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1 | package namespace::clean; |
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2 | # ABSTRACT: Keep imports and functions out of your namespace |
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3 | |
4 | use warnings; |
5 | use strict; |
6 | |
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7 | use vars qw( $STORAGE_VAR ); |
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8 | use Package::Stash 0.22; |
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9 | use B::Hooks::EndOfScope 0.07; |
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10 | |
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11 | $STORAGE_VAR = '__NAMESPACE_CLEAN_STORAGE'; |
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12 | |
13 | =head1 SYNOPSIS |
14 | |
15 | package Foo; |
16 | use warnings; |
17 | use strict; |
18 | |
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19 | use Carp qw(croak); # 'croak' will be removed |
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20 | |
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21 | sub bar { 23 } # 'bar' will be removed |
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22 | |
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23 | # remove all previously defined functions |
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24 | use namespace::clean; |
25 | |
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26 | sub baz { bar() } # 'baz' still defined, 'bar' still bound |
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27 | |
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28 | # begin to collection function names from here again |
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29 | no namespace::clean; |
30 | |
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31 | sub quux { baz() } # 'quux' will be removed |
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32 | |
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33 | # remove all functions defined after the 'no' unimport |
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34 | use namespace::clean; |
35 | |
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36 | # Will print: 'No', 'No', 'Yes' and 'No' |
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37 | print +(__PACKAGE__->can('croak') ? 'Yes' : 'No'), "\n"; |
38 | print +(__PACKAGE__->can('bar') ? 'Yes' : 'No'), "\n"; |
39 | print +(__PACKAGE__->can('baz') ? 'Yes' : 'No'), "\n"; |
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40 | print +(__PACKAGE__->can('quux') ? 'Yes' : 'No'), "\n"; |
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41 | |
42 | 1; |
43 | |
44 | =head1 DESCRIPTION |
45 | |
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46 | =head2 Keeping packages clean |
47 | |
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48 | When you define a function, or import one, into a Perl package, it will |
49 | naturally also be available as a method. This does not per se cause |
50 | problems, but it can complicate subclassing and, for example, plugin |
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51 | classes that are included via multiple inheritance by loading them as |
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52 | base classes. |
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53 | |
54 | The C<namespace::clean> pragma will remove all previously declared or |
55 | imported symbols at the end of the current package's compile cycle. |
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56 | Functions called in the package itself will still be bound by their |
57 | name, but they won't show up as methods on your class or instances. |
58 | |
59 | By unimporting via C<no> you can tell C<namespace::clean> to start |
60 | collecting functions for the next C<use namespace::clean;> specification. |
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61 | |
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62 | You can use the C<-except> flag to tell C<namespace::clean> that you |
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63 | don't want it to remove a certain function or method. A common use would |
64 | be a module exporting an C<import> method along with some functions: |
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65 | |
66 | use ModuleExportingImport; |
67 | use namespace::clean -except => [qw( import )]; |
68 | |
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69 | If you just want to C<-except> a single sub, you can pass it directly. |
70 | For more than one value you have to use an array reference. |
71 | |
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72 | =head2 Explicitely removing functions when your scope is compiled |
73 | |
74 | It is also possible to explicitely tell C<namespace::clean> what packages |
75 | to remove when the surrounding scope has finished compiling. Here is an |
76 | example: |
77 | |
78 | package Foo; |
79 | use strict; |
80 | |
81 | # blessed NOT available |
82 | |
83 | sub my_class { |
84 | use Scalar::Util qw( blessed ); |
85 | use namespace::clean qw( blessed ); |
86 | |
87 | # blessed available |
88 | return blessed shift; |
89 | } |
90 | |
91 | # blessed NOT available |
92 | |
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93 | =head2 Moose |
94 | |
95 | When using C<namespace::clean> together with L<Moose> you want to keep |
96 | the installed C<meta> method. So your classes should look like: |
97 | |
98 | package Foo; |
99 | use Moose; |
100 | use namespace::clean -except => 'meta'; |
101 | ... |
102 | |
103 | Same goes for L<Moose::Role>. |
104 | |
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105 | =head2 Cleaning other packages |
106 | |
107 | You can tell C<namespace::clean> that you want to clean up another package |
108 | instead of the one importing. To do this you have to pass in the C<-cleanee> |
109 | option like this: |
110 | |
111 | package My::MooseX::namespace::clean; |
112 | use strict; |
113 | |
114 | use namespace::clean (); # no cleanup, just load |
115 | |
116 | sub import { |
117 | namespace::clean->import( |
118 | -cleanee => scalar(caller), |
119 | -except => 'meta', |
120 | ); |
121 | } |
122 | |
