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1 | package namespace::clean; |
2 | |
3 | =head1 NAME |
4 | |
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5 | namespace::clean - Keep imports and functions out of your namespace |
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6 | |
7 | =cut |
8 | |
9 | use warnings; |
10 | use strict; |
11 | |
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12 | use vars qw( $VERSION $STORAGE_VAR $SCOPE_HOOK_KEY $SCOPE_EXPLICIT ); |
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13 | use Symbol qw( qualify_to_ref ); |
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14 | use B::Hooks::EndOfScope; |
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15 | |
16 | =head1 VERSION |
17 | |
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18 | 0.11 |
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19 | |
20 | =cut |
21 | |
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22 | $VERSION = '0.11'; |
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23 | $STORAGE_VAR = '__NAMESPACE_CLEAN_STORAGE'; |
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24 | |
25 | =head1 SYNOPSIS |
26 | |
27 | package Foo; |
28 | use warnings; |
29 | use strict; |
30 | |
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31 | use Carp qw(croak); # 'croak' will be removed |
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32 | |
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33 | sub bar { 23 } # 'bar' will be removed |
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34 | |
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35 | # remove all previously defined functions |
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36 | use namespace::clean; |
37 | |
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38 | sub baz { bar() } # 'baz' still defined, 'bar' still bound |
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39 | |
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40 | # begin to collection function names from here again |
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41 | no namespace::clean; |
42 | |
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43 | sub quux { baz() } # 'quux' will be removed |
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44 | |
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45 | # remove all functions defined after the 'no' unimport |
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46 | use namespace::clean; |
47 | |
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48 | # Will print: 'No', 'No', 'Yes' and 'No' |
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49 | print +(__PACKAGE__->can('croak') ? 'Yes' : 'No'), "\n"; |
50 | print +(__PACKAGE__->can('bar') ? 'Yes' : 'No'), "\n"; |
51 | print +(__PACKAGE__->can('baz') ? 'Yes' : 'No'), "\n"; |
9b680ffe |
52 | print +(__PACKAGE__->can('quux') ? 'Yes' : 'No'), "\n"; |
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53 | |
54 | 1; |
55 | |
56 | =head1 DESCRIPTION |
57 | |
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58 | =head2 Keeping packages clean |
59 | |
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60 | When you define a function, or import one, into a Perl package, it will |
61 | naturally also be available as a method. This does not per se cause |
62 | problems, but it can complicate subclassing and, for example, plugin |
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63 | classes that are included via multiple inheritance by loading them as |
64 | base classes. |
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65 | |
66 | The C<namespace::clean> pragma will remove all previously declared or |
67 | imported symbols at the end of the current package's compile cycle. |
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68 | Functions called in the package itself will still be bound by their |
69 | name, but they won't show up as methods on your class or instances. |
70 | |
71 | By unimporting via C<no> you can tell C<namespace::clean> to start |
72 | collecting functions for the next C<use namespace::clean;> specification. |
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73 | |
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74 | You can use the C<-except> flag to tell C<namespace::clean> that you |
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75 | don't want it to remove a certain function or method. A common use would |
76 | be a module exporting an C<import> method along with some functions: |
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77 | |
78 | use ModuleExportingImport; |
79 | use namespace::clean -except => [qw( import )]; |
80 | |
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81 | If you just want to C<-except> a single sub, you can pass it directly. |
82 | For more than one value you have to use an array reference. |
83 | |
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84 | =head2 Explicitely removing functions when your scope is compiled |
85 | |
86 | It is also possible to explicitely tell C<namespace::clean> what packages |
87 | to remove when the surrounding scope has finished compiling. Here is an |
88 | example: |
89 | |
