1 package namespace::clean;
2 # ABSTRACT: Keep imports and functions out of your namespace
7 use vars qw( $STORAGE_VAR );
10 our $VERSION = '0.21_01';
12 $STORAGE_VAR = '__NAMESPACE_CLEAN_STORAGE';
19 # when changing also change in Makefile.PL
20 my $b_h_eos_req = '0.07';
22 if (! $ENV{NAMESPACE_CLEAN_USE_PP} and eval {
23 require B::Hooks::EndOfScope;
24 B::Hooks::EndOfScope->VERSION($b_h_eos_req);
27 B::Hooks::EndOfScope->import('on_scope_end');
30 eval <<'PP' or die $@;
35 package namespace::clean::_TieHintHash;
40 use base 'Tie::ExtraHash';
44 package namespace::clean::_ScopeGuard;
49 sub arm { bless [ $_[1] ] }
51 sub DESTROY { $_[0]->[0]->() }
55 sub on_scope_end (&) {
58 if( my $stack = tied( %^H ) ) {
59 if ( (my $c = ref $stack) ne 'namespace::clean::_TieHintHash') {
61 ========================================================================
62 !!! F A T A L E R R O R !!!
64 foreign tie() of %^H detected
65 ========================================================================
67 namespace::clean is currently operating in pure-perl fallback mode, because
68 your system is lacking the necessary dependency B::Hooks::EndOfScope $b_h_eos_req.
69 In this mode namespace::clean expects to be able to tie() the hinthash %^H,
70 however it is apparently already tied by means unknown to the tie-class
73 Since this is a no-win situation execution will abort here and now. Please
74 try to find out which other module is relying on hinthash tie() ability,
75 and file a bug for both the perpetrator and namespace::clean, so that the
76 authors can figure out an acceptable way of moving forward.
80 push @$stack, namespace::clean::_ScopeGuard->arm(shift);
83 my %old_contents = %^H;
85 tie( %^H, 'namespace::clean::_TieHintHash', namespace::clean::_ScopeGuard->arm(shift) );
86 $^H{$_} = $old_contents{$_} for keys %old_contents;
99 namespace::clean - Keep imports and functions out of your namespace
107 use Carp qw(croak); # 'croak' will be removed
109 sub bar { 23 } # 'bar' will be removed
111 # remove all previously defined functions
112 use namespace::clean;
114 sub baz { bar() } # 'baz' still defined, 'bar' still bound
116 # begin to collection function names from here again
119 sub quux { baz() } # 'quux' will be removed
121 # remove all functions defined after the 'no' unimport
122 use namespace::clean;
124 # Will print: 'No', 'No', 'Yes' and 'No'
125 print +(__PACKAGE__->can('croak') ? 'Yes' : 'No'), "\n";
126 print +(__PACKAGE__->can('bar') ? 'Yes' : 'No'), "\n";
127 print +(__PACKAGE__->can('baz') ? 'Yes' : 'No'), "\n";
128 print +(__PACKAGE__->can('quux') ? 'Yes' : 'No'), "\n";
134 =head2 Keeping packages clean
136 When you define a function, or import one, into a Perl package, it will
137 naturally also be available as a method. This does not per se cause
138 problems, but it can complicate subclassing and, for example, plugin
139 classes that are included via multiple inheritance by loading them as
142 The C<namespace::clean> pragma will remove all previously declared or
143 imported symbols at the end of the current package's compile cycle.
144 Functions called in the package itself will still be bound by their
145 name, but they won't show up as methods on your class or instances.
147 By unimporting via C<no> you can tell C<namespace::clean> to start
148 collecting functions for the next C<use namespace::clean;> specification.
150 You can use the C<-except> flag to tell C<namespace::clean> that you
151 don't want it to remove a certain function or method. A common use would
152 be a module exporting an C<import> method along with some functions:
154 use ModuleExportingImport;
155 use namespace::clean -except => [qw( import )];
157 If you just want to C<-except> a single sub, you can pass it directly.
158 For more than one value you have to use an array reference.
160 =head2 Explicitly removing functions when your scope is compiled
162 It is also possible to explicitly tell C<namespace::clean> what packages
163 to remove when the surrounding scope has finished compiling. Here is an
169 # blessed NOT available
172 use Scalar::Util qw( blessed );
173 use namespace::clean qw( blessed );
176 return blessed shift;
179 # blessed NOT available
183 When using C<namespace::clean> together with L<Moose> you want to keep
184 the installed C<meta> method. So your classes should look like:
188 use namespace::clean -except => 'meta';
191 Same goes for L<Moose::Role>.
193 =head2 Cleaning other packages
195 You can tell C<namespace::clean> that you want to clean up another package
196 instead of the one importing. To do this you have to pass in the C<-cleanee>
199 package My::MooseX::namespace::clean;
202 use namespace::clean (); # no cleanup, just load
205 namespace::clean->import(
206 -cleanee => scalar(caller),
211 If you don't care about C<namespace::clean>s discover-and-C<-except> logic, and
212 just want to remove subroutines, try L</clean_subroutines>.