123 | If you don't care about C<namespace::clean>s discover-and-C<-except> logic, and |
124 | just want to remove subroutines, try L</clean_subroutines>. |
125 | |
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126 | =method clean_subroutines |
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127 | |
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128 | This exposes the actual subroutine-removal logic. |
129 | |
130 | namespace::clean->clean_subroutines($cleanee, qw( subA subB )); |
131 | |
132 | will remove C<subA> and C<subB> from C<$cleanee>. Note that this will remove the |
133 | subroutines B<immediately> and not wait for scope end. If you want to have this |
134 | effect at a specific time (e.g. C<namespace::clean> acts on scope compile end) |
135 | it is your responsibility to make sure it runs at that time. |
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136 | |
137 | =cut |
138 | |
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139 | my $sub_utils_loaded; |
140 | my $DebuggerRename = sub { |
141 | my ($f, $sub, $cleanee_stash, $deleted_stash) = @_; |
142 | |
143 | if (! defined $sub_utils_loaded ) { |
144 | $sub_utils_loaded = do { |
145 | my $sn_ver = 0.04; |
146 | eval { require Sub::Name; Sub::Name->VERSION($sn_ver) } |
147 | or die "Sub::Name $sn_ver required when running under -d or equivalent: $@"; |
148 | |
149 | my $si_ver = 0.04; |
150 | eval { require Sub::Identify; Sub::Identify->VERSION($si_ver) } |
151 | or die "Sub::Identify $si_ver required when running under -d or equivalent: $@"; |
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152 | |
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153 | 1; |
154 | } ? 1 : 0; |
155 | } |
156 | |
157 | if ( Sub::Identify::sub_fullname($sub) eq ($cleanee_stash->name . "::$f") ) { |
158 | my $new_fq = $deleted_stash->name . "::$f"; |
159 | Sub::Name::subname($new_fq, $sub); |
160 | $deleted_stash->add_symbol("&$f", $sub); |
161 | } |
162 | }; |
163 | |
164 | my $RemoveSubs = sub { |
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165 | my $cleanee = shift; |
166 | my $store = shift; |
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167 | my $cleanee_stash = Package::Stash->new($cleanee); |
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168 | my $deleted_stash; |
169 | |
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170 | SYMBOL: |
171 | for my $f (@_) { |
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172 | |
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173 | # ignore already removed symbols |
174 | next SYMBOL if $store->{exclude}{ $f }; |
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175 | |
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176 | my $sub = $cleanee_stash->get_symbol("&$f") |
177 | or next SYMBOL; |
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178 | |
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179 | if ($^P and ref(\$cleanee_stash->namespace->{$f}) eq 'GLOB') { |
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180 | # convince the Perl debugger to work |
181 | # it assumes that sub_fullname($sub) can always be used to find the CV again |
182 | # since we are deleting the glob where the subroutine was originally |
183 | # defined, that assumption no longer holds, so we need to move it |
184 | # elsewhere and point the CV's name to the new glob. |
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185 | $DebuggerRename->( |
186 | $f, |
187 | $sub, |
188 | $cleanee_stash, |
189 | $deleted_stash ||= Package::Stash->new("namespace::clean::deleted::$cleanee"), |
190 | ); |
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191 | } |
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192 | |
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193 | my @symbols = map { |
194 | my $name = $_ . $f; |
195 | my $def = $cleanee_stash->get_symbol($name); |
196 | defined($def) ? [$name, $def] : () |
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197 | } '$', '@', '%', ''; |
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198 | |
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199 | $cleanee_stash->remove_glob($f); |
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200 | |
201 | $cleanee_stash->add_symbol(@$_) for @symbols; |
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202 | } |
203 | }; |
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204 | |
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205 | sub clean_subroutines { |
206 | my ($nc, $cleanee, @subs) = @_; |
207 | $RemoveSubs->($cleanee, {}, @subs); |
208 | } |
209 | |
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210 | =method import |
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211 | |
212 | Makes a snapshot of the current defined functions and installs a |
213 | L<B::Hooks::EndOfScope> hook in the current scope to invoke the cleanups. |
214 | |
215 | =cut |
216 | |
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217 | sub import { |
218 | my ($pragma, @args) = @_; |
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219 | |
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220 | my (%args, $is_explicit); |
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221 | |
222 | ARG: |
223 | while (@args) { |
224 | |
225 | if ($args[0] =~ /^\-/) { |
226 | my $key = shift @args; |
227 | my $value = shift @args; |
228 | $args{ $key } = $value; |
229 | } |
230 | else { |
231 | $is_explicit++; |
232 | last ARG; |
233 | } |
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234 | } |
235 | |
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236 | my $cleanee = exists $args{ -cleanee } ? $args{ -cleanee } : scalar caller; |
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237 | if ($is_explicit) { |
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238 | on_scope_end { |
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239 | $RemoveSubs->($cleanee, {}, @args); |
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240 | }; |
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241 | } |
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242 | else { |
243 | |
244 | # calling class, all current functions and our storage |
245 | my $functions = $pragma->get_functions($cleanee); |