90 | package Foo; |
91 | use strict; |
92 | |
93 | # blessed NOT available |
94 | |
95 | sub my_class { |
96 | use Scalar::Util qw( blessed ); |
97 | use namespace::clean qw( blessed ); |
98 | |
99 | # blessed available |
100 | return blessed shift; |
101 | } |
102 | |
103 | # blessed NOT available |
104 | |
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105 | =head2 Moose |
106 | |
107 | When using C<namespace::clean> together with L<Moose> you want to keep |
108 | the installed C<meta> method. So your classes should look like: |
109 | |
110 | package Foo; |
111 | use Moose; |
112 | use namespace::clean -except => 'meta'; |
113 | ... |
114 | |
115 | Same goes for L<Moose::Role>. |
116 | |
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117 | =head2 Cleaning other packages |
118 | |
119 | You can tell C<namespace::clean> that you want to clean up another package |
120 | instead of the one importing. To do this you have to pass in the C<-cleanee> |
121 | option like this: |
122 | |
123 | package My::MooseX::namespace::clean; |
124 | use strict; |
125 | |
126 | use namespace::clean (); # no cleanup, just load |
127 | |
128 | sub import { |
129 | namespace::clean->import( |
130 | -cleanee => scalar(caller), |
131 | -except => 'meta', |
132 | ); |
133 | } |
134 | |
135 | If you don't care about C<namespace::clean>s discover-and-C<-except> logic, and |
136 | just want to remove subroutines, try L</clean_subroutines>. |
137 | |
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138 | =head1 METHODS |
139 | |
140 | You shouldn't need to call any of these. Just C<use> the package at the |
141 | appropriate place. |
142 | |
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143 | =cut |
144 | |
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145 | =head2 clean_subroutines |
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146 | |
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147 | This exposes the actual subroutine-removal logic. |
148 | |
149 | namespace::clean->clean_subroutines($cleanee, qw( subA subB )); |
150 | |
151 | will remove C<subA> and C<subB> from C<$cleanee>. Note that this will remove the |
152 | subroutines B<immediately> and not wait for scope end. If you want to have this |
153 | effect at a specific time (e.g. C<namespace::clean> acts on scope compile end) |
154 | it is your responsibility to make sure it runs at that time. |
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155 | |
156 | =cut |
157 | |
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158 | my $RemoveSubs = sub { |
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159 | |
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160 | my $cleanee = shift; |
161 | my $store = shift; |
162 | SYMBOL: |
163 | for my $f (@_) { |
164 | |
165 | # ignore already removed symbols |
166 | next SYMBOL if $store->{exclude}{ $f }; |
167 | no strict 'refs'; |
168 | |
169 | # keep original value to restore non-code slots |
170 | { no warnings 'uninitialized'; # fix possible unimports |
171 | local *__tmp = *{ ${ "${cleanee}::" }{ $f } }; |
172 | delete ${ "${cleanee}::" }{ $f }; |
173 | } |
174 | |
175 | SLOT: |
176 | # restore non-code slots to symbol |
177 | for my $t (qw( SCALAR ARRAY HASH IO FORMAT )) { |
178 | next SLOT unless defined *__tmp{ $t }; |
179 | *{ "${cleanee}::$f" } = *__tmp{ $t }; |
180 | } |
181 | } |
182 | }; |
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183 | |
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184 | sub clean_subroutines { |
185 | my ($nc, $cleanee, @subs) = @_; |
186 | $RemoveSubs->($cleanee, {}, @subs); |
187 | } |
188 | |
189 | =head2 import |
190 | |
191 | Makes a snapshot of the current defined functions and installs a |
192 | L<B::Hooks::EndOfScope> hook in the current scope to invoke the cleanups. |
193 | |
194 | =cut |
195 | |
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196 | sub import { |
197 | my ($pragma, @args) = @_; |
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198 | |
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199 | my (%args, $is_explicit); |
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200 | |
201 | ARG: |
202 | while (@args) { |
203 | |
204 | if ($args[0] =~ /^\-/) { |
205 | my $key = shift @args; |
206 | my $value = shift @args; |
207 | $args{ $key } = $value; |
208 | } |
209 | else { |
210 | $is_explicit++; |
211 | last ARG; |
212 | } |
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213 | } |
214 | |
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215 | my $cleanee = exists $args{ -cleanee } ? $args{ -cleanee } : scalar caller; |
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216 | if ($is_explicit) { |
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217 | on_scope_end { |
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218 | $RemoveSubs->($cleanee, {}, @args); |
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219 | }; |
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220 | } |
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221 | else { |
222 | |
223 | # calling class, all current functions and our storage |
224 | my $functions = $pragma->get_functions($cleanee); |
