1 package namespace::clean;
9 our $STORAGE_VAR = '__NAMESPACE_CLEAN_STORAGE';
11 use B::Hooks::EndOfScope 'on_scope_end';
15 namespace::clean - Keep imports and functions out of your namespace
23 use Carp qw(croak); # 'croak' will be removed
25 sub bar { 23 } # 'bar' will be removed
27 # remove all previously defined functions
30 sub baz { bar() } # 'baz' still defined, 'bar' still bound
32 # begin to collection function names from here again
35 sub quux { baz() } # 'quux' will be removed
37 # remove all functions defined after the 'no' unimport
40 # Will print: 'No', 'No', 'Yes' and 'No'
41 print +(__PACKAGE__->can('croak') ? 'Yes' : 'No'), "\n";
42 print +(__PACKAGE__->can('bar') ? 'Yes' : 'No'), "\n";
43 print +(__PACKAGE__->can('baz') ? 'Yes' : 'No'), "\n";
44 print +(__PACKAGE__->can('quux') ? 'Yes' : 'No'), "\n";
50 =head2 Keeping packages clean
52 When you define a function, or import one, into a Perl package, it will
53 naturally also be available as a method. This does not per se cause
54 problems, but it can complicate subclassing and, for example, plugin
55 classes that are included via multiple inheritance by loading them as
58 The C<namespace::clean> pragma will remove all previously declared or
59 imported symbols at the end of the current package's compile cycle.
60 Functions called in the package itself will still be bound by their
61 name, but they won't show up as methods on your class or instances.
63 By unimporting via C<no> you can tell C<namespace::clean> to start
64 collecting functions for the next C<use namespace::clean;> specification.
66 You can use the C<-except> flag to tell C<namespace::clean> that you
67 don't want it to remove a certain function or method. A common use would
68 be a module exporting an C<import> method along with some functions:
70 use ModuleExportingImport;
71 use namespace::clean -except => [qw( import )];
73 If you just want to C<-except> a single sub, you can pass it directly.
74 For more than one value you have to use an array reference.
76 =head2 Explicitly removing functions when your scope is compiled
78 It is also possible to explicitly tell C<namespace::clean> what packages
79 to remove when the surrounding scope has finished compiling. Here is an
85 # blessed NOT available
88 use Scalar::Util qw( blessed );
89 use namespace::clean qw( blessed );
95 # blessed NOT available
99 When using C<namespace::clean> together with L<Moose> you want to keep
100 the installed C<meta> method. So your classes should look like:
104 use namespace::clean -except => 'meta';
107 Same goes for L<Moose::Role>.
109 =head2 Cleaning other packages
111 You can tell C<namespace::clean> that you want to clean up another package
112 instead of the one importing. To do this you have to pass in the C<-cleanee>
115 package My::MooseX::namespace::clean;
118 use namespace::clean (); # no cleanup, just load
121 namespace::clean->import(
122 -cleanee => scalar(caller),
127 If you don't care about C<namespace::clean>s discover-and-C<-except> logic, and
128 just want to remove subroutines, try L</clean_subroutines>.
132 =head2 clean_subroutines
134 This exposes the actual subroutine-removal logic.
136 namespace::clean->clean_subroutines($cleanee, qw( subA subB ));
138 will remove C<subA> and C<subB> from C<$cleanee>. Note that this will remove the
139 subroutines B<immediately> and not wait for scope end. If you want to have this
140 effect at a specific time (e.g. C<namespace::clean> acts on scope compile end)
141 it is your responsibility to make sure it runs at that time.
145 # Constant to optimise away the unused code branches
146 use constant FIXUP_NEEDED => $] < 5.015_005_1;
147 use constant FIXUP_RENAME_SUB => $] > 5.008_008_9 && $] < 5.013_005_1;
150 delete ${__PACKAGE__."::"}{FIXUP_NEEDED};
151 delete ${__PACKAGE__."::"}{FIXUP_RENAME_SUB};
154 # Debugger fixup necessary before perl 5.15.5
156 # In perl 5.8.9-5.12, it assumes that sub_fullname($sub) can
157 # always be used to find the CV again.
158 # In perl 5.8.8 and 5.14, it assumes that the name of the glob
159 # passed to entersub can be used to find the CV.
160 # since we are deleting the glob where the subroutine was originally
161 # defined, those assumptions no longer hold.
163 # So in 5.8.9-5.12 we need to move it elsewhere and point the
164 # CV's name to the new glob.
166 # In 5.8.8 and 5.14 we move it elsewhere and rename the
167 # original glob by assigning the new glob back to it.