246 | my $store = $pragma->get_class_store($cleanee); |
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247 | my $stash = Package::Stash->new($cleanee); |
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248 | |
249 | # except parameter can be array ref or single value |
250 | my %except = map {( $_ => 1 )} ( |
251 | $args{ -except } |
252 | ? ( ref $args{ -except } eq 'ARRAY' ? @{ $args{ -except } } : $args{ -except } ) |
253 | : () |
254 | ); |
255 | |
256 | # register symbols for removal, if they have a CODE entry |
257 | for my $f (keys %$functions) { |
258 | next if $except{ $f }; |
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259 | next unless $stash->has_symbol("&$f"); |
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260 | $store->{remove}{ $f } = 1; |
261 | } |
262 | |
263 | # register EOF handler on first call to import |
264 | unless ($store->{handler_is_installed}) { |
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265 | on_scope_end { |
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266 | $RemoveSubs->($cleanee, $store, keys %{ $store->{remove} }); |
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267 | }; |
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268 | $store->{handler_is_installed} = 1; |
269 | } |
270 | |
271 | return 1; |
272 | } |
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273 | } |
274 | |
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275 | =method unimport |
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276 | |
277 | This method will be called when you do a |
278 | |
279 | no namespace::clean; |
280 | |
281 | It will start a new section of code that defines functions to clean up. |
282 | |
283 | =cut |
284 | |
285 | sub unimport { |
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286 | my ($pragma, %args) = @_; |
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287 | |
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288 | # the calling class, the current functions and our storage |
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289 | my $cleanee = exists $args{ -cleanee } ? $args{ -cleanee } : scalar caller; |
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290 | my $functions = $pragma->get_functions($cleanee); |
291 | my $store = $pragma->get_class_store($cleanee); |
292 | |
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293 | # register all unknown previous functions as excluded |
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294 | for my $f (keys %$functions) { |
295 | next if $store->{remove}{ $f } |
296 | or $store->{exclude}{ $f }; |
297 | $store->{exclude}{ $f } = 1; |
298 | } |
299 | |
300 | return 1; |
301 | } |
302 | |
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303 | =method get_class_store |
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304 | |
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305 | This returns a reference to a hash in a passed package containing |
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306 | information about function names included and excluded from removal. |
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307 | |
308 | =cut |
309 | |
310 | sub get_class_store { |
311 | my ($pragma, $class) = @_; |
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312 | my $stash = Package::Stash->new($class); |
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313 | my $var = "%$STORAGE_VAR"; |
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314 | $stash->add_symbol($var, {}) |
315 | unless $stash->has_symbol($var); |
316 | return $stash->get_symbol($var); |
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317 | } |
318 | |
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319 | =method get_functions |
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320 | |
321 | Takes a class as argument and returns all currently defined functions |
322 | in it as a hash reference with the function name as key and a typeglob |
323 | reference to the symbol as value. |
324 | |
325 | =cut |
326 | |
327 | sub get_functions { |
328 | my ($pragma, $class) = @_; |
329 | |
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330 | my $stash = Package::Stash->new($class); |
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331 | return { |
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332 | map { $_ => $stash->get_symbol("&$_") } |
333 | $stash->list_all_symbols('CODE') |
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334 | }; |
335 | } |
336 | |
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337 | =head1 IMPLEMENTATION DETAILS |
338 | |
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339 | This module works through the effect that a |
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340 | |
341 | delete $SomePackage::{foo}; |
342 | |
343 | will remove the C<foo> symbol from C<$SomePackage> for run time lookups |
344 | (e.g., method calls) but will leave the entry alive to be called by |
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345 | already resolved names in the package itself. C<namespace::clean> will |
346 | restore and therefor in effect keep all glob slots that aren't C<CODE>. |
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347 | |
348 | A test file has been added to the perl core to ensure that this behaviour |
349 | will be stable in future releases. |
350 | |
351 | Just for completeness sake, if you want to remove the symbol completely, |
352 | use C<undef> instead. |
353 | |
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354 | =head1 SEE ALSO |
355 | |
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356 | L<B::Hooks::EndOfScope> |
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357 | |
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358 | =head1 THANKS |
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359 | |
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360 | Many thanks to Matt S Trout for the inspiration on the whole idea. |
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361 | |
362 | =cut |
363 | |
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364 | no warnings; |
365 | 'Danger! Laws of Thermodynamics may not apply.' |