216 =head2 clean_subroutines
218 This exposes the actual subroutine-removal logic.
220 namespace::clean->clean_subroutines($cleanee, qw( subA subB ));
222 will remove C<subA> and C<subB> from C<$cleanee>. Note that this will remove the
223 subroutines B<immediately> and not wait for scope end. If you want to have this
224 effect at a specific time (e.g. C<namespace::clean> acts on scope compile end)
225 it is your responsibility to make sure it runs at that time.
229 # Constant to optimise away the unused code branches
230 use constant FIXUP_NEEDED => $] < 5.015_005_1;
231 use constant FIXUP_RENAME_SUB => $] > 5.008_008_9 && $] < 5.013_006_1;
234 delete ${__PACKAGE__."::"}{FIXUP_NEEDED};
235 delete ${__PACKAGE__."::"}{FIXUP_RENAME_SUB};
238 # Debugger fixup necessary before perl 5.15.5
240 # In perl 5.8.9-5.12, it assumes that sub_fullname($sub) can
241 # always be used to find the CV again.
242 # In perl 5.8.8 and 5.14, it assumes that the name of the glob
243 # passed to entersub can be used to find the CV.
244 # since we are deleting the glob where the subroutine was originally
245 # defined, those assumptions no longer hold.
247 # So in 5.8.9-5.12 we need to move it elsewhere and point the
248 # CV's name to the new glob.
250 # In 5.8.8 and 5.14 we move it elsewhere and rename the
251 # original glob by assigning the new glob back to it.
252 my $sub_utils_loaded;
253 my $DebuggerFixup = sub {
254 my ($f, $sub, $cleanee_stash, $deleted_stash) = @_;
256 if (FIXUP_RENAME_SUB) {
257 if (! defined $sub_utils_loaded ) {
258 $sub_utils_loaded = do {
260 # when changing version also change in Makefile.PL
262 eval { require Sub::Name; Sub::Name->VERSION($sn_ver) }
263 or die "Sub::Name $sn_ver required when running under -d or equivalent: $@";
265 # when changing version also change in Makefile.PL
267 eval { require Sub::Identify; Sub::Identify->VERSION($si_ver) }
268 or die "Sub::Identify $si_ver required when running under -d or equivalent: $@";
274 if ( Sub::Identify::sub_fullname($sub) eq ($cleanee_stash->name . "::$f") ) {
275 my $new_fq = $deleted_stash->name . "::$f";
276 Sub::Name::subname($new_fq, $sub);
277 $deleted_stash->add_symbol("&$f", $sub);
281 $deleted_stash->add_symbol("&$f", $sub);
285 my $RemoveSubs = sub {
288 my $cleanee_stash = Package::Stash->new($cleanee);
294 # ignore already removed symbols
295 next SYMBOL if $store->{exclude}{ $f };
297 my $sub = $cleanee_stash->get_symbol("&$f")
300 my $need_debugger_fixup =
305 ref(my $globref = \$cleanee_stash->namespace->{$f}) eq 'GLOB'
308 if (FIXUP_NEEDED && $need_debugger_fixup) {
309 # convince the Perl debugger to work
310 # see the comment on top of $DebuggerFixup
315 $deleted_stash ||= Package::Stash->new("namespace::clean::deleted::$cleanee"),
321 my $def = $cleanee_stash->get_symbol($name);
322 defined($def) ? [$name, $def] : ()
325 $cleanee_stash->remove_glob($f);
327 # if this perl needs no renaming trick we need to
328 # rename the original glob after the fact
329 # (see commend of $DebuggerFixup
330 if (FIXUP_NEEDED && !FIXUP_RENAME_SUB && $need_debugger_fixup) {
331 *$globref = $deleted_stash->namespace->{$f};
334 $cleanee_stash->add_symbol(@$_) for @symbols;
338 sub clean_subroutines {
339 my ($nc, $cleanee, @subs) = @_;
340 $RemoveSubs->($cleanee, {}, @subs);
