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 # While the errors manifest themselves inside perl5db.pl, they are caused by
54 # problems inside the interpreter. If enabled ($^P & 0x01) and existent,
55 # the DB::sub sub will be called by the interpreter for any sub call rather
56 # that call the sub directly. It is provided the real sub to call in $DB::sub,
57 # but the value given has the issues described above. We only have to enable
58 # the workaround if DB::sub will be used.
60 # Can not tie constants to the current value of $^P directly,
61 # as the debugger can be enabled during runtime (kinda dubious)
64 my $RemoveSubs = sub {
67 my $cleanee_stash = stash_for($cleanee);
73 # ignore already removed symbols
74 next SYMBOL if $store->{exclude}{ $f };
76 my $sub = $cleanee_stash->get_symbol("&$f")
79 my $need_debugger_fixup =
80 ( DEBUGGER_NEEDS_CV_RENAME or DEBUGGER_NEEDS_CV_PIVOT )
86 ref(my $globref = \$cleanee_stash->namespace->{$f}) eq 'GLOB'
88 ( $deleted_stash ||= stash_for("namespace::clean::deleted::$cleanee") )
91 # convince the Perl debugger to work
92 # see the comment on top
93 if ( DEBUGGER_NEEDS_CV_RENAME and $need_debugger_fixup ) {
95 # Note - both get_subname and set_subname are only compiled when CV_RENAME
96 # is true ( the 5.8.9 ~ 5.12 range ). On other perls this entire block is
97 # constant folded away, and so are the definitions in ::_Util
99 # Do not be surprised that they are missing without DEBUGGER_NEEDS_CV_RENAME
101 namespace::clean::_Util::get_subname( $sub ) eq ( $cleanee_stash->name . "::$f" )
103 $deleted_stash->add_symbol(
105 namespace::clean::_Util::set_subname( $deleted_stash->name . "::$f", $sub ),
108 elsif ( DEBUGGER_NEEDS_CV_PIVOT and $need_debugger_fixup ) {
109 $deleted_stash->add_symbol("&$f", $sub);
114 my $def = $cleanee_stash->get_symbol($name);
115 defined($def) ? [$name, $def] : ()
118 $cleanee_stash->remove_glob($f);
120 # if this perl needs no renaming trick we need to
121 # rename the original glob after the fact
122 DEBUGGER_NEEDS_CV_PIVOT
126 *$globref = $deleted_stash->namespace->{$f};
128 $cleanee_stash->add_symbol(@$_) for @symbols;
132 sub clean_subroutines {
133 my ($nc, $cleanee, @subs) = @_;
134 $RemoveSubs->($cleanee, {}, @subs);
138 my ($pragma, @args) = @_;
140 my (%args, $is_explicit);
145 if ($args[0] =~ /^\-/) {
146 my $key = shift @args;
147 my $value = shift @args;
148 $args{ $key } = $value;
156 my $cleanee = exists $args{ -cleanee } ? $args{ -cleanee } : scalar caller;
159 $RemoveSubs->($cleanee, {}, @args);
164 # calling class, all current functions and our storage
165 my $functions = $pragma->get_functions($cleanee);
166 my $store = $pragma->get_class_store($cleanee);
167 my $stash = stash_for($cleanee);
169 # except parameter can be array ref or single value
170 my %except = map {( $_ => 1 )} (
172 ? ( ref $args{ -except } eq 'ARRAY' ? @{ $args{ -except } } : $args{ -except } )
176 # register symbols for removal, if they have a CODE entry
177 for my $f (keys %$functions) {
178 next if $except{ $f };
179 next unless $stash->has_symbol("&$f");
180 $store->{remove}{ $f } = 1;
183 # register EOF handler on first call to import
184 unless ($store->{handler_is_installed}) {
186 $RemoveSubs->($cleanee, $store, keys %{ $store->{remove} });
188 $store->{handler_is_installed} = 1;
196 my ($pragma, %args) = @_;
198 # the calling class, the current functions and our storage
199 my $cleanee = exists $args{ -cleanee } ? $args{ -cleanee } : scalar caller;
200 my $functions = $pragma->get_functions($cleanee);
201 my $store = $pragma->get_class_store($cleanee);
203 # register all unknown previous functions as excluded
204 for my $f (keys %$functions) {
205 next if $store->{remove}{ $f }
206 or $store->{exclude}{ $f };
207 $store->{exclude}{ $f } = 1;
213 sub get_class_store {
214 my ($pragma, $class) = @_;
215 my $stash = stash_for($class);
216 my $var = "%$STORAGE_VAR";
217 $stash->add_symbol($var, {})
218 unless $stash->has_symbol($var);
219 return $stash->get_symbol($var);
223 my ($pragma, $class) = @_;
225 my $stash = stash_for($class);
227 map { $_ => $stash->get_symbol("&$_") }
228 $stash->list_all_symbols('CODE')
232 'Danger! Laws of Thermodynamics may not apply.'
