1 package namespace::clean;
7 $VERSION = eval $VERSION if $VERSION =~ /_/; # numify for warning-free dev releases
9 our $STORAGE_VAR = '__NAMESPACE_CLEAN_STORAGE';
11 use B::Hooks::EndOfScope 'on_scope_end';
13 # FIXME This is a crock of shit, needs to go away
14 # currently here to work around https://rt.cpan.org/Ticket/Display.html?id=74151
15 # kill with fire when PS::XS is *finally* fixed
19 if ( $] < 5.008007 ) {
20 require Package::Stash::PP;
21 $provider = 'Package::Stash::PP';
24 require Package::Stash;
25 $provider = 'Package::Stash';
27 eval <<"EOS" or die $@;
30 $provider->new(\$_[0]);
38 use namespace::clean::_Util qw( DEBUGGER_NEEDS_CV_RENAME DEBUGGER_NEEDS_CV_PIVOT );
40 # Built-in debugger CV-retrieval fixups necessary before perl 5.15.5:
41 # since we are deleting the glob where the subroutine was originally
42 # defined, the assumptions below no longer hold.
44 # In 5.8.9 ~ 5.13.5 (inclusive) the debugger assumes that a CV can
45 # always be found under sub_fullname($sub)
46 # Workaround: use sub naming to properly name the sub hidden in the package's
49 # In the rest of the range ( ... ~ 5.8.8 and 5.13.6 ~ 5.15.4 ) the debugger
50 # assumes the name of the glob passed to entersub can be used to find the CV
51 # Workaround: realias the original glob to the deleted-stash slot
53 # Can not tie constants to the current value of $^P directly,
54 # as the debugger can be enabled during runtime (kinda dubious)
57 my $RemoveSubs = sub {
60 my $cleanee_stash = stash_for($cleanee);
66 # ignore already removed symbols
67 next SYMBOL if $store->{exclude}{ $f };
69 my $sub = $cleanee_stash->get_symbol("&$f")
72 my $need_debugger_fixup =
73 ( DEBUGGER_NEEDS_CV_RENAME or DEBUGGER_NEEDS_CV_PIVOT )
77 ref(my $globref = \$cleanee_stash->namespace->{$f}) eq 'GLOB'
79 ( $deleted_stash ||= stash_for("namespace::clean::deleted::$cleanee") )
82 # convince the Perl debugger to work
83 # see the comment on top
84 if ( DEBUGGER_NEEDS_CV_RENAME and $need_debugger_fixup ) {
86 # Note - both get_subname and set_subname are only compiled when CV_RENAME
87 # is true ( the 5.8.9 ~ 5.12 range ). On other perls this entire block is
88 # constant folded away, and so are the definitions in ::_Util
90 # Do not be surprised that they are missing without DEBUGGER_NEEDS_CV_RENAME
92 namespace::clean::_Util::get_subname( $sub ) eq ( $cleanee_stash->name . "::$f" )
94 $deleted_stash->add_symbol(
96 namespace::clean::_Util::set_subname( $deleted_stash->name . "::$f", $sub ),
99 elsif ( DEBUGGER_NEEDS_CV_PIVOT and $need_debugger_fixup ) {
100 $deleted_stash->add_symbol("&$f", $sub);
105 my $def = $cleanee_stash->get_symbol($name);
106 defined($def) ? [$name, $def] : ()
109 $cleanee_stash->remove_glob($f);
111 # if this perl needs no renaming trick we need to
112 # rename the original glob after the fact
113 DEBUGGER_NEEDS_CV_PIVOT
117 *$globref = $deleted_stash->namespace->{$f};
119 $cleanee_stash->add_symbol(@$_) for @symbols;
123 sub clean_subroutines {
124 my ($nc, $cleanee, @subs) = @_;
125 $RemoveSubs->($cleanee, {}, @subs);
129 my ($pragma, @args) = @_;
131 my (%args, $is_explicit);
136 if ($args[0] =~ /^\-/) {
137 my $key = shift @args;
138 my $value = shift @args;
139 $args{ $key } = $value;
147 my $cleanee = exists $args{ -cleanee } ? $args{ -cleanee } : scalar caller;