225 | my $store = $pragma->get_class_store($cleanee); |
226 | |
227 | # except parameter can be array ref or single value |
228 | my %except = map {( $_ => 1 )} ( |
229 | $args{ -except } |
230 | ? ( ref $args{ -except } eq 'ARRAY' ? @{ $args{ -except } } : $args{ -except } ) |
231 | : () |
232 | ); |
233 | |
234 | # register symbols for removal, if they have a CODE entry |
235 | for my $f (keys %$functions) { |
236 | next if $except{ $f }; |
237 | next unless $functions->{ $f } |
238 | and *{ $functions->{ $f } }{CODE}; |
239 | $store->{remove}{ $f } = 1; |
240 | } |
241 | |
242 | # register EOF handler on first call to import |
243 | unless ($store->{handler_is_installed}) { |
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244 | on_scope_end { |
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245 | $RemoveSubs->($cleanee, $store, keys %{ $store->{remove} }); |
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246 | }; |
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247 | $store->{handler_is_installed} = 1; |
248 | } |
249 | |
250 | return 1; |
251 | } |
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252 | } |
253 | |
254 | =head2 unimport |
255 | |
256 | This method will be called when you do a |
257 | |
258 | no namespace::clean; |
259 | |
260 | It will start a new section of code that defines functions to clean up. |
261 | |
262 | =cut |
263 | |
264 | sub unimport { |
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265 | my ($pragma, %args) = @_; |
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266 | |
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267 | # the calling class, the current functions and our storage |
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268 | my $cleanee = exists $args{ -cleanee } ? $args{ -cleanee } : scalar caller; |
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269 | my $functions = $pragma->get_functions($cleanee); |
270 | my $store = $pragma->get_class_store($cleanee); |
271 | |
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272 | # register all unknown previous functions as excluded |
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273 | for my $f (keys %$functions) { |
274 | next if $store->{remove}{ $f } |
275 | or $store->{exclude}{ $f }; |
276 | $store->{exclude}{ $f } = 1; |
277 | } |
278 | |
279 | return 1; |
280 | } |
281 | |
282 | =head2 get_class_store |
283 | |
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284 | This returns a reference to a hash in a passed package containing |
285 | information about function names included and excluded from removal. |
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286 | |
287 | =cut |
288 | |
289 | sub get_class_store { |
290 | my ($pragma, $class) = @_; |
291 | no strict 'refs'; |
292 | return \%{ "${class}::${STORAGE_VAR}" }; |
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293 | } |
294 | |
295 | =head2 get_functions |
296 | |
297 | Takes a class as argument and returns all currently defined functions |
298 | in it as a hash reference with the function name as key and a typeglob |
299 | reference to the symbol as value. |
300 | |
301 | =cut |
302 | |
303 | sub get_functions { |
304 | my ($pragma, $class) = @_; |
305 | |
306 | return { |
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307 | map { @$_ } # key => value |
308 | grep { *{ $_->[1] }{CODE} } # only functions |
309 | map { [$_, qualify_to_ref( $_, $class )] } # get globref |
310 | grep { $_ !~ /::$/ } # no packages |
311 | do { no strict 'refs'; keys %{ "${class}::" } } # symbol entries |
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312 | }; |
313 | } |
314 | |
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315 | =head1 IMPLEMENTATION DETAILS |
316 | |
317 | This module works through the effect that a |
318 | |
319 | delete $SomePackage::{foo}; |
320 | |
321 | will remove the C<foo> symbol from C<$SomePackage> for run time lookups |
322 | (e.g., method calls) but will leave the entry alive to be called by |
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323 | already resolved names in the package itself. C<namespace::clean> will |
324 | restore and therefor in effect keep all glob slots that aren't C<CODE>. |
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325 | |
326 | A test file has been added to the perl core to ensure that this behaviour |
327 | will be stable in future releases. |
328 | |
329 | Just for completeness sake, if you want to remove the symbol completely, |
330 | use C<undef> instead. |
331 | |
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332 | =head1 SEE ALSO |
333 | |
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334 | L<B::Hooks::EndOfScope> |
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335 | |
336 | =head1 AUTHOR AND COPYRIGHT |
337 | |
338 | Robert 'phaylon' Sedlacek C<E<lt>rs@474.atE<gt>>, with many thanks to |
339 | Matt S Trout for the inspiration on the whole idea. |
340 | |
341 | =head1 LICENSE |
342 | |
343 | This program is free software; you can redistribute it and/or modify |
344 | it under the same terms as perl itself. |
345 | |
346 | =cut |
347 | |
de673bbf |
348 | no warnings; |
349 | 'Danger! Laws of Thermodynamics may not apply.' |