software; you can redistribute it and/or modify |
210 | it under the same terms as Perl itself. |
211 | |
212 | =cut |
213 | |
214 | 1; |