150 $RemoveSubs->($cleanee, {}, @args);
155 # calling class, all current functions and our storage
156 my $functions = $pragma->get_functions($cleanee);
157 my $store = $pragma->get_class_store($cleanee);
158 my $stash = stash_for($cleanee);
160 # except parameter can be array ref or single value
161 my %except = map {( $_ => 1 )} (
163 ? ( ref $args{ -except } eq 'ARRAY' ? @{ $args{ -except } } : $args{ -except } )
167 # register symbols for removal, if they have a CODE entry
168 for my $f (keys %$functions) {
169 next if $except{ $f };
170 next unless $stash->has_symbol("&$f");
171 $store->{remove}{ $f } = 1;
174 # register EOF handler on first call to import
175 unless ($store->{handler_is_installed}) {
177 $RemoveSubs->($cleanee, $store, keys %{ $store->{remove} });
179 $store->{handler_is_installed} = 1;
187 my ($pragma, %args) = @_;
189 # the calling class, the current functions and our storage
190 my $cleanee = exists $args{ -cleanee } ? $args{ -cleanee } : scalar caller;
191 my $functions = $pragma->get_functions($cleanee);
192 my $store = $pragma->get_class_store($cleanee);
194 # register all unknown previous functions as excluded
195 for my $f (keys %$functions) {
196 next if $store->{remove}{ $f }
197 or $store->{exclude}{ $f };
198 $store->{exclude}{ $f } = 1;
204 sub get_class_store {
205 my ($pragma, $class) = @_;
206 my $stash = stash_for($class);
207 my $var = "%$STORAGE_VAR";
208 $stash->add_symbol($var, {})
209 unless $stash->has_symbol($var);
210 return $stash->get_symbol($var);
214 my ($pragma, $class) = @_;
216 my $stash = stash_for($class);
218 map { $_ => $stash->get_symbol("&$_") }
219 $stash->list_all_symbols('CODE')
223 'Danger! Laws of Thermodynamics may not apply.'
229 namespace::clean - Keep imports and functions out of your namespace
237 use Carp qw(croak); # 'croak' will be removed
239 sub bar { 23 } # 'bar' will be removed
241 # remove all previously defined functions
242 use namespace::clean;
244 sub baz { bar() } # 'baz' still defined, 'bar' still bound
246 # begin to collection function names from here again
249 sub quux { baz() } # 'quux' will be removed
251 # remove all functions defined after the 'no' unimport
252 use namespace::clean;
254 # Will print: 'No', 'No', 'Yes' and 'No'
255 print +(__PACKAGE__->can('croak') ? 'Yes' : 'No'), "\n";
256 print +(__PACKAGE__->can('bar') ? 'Yes' : 'No'), "\n";
257 print +(__PACKAGE__->can('baz') ? 'Yes' : 'No'), "\n";
258 print +(__PACKAGE__->can('quux') ? 'Yes' : 'No'), "\n";
264 =head2 Keeping packages clean
266 When you define a function, or import one, into a Perl package, it will
267 naturally also be available as a method. This does not per se cause
268 problems, but it can complicate subclassing and, for example, plugin
269 classes that are included via multiple inheritance by loading them as
272 The C<namespace::clean> pragma will remove all previously declared or
273 imported symbols at the end of the current package's compile cycle.
274 Functions called in the package itself will still be bound by their
275 name, but they won't show up as methods on your class or instances.
277 By unimporting via C<no> you can tell C<namespace::clean> to start
278 collecting functions for the next C<use namespace::clean;> specification.