238 namespace::clean - Keep imports and functions out of your namespace
246 use Carp qw(croak); # 'croak' will be removed
248 sub bar { 23 } # 'bar' will be removed
250 # remove all previously defined functions
251 use namespace::clean;
253 sub baz { bar() } # 'baz' still defined, 'bar' still bound
255 # begin to collection function names from here again
258 sub quux { baz() } # 'quux' will be removed
260 # remove all functions defined after the 'no' unimport
261 use namespace::clean;
263 # Will print: 'No', 'No', 'Yes' and 'No'
264 print +(__PACKAGE__->can('croak') ? 'Yes' : 'No'), "\n";
265 print +(__PACKAGE__->can('bar') ? 'Yes' : 'No'), "\n";
266 print +(__PACKAGE__->can('baz') ? 'Yes' : 'No'), "\n";
267 print +(__PACKAGE__->can('quux') ? 'Yes' : 'No'), "\n";
273 =head2 Keeping packages clean
275 When you define a function, or import one, into a Perl package, it will
276 naturally also be available as a method. This does not per se cause
277 problems, but it can complicate subclassing and, for example, plugin
278 classes that are included via multiple inheritance by loading them as
281 The C<namespace::clean> pragma will remove all previously declared or
282 imported symbols at the end of the current package's compile cycle.
283 Functions called in the package itself will still be bound by their
284 name, but they won't show up as methods on your class or instances.
286 By unimporting via C<no> you can tell C<namespace::clean> to start
287 collecting functions for the next C<use namespace::clean;> specification.
289 You can use the C<-except> flag to tell C<namespace::clean> that you
290 don't want it to remove a certain function or method. A common use would
291 be a module exporting an C<import> method along with some functions:
293 use ModuleExportingImport;
294 use namespace::clean -except => [qw( import )];
296 If you just want to C<-except> a single sub, you can pass it directly.
297 For more than one value you have to use an array reference.
299 =head3 Late binding caveat
301 Note that the L<technique used by this module|/IMPLEMENTATION DETAILS> relies
302 on perl having resolved all names to actual code references during the
303 compilation of a scope. While this is almost always what the interpreter does,
304 there are some exceptions, notably the L<sort SUBNAME|perlfunc/sort> style of
305 the C<sort> built-in invocation. The following example will not work, because
306 C<sort> does not try to resolve the function name to an actual code reference
309 use MyApp::Utils 'my_sorter';
310 use namespace::clean;
312 my @sorted = sort my_sorter @list;
314 You need to work around this by forcing a compile-time resolution like so:
316 use MyApp::Utils 'sorter';
317 use namespace::clean;
319 my $my_sorter_cref = \&sorter;
321 my @sorted = sort $my_sorter_cref @list;
323 =head2 Explicitly removing functions when your scope is compiled
325 It is also possible to explicitly tell C<namespace::clean> what packages
326 to remove when the surrounding scope has finished compiling. Here is an
332 # blessed NOT available
335 use Scalar::Util qw( blessed );
336 use namespace::clean qw( blessed );
339 return blessed shift;
342 # blessed NOT available
346 When using C<namespace::clean> together with L<Moose> you want to keep
347 the installed C<meta> method. So your classes should look like:
351 use namespace::clean -except => 'meta';
354 Same goes for L<Moose::Role>.
356 =head2 Cleaning other packages
358 You can tell C<namespace::clean> that you want to clean up another package
359 instead of the one importing. To do this you have to pass in the C<-cleanee>
362 package My::MooseX::namespace::clean;
365 use namespace::clean (); # no cleanup, just load
368 namespace::clean->import(
369 -cleanee => scalar(caller),
374 If you don't care about C<namespace::clean>s discover-and-C<-except> logic, and
375 just want to remove subroutines, try L</clean_subroutines>.
379 =head2 clean_subroutines
381 This exposes the actual subroutine-removal logic.
383 namespace::clean->clean_subroutines($cleanee, qw( subA subB ));
385 will remove C<subA> and C<subB> from C<$cleanee>. Note that this will remove the
386 subroutines B<immediately> and not wait for scope end. If you want to have this
387 effect at a specific time (e.g. C<namespace::clean> acts on scope compile end)
388 it is your responsibility to make sure it runs at that time.
392 Makes a snapshot of the current defined functions and installs a
393 L<B::Hooks::EndOfScope> hook in the current scope to invoke the cleanups.
398 This method will be called when you do a
402 It will start a new section of code that defines functions to clean up.
404 =head2 get_class_store
406 This returns a reference to a hash in a passed package containing
407 information about function names included and excluded from removal.
411 Takes a class as argument and returns all currently defined functions
412 in it as a hash reference with the function name as key and a typeglob
413 reference to the symbol as value.
415 =head1 IMPLEMENTATION DETAILS
417 This module works through the effect that a
419 delete $SomePackage::{foo};
421 will remove the C<foo> symbol from C<$SomePackage> for run time lookups
422 (e.g., method calls) but will leave the entry alive to be called by
423 already resolved names in the package itself. C<namespace::clean> will
424 restore and therefor in effect keep all glob slots that aren't C<CODE>.
426 A test file has been added to the perl core to ensure that this behaviour
427 will be stable in future releases.
429 Just for completeness sake, if you want to remove the symbol completely,
430 use C<undef> instead.
434 L<B::Hooks::EndOfScope>
438 Many thanks to Matt S Trout for the inspiration on the whole idea.
446 Robert 'phaylon' Sedlacek <rs@474.at>
450 Florian Ragwitz <rafl@debian.org>
454 Jesse Luehrs <doy@tozt.net>
458 Peter Rabbitson <ribasushi@cpan.org>
462 Father Chrysostomos <sprout@cpan.org>
466 =head1 COPYRIGHT AND LICENSE
468 This software is copyright (c) 2011 by L</AUTHORS>
470 This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.