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';
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 RENAME_SUB => $] > 5.008_008_9 && $] < 5.013_006_1;
231 { no strict; delete ${__PACKAGE__."::"}{RENAME_SUB} }
233 # In perl 5.8.9-5.12, it assumes that sub_fullname($sub) can
234 # always be used to find the CV again.
235 # In perl 5.8.8 and 5.14, it assumes that the name of the glob
236 # passed to entersub can be used to find the CV.
237 # since we are deleting the glob where the subroutine was originally
238 # defined, those assumptions no longer hold.
240 # So in 5.8.9-5.12 we need to move it elsewhere and point the
241 # CV's name to the new glob.
243 # In 5.8.8 and 5.14 we move it elsewhere and rename the
244 # original glob by assigning the new glob back to it.
245 my $sub_utils_loaded;
246 my $DebuggerFixup = sub {
247 my ($f, $sub, $cleanee_stash, $deleted_stash) = @_;
250 if (! defined $sub_utils_loaded ) {
251 $sub_utils_loaded = do {
253 # when changing version also change in Makefile.PL
255 eval { require Sub::Name; Sub::Name->VERSION($sn_ver) }
256 or die "Sub::Name $sn_ver required when running under -d or equivalent: $@";
258 # when changing version also change in Makefile.PL
260 eval { require Sub::Identify; Sub::Identify->VERSION($si_ver) }
261 or die "Sub::Identify $si_ver required when running under -d or equivalent: $@";
267 if ( Sub::Identify::sub_fullname($sub) eq ($cleanee_stash->name . "::$f") ) {
268 my $new_fq = $deleted_stash->name . "::$f";
269 Sub::Name::subname($new_fq, $sub);
270 $deleted_stash->add_symbol("&$f", $sub);
274 $deleted_stash->add_symbol("&$f", $sub);
278 my $RemoveSubs = sub {
281 my $cleanee_stash = Package::Stash->new($cleanee);
287 # ignore already removed symbols
288 next SYMBOL if $store->{exclude}{ $f };
290 my $sub = $cleanee_stash->get_symbol("&$f")
293 my $need_debugger_fixup =
296 ref(my $globref = \$cleanee_stash->namespace->{$f}) eq 'GLOB'
299 if ($need_debugger_fixup) {
300 # convince the Perl debugger to work
301 # see the comment on top of $DebuggerFixup
306 $deleted_stash ||= Package::Stash->new("namespace::clean::deleted::$cleanee"),
312 my $def = $cleanee_stash->get_symbol($name);
313 defined($def) ? [$name, $def] : ()
316 $cleanee_stash->remove_glob($f);
318 # if this perl needs no renaming trick we need to
319 # rename the original glob after the fact
320 # (see commend of $DebuggerFixup
321 if (!RENAME_SUB && $need_debugger_fixup) {
322 *$globref = $deleted_stash->namespace->{$f};
325 $cleanee_stash->add_symbol(@$_) for @symbols;
329 sub clean_subroutines {
330 my ($nc, $cleanee, @subs) = @_;
331 $RemoveSubs->($cleanee, {}, @subs);
336 Makes a snapshot of the current defined functions and installs a
337 L<B::Hooks::EndOfScope> hook in the current scope to invoke the cleanups.
342 my ($pragma, @args) = @_;
344 my (%args, $is_explicit);
349 if ($args[0] =~ /^\-/) {
350 my $key = shift @args;
351 my $value = shift @args;
352 $args{ $key } = $value;
360 my $cleanee = exists $args{ -cleanee } ? $args{ -cleanee } : scalar caller;
363 $RemoveSubs->($cleanee, {}, @args);
368 # calling class, all current functions and our storage
369 my $functions = $pragma->get_functions($cleanee);
370 my $store = $pragma->get_class_store($cleanee);
371 my $stash = Package::Stash->new($cleanee);
373 # except parameter can be array ref or single value
374 my %except = map {( $_ => 1 )} (
376 ? ( ref $args{ -except } eq 'ARRAY' ? @{ $args{ -except } } : $args{ -except } )
380 # register symbols for removal, if they have a CODE entry
381 for my $f (keys %$functions) {
382 next if $except{ $f };
383 next unless $stash->has_symbol("&$f");
384 $store->{remove}{ $f } = 1;
387 # register EOF handler on first call to import
388 unless ($store->{handler_is_installed}) {
390 $RemoveSubs->($cleanee, $store, keys %{ $store->{remove} });
392 $store->{handler_is_installed} = 1;
401 This method will be called when you do a
405 It will start a new section of code that defines functions to clean up.
410 my ($pragma, %args) = @_;
412 # the calling class, the current functions and our storage
413 my $cleanee = exists $args{ -cleanee } ? $args{ -cleanee } : scalar caller;
414 my $functions = $pragma->get_functions($cleanee);
415 my $store = $pragma->get_class_store($cleanee);
417 # register all unknown previous functions as excluded
418 for my $f (keys %$functions) {
419 next if $store->{remove}{ $f }
420 or $store->{exclude}{ $f };
421 $store->{exclude}{ $f } = 1;
427 =head2 get_class_store
429 This returns a reference to a hash in a passed package containing
430 information about function names included and excluded from removal.
434 sub get_class_store {
435 my ($pragma, $class) = @_;
436 my $stash = Package::Stash->new($class);
437 my $var = "%$STORAGE_VAR";
438 $stash->add_symbol($var, {})
439 unless $stash->has_symbol($var);
440 return $stash->get_symbol($var);
445 Takes a class as argument and returns all currently defined functions
446 in it as a hash reference with the function name as key and a typeglob
447 reference to the symbol as value.
452 my ($pragma, $class) = @_;
454 my $stash = Package::Stash->new($class);
456 map { $_ => $stash->get_symbol("&$_") }
457 $stash->list_all_symbols('CODE')
461 =head1 IMPLEMENTATION DETAILS
463 This module works through the effect that a
465 delete $SomePackage::{foo};
467 will remove the C<foo> symbol from C<$SomePackage> for run time lookups
468 (e.g., method calls) but will leave the entry alive to be called by
469 already resolved names in the package itself. C<namespace::clean> will
470 restore and therefor in effect keep all glob slots that aren't C<CODE>.
472 A test file has been added to the perl core to ensure that this behaviour
473 will be stable in future releases.
475 Just for completeness sake, if you want to remove the symbol completely,
476 use C<undef> instead.
480 This module is fully functional in a pure-perl environment, where
481 L<B::Hooks::EndOfScope> (with the XS dependency L<Variable::Magic>), may
482 not be available. However in this case this module falls back to a
483 L<tie()|perlfunc/tie> of L<%^H|perlvar/%^H> which may or may not interfere
484 with some crack you may be doing independently of namespace::clean.
486 If you want to ensure that your codebase is protected from this unlikely
487 clash, you need to explicitly depend on L<B::Hooks::EndOfScope>.
491 L<B::Hooks::EndOfScope>
495 Many thanks to Matt S Trout for the inspiration on the whole idea.
503 Robert 'phaylon' Sedlacek <rs@474.at>
507 Florian Ragwitz <rafl@debian.org>
511 Jesse Luehrs <doy@tozt.net>
515 Peter Rabbitson <ribasushi@cpan.org>
519 =head1 COPYRIGHT AND LICENSE
521 This software is copyright (c) 2011 by Robert 'phaylon' Sedlacek.
523 This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.
528 'Danger! Laws of Thermodynamics may not apply.'