345 Makes a snapshot of the current defined functions and installs a
346 L<B::Hooks::EndOfScope> hook in the current scope to invoke the cleanups.
351 my ($pragma, @args) = @_;
353 my (%args, $is_explicit);
358 if ($args[0] =~ /^\-/) {
359 my $key = shift @args;
360 my $value = shift @args;
361 $args{ $key } = $value;
369 my $cleanee = exists $args{ -cleanee } ? $args{ -cleanee } : scalar caller;
372 $RemoveSubs->($cleanee, {}, @args);
377 # calling class, all current functions and our storage
378 my $functions = $pragma->get_functions($cleanee);
379 my $store = $pragma->get_class_store($cleanee);
380 my $stash = Package::Stash->new($cleanee);
382 # except parameter can be array ref or single value
383 my %except = map {( $_ => 1 )} (
385 ? ( ref $args{ -except } eq 'ARRAY' ? @{ $args{ -except } } : $args{ -except } )
389 # register symbols for removal, if they have a CODE entry
390 for my $f (keys %$functions) {
391 next if $except{ $f };
392 next unless $stash->has_symbol("&$f");
393 $store->{remove}{ $f } = 1;
396 # register EOF handler on first call to import
397 unless ($store->{handler_is_installed}) {
399 $RemoveSubs->($cleanee, $store, keys %{ $store->{remove} });
401 $store->{handler_is_installed} = 1;
410 This method will be called when you do a
414 It will start a new section of code that defines functions to clean up.
419 my ($pragma, %args) = @_;
421 # the calling class, the current functions and our storage
422 my $cleanee = exists $args{ -cleanee } ? $args{ -cleanee } : scalar caller;
423 my $functions = $pragma->get_functions($cleanee);
424 my $store = $pragma->get_class_store($cleanee);
426 # register all unknown previous functions as excluded
427 for my $f (keys %$functions) {
428 next if $store->{remove}{ $f }
429 or $store->{exclude}{ $f };
430 $store->{exclude}{ $f } = 1;
436 =head2 get_class_store
438 This returns a reference to a hash in a passed package containing
439 information about function names included and excluded from removal.
443 sub get_class_store {
444 my ($pragma, $class) = @_;
445 my $stash = Package::Stash->new($class);
446 my $var = "%$STORAGE_VAR";
447 $stash->add_symbol($var, {})
448 unless $stash->has_symbol($var);
449 return $stash->get_symbol($var);
454 Takes a class as argument and returns all currently defined functions
455 in it as a hash reference with the function name as key and a typeglob
456 reference to the symbol as value.
461 my ($pragma, $class) = @_;
463 my $stash = Package::Stash->new($class);
465 map { $_ => $stash->get_symbol("&$_") }
466 $stash->list_all_symbols('CODE')
470 =head1 IMPLEMENTATION DETAILS
472 This module works through the effect that a
474 delete $SomePackage::{foo};
476 will remove the C<foo> symbol from C<$SomePackage> for run time lookups
477 (e.g., method calls) but will leave the entry alive to be called by
478 already resolved names in the package itself. C<namespace::clean> will
479 restore and therefor in effect keep all glob slots that aren't C<CODE>.
481 A test file has been added to the perl core to ensure that this behaviour
482 will be stable in future releases.
484 Just for completeness sake, if you want to remove the symbol completely,
485 use C<undef> instead.
489 This module is fully functional in a pure-perl environment, where
490 L<B::Hooks::EndOfScope> (with the XS dependency L<Variable::Magic>), may
491 not be available. However in this case this module falls back to a
492 L<tie()|perlfunc/tie> of L<%^H|perlvar/%^H> which may or may not interfere
493 with some crack you may be doing independently of namespace::clean.
495 If you want to ensure that your codebase is protected from this unlikely
496 clash, you need to explicitly depend on L<B::Hooks::EndOfScope>.
500 L<B::Hooks::EndOfScope>
504 Many thanks to Matt S Trout for the inspiration on the whole idea.
512 Robert 'phaylon' Sedlacek <rs@474.at>
516 Florian Ragwitz <rafl@debian.org>
520 Jesse Luehrs <doy@tozt.net>
524 Peter Rabbitson <ribasushi@cpan.org>
528 =head1 COPYRIGHT AND LICENSE
530 This software is copyright (c) 2011 by Robert 'phaylon' Sedlacek.
532 This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.
537 'Danger! Laws of Thermodynamics may not apply.'