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;
184 $RemoveSubs->($cleanee, $store, keys %{ $store->{remove} });
192 my ($pragma, %args) = @_;
194 # the calling class, the current functions and our storage
195 my $cleanee = exists $args{ -cleanee } ? $args{ -cleanee } : scalar caller;
196 my $functions = $pragma->get_functions($cleanee);
197 my $store = $pragma->get_class_store($cleanee);
199 # register all unknown previous functions as excluded
200 for my $f (keys %$functions) {
201 next if $store->{remove}{ $f }
202 or $store->{exclude}{ $f };
203 $store->{exclude}{ $f } = 1;
209 sub get_class_store {
210 my ($pragma, $class) = @_;
211 my $stash = stash_for($class);
212 my $var = "%$STORAGE_VAR";
213 $stash->add_symbol($var, {})
214 unless $stash->has_symbol($var);
215 return $stash->get_symbol($var);
219 my ($pragma, $class) = @_;
221 my $stash = stash_for($class);
223 map { $_ => $stash->get_symbol("&$_") }
224 $stash->list_all_symbols('CODE')
228 'Danger! Laws of Thermodynamics may not apply.'
234 namespace::clean - Keep imports and functions out of your namespace
242 use Carp qw(croak); # 'croak' will be removed
244 sub bar { 23 } # 'bar' will be removed
246 # remove all previously defined functions
247 use namespace::clean;
249 sub baz { bar() } # 'baz' still defined, 'bar' still bound
251 # begin to collection function names from here again
254 sub quux { baz() } # 'quux' will be removed
256 # remove all functions defined after the 'no' unimport
257 use namespace::clean;
259 # Will print: 'No', 'No', 'Yes' and 'No'
260 print +(__PACKAGE__->can('croak') ? 'Yes' : 'No'), "\n";
261 print +(__PACKAGE__->can('bar') ? 'Yes' : 'No'), "\n";
262 print +(__PACKAGE__->can('baz') ? 'Yes' : 'No'), "\n";
263 print +(__PACKAGE__->can('quux') ? 'Yes' : 'No'), "\n";
269 =head2 Keeping packages clean
271 When you define a function, or import one, into a Perl package, it will
272 naturally also be available as a method. This does not per se cause
273 problems, but it can complicate subclassing and, for example, plugin
274 classes that are included via multiple inheritance by loading them as
277 The C<namespace::clean> pragma will remove all previously declared or
278 imported symbols at the end of the current package's compile cycle.
279 Functions called in the package itself will still be bound by their
280 name, but they won't show up as methods on your class or instances.
282 By unimporting via C<no> you can tell C<namespace::clean> to start
283 collecting functions for the next C<use namespace::clean;> specification.
285 You can use the C<-except> flag to tell C<namespace::clean> that you
286 don't want it to remove a certain function or method. A common use would
287 be a module exporting an C<import> method along with some functions:
289 use ModuleExportingImport;
290 use namespace::clean -except => [qw( import )];
292 If you just want to C<-except> a single sub, you can pass it directly.
293 For more than one value you have to use an array reference.
295 =head3 Late binding caveat
297 Note that the L<technique used by this module|/IMPLEMENTATION DETAILS> relies
298 on perl having resolved all names to actual code references during the
299 compilation of a scope. While this is almost always what the interpreter does,
300 there are some exceptions, notably the L<sort SUBNAME|perlfunc/sort> style of
301 the C<sort> built-in invocation. The following example will not work, because
302 C<sort> does not try to resolve the function name to an actual code reference
305 use MyApp::Utils 'my_sorter';
306 use namespace::clean;
308 my @sorted = sort my_sorter @list;
310 You need to work around this by forcing a compile-time resolution like so:
312 use MyApp::Utils 'sorter';
313 use namespace::clean;
315 my $my_sorter_cref = \&sorter;
317 my @sorted = sort $my_sorter_cref @list;
319 =head2 Explicitly removing functions when your scope is compiled
321 It is also possible to explicitly tell C<namespace::clean> what packages
322 to remove when the surrounding scope has finished compiling. Here is an
328 # blessed NOT available
331 use Scalar::Util qw( blessed );
332 use namespace::clean qw( blessed );
335 return blessed shift;
338 # blessed NOT available
342 When using C<namespace::clean> together with L<Moose> you want to keep
343 the installed C<meta> method. So your classes should look like:
347 use namespace::clean -except => 'meta';
350 Same goes for L<Moose::Role>.
352 =head2 Cleaning other packages
354 You can tell C<namespace::clean> that you want to clean up another package
355 instead of the one importing. To do this you have to pass in the C<-cleanee>
358 package My::MooseX::namespace::clean;
361 use namespace::clean (); # no cleanup, just load
364 namespace::clean->import(
365 -cleanee => scalar(caller),
370 If you don't care about C<namespace::clean>s discover-and-C<-except> logic, and
371 just want to remove subroutines, try L</clean_subroutines>.
375 =head2 clean_subroutines
377 This exposes the actual subroutine-removal logic.
379 namespace::clean->clean_subroutines($cleanee, qw( subA subB ));
381 will remove C<subA> and C<subB> from C<$cleanee>. Note that this will remove the
382 subroutines B<immediately> and not wait for scope end. If you want to have this
383 effect at a specific time (e.g. C<namespace::clean> acts on scope compile end)
384 it is your responsibility to make sure it runs at that time.
388 Makes a snapshot of the current defined functions and installs a
389 L<B::Hooks::EndOfScope> hook in the current scope to invoke the cleanups.
394 This method will be called when you do a
398 It will start a new section of code that defines functions to clean up.
400 =head2 get_class_store
402 This returns a reference to a hash in a passed package containing
403 information about function names included and excluded from removal.
407 Takes a class as argument and returns all currently defined functions
408 in it as a hash reference with the function name as key and a typeglob
409 reference to the symbol as value.
411 =head1 IMPLEMENTATION DETAILS
413 This module works through the effect that a
415 delete $SomePackage::{foo};
417 will remove the C<foo> symbol from C<$SomePackage> for run time lookups
418 (e.g., method calls) but will leave the entry alive to be called by
419 already resolved names in the package itself. C<namespace::clean> will
420 restore and therefor in effect keep all glob slots that aren't C<CODE>.
422 A test file has been added to the perl core to ensure that this behaviour
423 will be stable in future releases.
425 Just for completeness sake, if you want to remove the symbol completely,
426 use C<undef> instead.
430 L<B::Hooks::EndOfScope>
434 Many thanks to Matt S Trout for the inspiration on the whole idea.
442 Robert 'phaylon' Sedlacek <rs@474.at>
446 Florian Ragwitz <rafl@debian.org>
450 Jesse Luehrs <doy@tozt.net>
454 Peter Rabbitson <ribasushi@cpan.org>
458 Father Chrysostomos <sprout@cpan.org>
462 =head1 COPYRIGHT AND LICENSE
464 This software is copyright (c) 2011 by L</AUTHORS>
466 This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.