280 You can use the C<-except> flag to tell C<namespace::clean> that you
281 don't want it to remove a certain function or method. A common use would
282 be a module exporting an C<import> method along with some functions:
284 use ModuleExportingImport;
285 use namespace::clean -except => [qw( import )];
287 If you just want to C<-except> a single sub, you can pass it directly.
288 For more than one value you have to use an array reference.
290 =head3 Late binding caveat
292 Note that the L<technique used by this module|/IMPLEMENTATION DETAILS> relies
293 on perl having resolved all names to actual code references during the
294 compilation of a scope. While this is almost always what the interpreter does,
295 there are some exceptions, notably the L<sort SUBNAME|perlfunc/sort> style of
296 the C<sort> built-in invocation. The following example will not work, because
297 C<sort> does not try to resolve the function name to an actual code reference
300 use MyApp::Utils 'my_sorter';
301 use namespace::clean;
303 my @sorted = sort my_sorter @list;
305 You need to work around this by forcing a compile-time resolution like so:
307 use MyApp::Utils 'sorter';
308 use namespace::clean;
310 my $my_sorter_cref = \&sorter;
312 my @sorted = sort $my_sorter_cref @list;
314 =head2 Explicitly removing functions when your scope is compiled
316 It is also possible to explicitly tell C<namespace::clean> what packages
317 to remove when the surrounding scope has finished compiling. Here is an
323 # blessed NOT available
326 use Scalar::Util qw( blessed );
327 use namespace::clean qw( blessed );
330 return blessed shift;
333 # blessed NOT available
337 When using C<namespace::clean> together with L<Moose> you want to keep
338 the installed C<meta> method. So your classes should look like:
342 use namespace::clean -except => 'meta';
345 Same goes for L<Moose::Role>.
347 =head2 Cleaning other packages
349 You can tell C<namespace::clean> that you want to clean up another package
350 instead of the one importing. To do this you have to pass in the C<-cleanee>
353 package My::MooseX::namespace::clean;
356 use namespace::clean (); # no cleanup, just load
359 namespace::clean->import(
360 -cleanee => scalar(caller),
365 If you don't care about C<namespace::clean>s discover-and-C<-except> logic, and
366 just want to remove subroutines, try L</clean_subroutines>.
370 =head2 clean_subroutines
372 This exposes the actual subroutine-removal logic.
374 namespace::clean->clean_subroutines($cleanee, qw( subA subB ));
376 will remove C<subA> and C<subB> from C<$cleanee>. Note that this will remove the
377 subroutines B<immediately> and not wait for scope end. If you want to have this
378 effect at a specific time (e.g. C<namespace::clean> acts on scope compile end)
379 it is your responsibility to make sure it runs at that time.
383 Makes a snapshot of the current defined functions and installs a
384 L<B::Hooks::EndOfScope> hook in the current scope to invoke the cleanups.
389 This method will be called when you do a
393 It will start a new section of code that defines functions to clean up.
395 =head2 get_class_store
397 This returns a reference to a hash in a passed package containing
398 information about function names included and excluded from removal.
402 Takes a class as argument and returns all currently defined functions
403 in it as a hash reference with the function name as key and a typeglob
404 reference to the symbol as value.
406 =head1 IMPLEMENTATION DETAILS
408 This module works through the effect that a
410 delete $SomePackage::{foo};
412 will remove the C<foo> symbol from C<$SomePackage> for run time lookups
413 (e.g., method calls) but will leave the entry alive to be called by
414 already resolved names in the package itself. C<namespace::clean> will
415 restore and therefor in effect keep all glob slots that aren't C<CODE>.
417 A test file has been added to the perl core to ensure that this behaviour
418 will be stable in future releases.
420 Just for completeness sake, if you want to remove the symbol completely,
421 use C<undef> instead.
425 L<B::Hooks::EndOfScope>
429 Many thanks to Matt S Trout for the inspiration on the whole idea.
437 Robert 'phaylon' Sedlacek <rs@474.at>
441 Florian Ragwitz <rafl@debian.org>
445 Jesse Luehrs <doy@tozt.net>
449 Peter Rabbitson <ribasushi@cpan.org>
453 Father Chrysostomos <sprout@cpan.org>
457 =head1 COPYRIGHT AND LICENSE
459 This software is copyright (c) 2011 by L</AUTHORS>
461 This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.