168 my $sub_utils_loaded;
169 my $DebuggerFixup = sub {
170 my ($f, $sub, $cleanee_stash, $deleted_stash) = @_;
172 if (FIXUP_RENAME_SUB) {
173 if (! defined $sub_utils_loaded ) {
174 $sub_utils_loaded = do {
176 # when changing version also change in Makefile.PL
178 eval { require Sub::Name; Sub::Name->VERSION($sn_ver) }
179 or die "Sub::Name $sn_ver required when running under -d or equivalent: $@";
181 # when changing version also change in Makefile.PL
183 eval { require Sub::Identify; Sub::Identify->VERSION($si_ver) }
184 or die "Sub::Identify $si_ver required when running under -d or equivalent: $@";
190 if ( Sub::Identify::sub_fullname($sub) eq ($cleanee_stash->name . "::$f") ) {
191 my $new_fq = $deleted_stash->name . "::$f";
192 Sub::Name::subname($new_fq, $sub);
193 $deleted_stash->add_symbol("&$f", $sub);
197 $deleted_stash->add_symbol("&$f", $sub);
201 my $RemoveSubs = sub {
204 my $cleanee_stash = Package::Stash->new($cleanee);
210 # ignore already removed symbols
211 next SYMBOL if $store->{exclude}{ $f };
213 my $sub = $cleanee_stash->get_symbol("&$f")
216 my $need_debugger_fixup =
221 ref(my $globref = \$cleanee_stash->namespace->{$f}) eq 'GLOB'
224 if (FIXUP_NEEDED && $need_debugger_fixup) {
225 # convince the Perl debugger to work
226 # see the comment on top of $DebuggerFixup
231 $deleted_stash ||= Package::Stash->new("namespace::clean::deleted::$cleanee"),
237 my $def = $cleanee_stash->get_symbol($name);
238 defined($def) ? [$name, $def] : ()
241 $cleanee_stash->remove_glob($f);
243 # if this perl needs no renaming trick we need to
244 # rename the original glob after the fact
245 # (see commend of $DebuggerFixup
246 if (FIXUP_NEEDED && !FIXUP_RENAME_SUB && $need_debugger_fixup) {
247 *$globref = $deleted_stash->namespace->{$f};
250 $cleanee_stash->add_symbol(@$_) for @symbols;
254 sub clean_subroutines {
255 my ($nc, $cleanee, @subs) = @_;
256 $RemoveSubs->($cleanee, {}, @subs);
261 Makes a snapshot of the current defined functions and installs a
262 L<B::Hooks::EndOfScope> hook in the current scope to invoke the cleanups.
267 my ($pragma, @args) = @_;
269 my (%args, $is_explicit);
274 if ($args[0] =~ /^\-/) {
275 my $key = shift @args;
276 my $value = shift @args;
277 $args{ $key } = $value;
285 my $cleanee = exists $args{ -cleanee } ? $args{ -cleanee } : scalar caller;
288 $RemoveSubs->($cleanee, {}, @args);
293 # calling class, all current functions and our storage
294 my $functions = $pragma->get_functions($cleanee);
295 my $store = $pragma->get_class_store($cleanee);
296 my $stash = Package::Stash->new($cleanee);
298 # except parameter can be array ref or single value
299 my %except = map {( $_ => 1 )} (
301 ? ( ref $args{ -except } eq 'ARRAY' ? @{ $args{ -except } } : $args{ -except } )
305 # register symbols for removal, if they have a CODE entry
306 for my $f (keys %$functions) {
307 next if $except{ $f };
308 next unless $stash->has_symbol("&$f");
309 $store->{remove}{ $f } = 1;
312 # register EOF handler on first call to import
313 unless ($store->{handler_is_installed}) {
315 $RemoveSubs->($cleanee, $store, keys %{ $store->{remove} });
317 $store->{handler_is_installed} = 1;
326 This method will be called when you do a
330 It will start a new section of code that defines functions to clean up.
335 my ($pragma, %args) = @_;
337 # the calling class, the current functions and our storage
338 my $cleanee = exists $args{ -cleanee } ? $args{ -cleanee } : scalar caller;
339 my $functions = $pragma->get_functions($cleanee);
340 my $store = $pragma->get_class_store($cleanee);
342 # register all unknown previous functions as excluded
343 for my $f (keys %$functions) {
344 next if $store->{remove}{ $f }
345 or $store->{exclude}{ $f };
346 $store->{exclude}{ $f } = 1;
352 =head2 get_class_store
354 This returns a reference to a hash in a passed package containing
355 information about function names included and excluded from removal.
359 sub get_class_store {
360 my ($pragma, $class) = @_;
361 my $stash = Package::Stash->new($class);
362 my $var = "%$STORAGE_VAR";
363 $stash->add_symbol($var, {})
364 unless $stash->has_symbol($var);
365 return $stash->get_symbol($var);
370 Takes a class as argument and returns all currently defined functions
371 in it as a hash reference with the function name as key and a typeglob
372 reference to the symbol as value.
377 my ($pragma, $class) = @_;
379 my $stash = Package::Stash->new($class);
381 map { $_ => $stash->get_symbol("&$_") }
382 $stash->list_all_symbols('CODE')
386 =head1 IMPLEMENTATION DETAILS
388 This module works through the effect that a
390 delete $SomePackage::{foo};
392 will remove the C<foo> symbol from C<$SomePackage> for run time lookups
393 (e.g., method calls) but will leave the entry alive to be called by
394 already resolved names in the package itself. C<namespace::clean> will
395 restore and therefor in effect keep all glob slots that aren't C<CODE>.
397 A test file has been added to the perl core to ensure that this behaviour
398 will be stable in future releases.
400 Just for completeness sake, if you want to remove the symbol completely,
401 use C<undef> instead.
405 L<B::Hooks::EndOfScope>
409 Many thanks to Matt S Trout for the inspiration on the whole idea.
417 Robert 'phaylon' Sedlacek <rs@474.at>
421 Florian Ragwitz <rafl@debian.org>
425 Jesse Luehrs <doy@tozt.net>
429 Peter Rabbitson <ribasushi@cpan.org>
433 Father Chrysostomos <sprout@cpan.org>
437 =head1 COPYRIGHT AND LICENSE
439 This software is copyright (c) 2011 by L</AUTHORS>
441 This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.
446 'Danger! Laws of Thermodynamics may not apply.'