1 package namespace::clean;
2 # ABSTRACT: Keep imports and functions out of your namespace
7 use vars qw( $STORAGE_VAR );
10 our $VERSION = '0.20_01';
12 $STORAGE_VAR = '__NAMESPACE_CLEAN_STORAGE';
16 require B::Hooks::EndOfScope;
17 B::Hooks::EndOfScope->VERSION('0.07'); # when changing also change in Makefile.PL
20 B::Hooks::EndOfScope->import('on_scope_end');
23 eval <<'PP' or die $@;
26 package namespace::clean::_ScopeGuard;
28 sub arm { bless [ $_[1] ] }
30 sub DESTROY { $_[0]->[0]->() }
35 sub on_scope_end (&) {
38 if( my $stack = tied( %^H ) ) {
39 push @$stack, namespace::clean::_ScopeGuard->arm(shift);
42 tie( %^H, 'Tie::ExtraHash', namespace::clean::_ScopeGuard->arm(shift) );
59 use Carp qw(croak); # 'croak' will be removed
61 sub bar { 23 } # 'bar' will be removed
63 # remove all previously defined functions
66 sub baz { bar() } # 'baz' still defined, 'bar' still bound
68 # begin to collection function names from here again
71 sub quux { baz() } # 'quux' will be removed
73 # remove all functions defined after the 'no' unimport
76 # Will print: 'No', 'No', 'Yes' and 'No'
77 print +(__PACKAGE__->can('croak') ? 'Yes' : 'No'), "\n";
78 print +(__PACKAGE__->can('bar') ? 'Yes' : 'No'), "\n";
79 print +(__PACKAGE__->can('baz') ? 'Yes' : 'No'), "\n";
80 print +(__PACKAGE__->can('quux') ? 'Yes' : 'No'), "\n";
86 =head2 Keeping packages clean
88 When you define a function, or import one, into a Perl package, it will
89 naturally also be available as a method. This does not per se cause
90 problems, but it can complicate subclassing and, for example, plugin
91 classes that are included via multiple inheritance by loading them as
94 The C<namespace::clean> pragma will remove all previously declared or
95 imported symbols at the end of the current package's compile cycle.
96 Functions called in the package itself will still be bound by their
97 name, but they won't show up as methods on your class or instances.
99 By unimporting via C<no> you can tell C<namespace::clean> to start
100 collecting functions for the next C<use namespace::clean;> specification.
102 You can use the C<-except> flag to tell C<namespace::clean> that you
103 don't want it to remove a certain function or method. A common use would
104 be a module exporting an C<import> method along with some functions:
106 use ModuleExportingImport;
107 use namespace::clean -except => [qw( import )];
109 If you just want to C<-except> a single sub, you can pass it directly.
110 For more than one value you have to use an array reference.
112 =head2 Explicitly removing functions when your scope is compiled
114 It is also possible to explicitly tell C<namespace::clean> what packages
115 to remove when the surrounding scope has finished compiling. Here is an
121 # blessed NOT available
124 use Scalar::Util qw( blessed );
125 use namespace::clean qw( blessed );
128 return blessed shift;
131 # blessed NOT available
135 When using C<namespace::clean> together with L<Moose> you want to keep
136 the installed C<meta> method. So your classes should look like:
140 use namespace::clean -except => 'meta';
143 Same goes for L<Moose::Role>.
145 =head2 Cleaning other packages
147 You can tell C<namespace::clean> that you want to clean up another package
148 instead of the one importing. To do this you have to pass in the C<-cleanee>
151 package My::MooseX::namespace::clean;
154 use namespace::clean (); # no cleanup, just load
157 namespace::clean->import(
158 -cleanee => scalar(caller),
163 If you don't care about C<namespace::clean>s discover-and-C<-except> logic, and
164 just want to remove subroutines, try L</clean_subroutines>.
168 =head2 clean_subroutines
170 This exposes the actual subroutine-removal logic.
172 namespace::clean->clean_subroutines($cleanee, qw( subA subB ));
174 will remove C<subA> and C<subB> from C<$cleanee>. Note that this will remove the
175 subroutines B<immediately> and not wait for scope end. If you want to have this
176 effect at a specific time (e.g. C<namespace::clean> acts on scope compile end)
177 it is your responsibility to make sure it runs at that time.
181 my $sub_utils_loaded;
182 my $DebuggerRename = sub {
183 my ($f, $sub, $cleanee_stash, $deleted_stash) = @_;
185 if (! defined $sub_utils_loaded ) {
186 $sub_utils_loaded = do {
188 eval { require Sub::Name; Sub::Name->VERSION($sn_ver) }
189 or die "Sub::Name $sn_ver required when running under -d or equivalent: $@";
192 eval { require Sub::Identify; Sub::Identify->VERSION($si_ver) }
193 or die "Sub::Identify $si_ver required when running under -d or equivalent: $@";
199 if ( Sub::Identify::sub_fullname($sub) eq ($cleanee_stash->name . "::$f") ) {
200 my $new_fq = $deleted_stash->name . "::$f";
201 Sub::Name::subname($new_fq, $sub);
202 $deleted_stash->add_symbol("&$f", $sub);
206 my $RemoveSubs = sub {
209 my $cleanee_stash = Package::Stash->new($cleanee);
215 # ignore already removed symbols
216 next SYMBOL if $store->{exclude}{ $f };
218 my $sub = $cleanee_stash->get_symbol("&$f")
221 if ($^P and ref(\$cleanee_stash->namespace->{$f}) eq 'GLOB') {
222 # convince the Perl debugger to work
223 # it assumes that sub_fullname($sub) can always be used to find the CV again
224 # since we are deleting the glob where the subroutine was originally
225 # defined, that assumption no longer holds, so we need to move it
226 # elsewhere and point the CV's name to the new glob.
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 $cleanee_stash->add_symbol(@$_) for @symbols;
247 sub clean_subroutines {
248 my ($nc, $cleanee, @subs) = @_;
249 $RemoveSubs->($cleanee, {}, @subs);
254 Makes a snapshot of the current defined functions and installs a
255 L<B::Hooks::EndOfScope> hook in the current scope to invoke the cleanups.
260 my ($pragma, @args) = @_;
262 my (%args, $is_explicit);
267 if ($args[0] =~ /^\-/) {
268 my $key = shift @args;
269 my $value = shift @args;
270 $args{ $key } = $value;
278 my $cleanee = exists $args{ -cleanee } ? $args{ -cleanee } : scalar caller;
281 $RemoveSubs->($cleanee, {}, @args);
286 # calling class, all current functions and our storage
287 my $functions = $pragma->get_functions($cleanee);
288 my $store = $pragma->get_class_store($cleanee);
289 my $stash = Package::Stash->new($cleanee);
291 # except parameter can be array ref or single value
292 my %except = map {( $_ => 1 )} (
294 ? ( ref $args{ -except } eq 'ARRAY' ? @{ $args{ -except } } : $args{ -except } )
298 # register symbols for removal, if they have a CODE entry
299 for my $f (keys %$functions) {
300 next if $except{ $f };
301 next unless $stash->has_symbol("&$f");
302 $store->{remove}{ $f } = 1;
305 # register EOF handler on first call to import
306 unless ($store->{handler_is_installed}) {
308 $RemoveSubs->($cleanee, $store, keys %{ $store->{remove} });
310 $store->{handler_is_installed} = 1;
319 This method will be called when you do a
323 It will start a new section of code that defines functions to clean up.
328 my ($pragma, %args) = @_;
330 # the calling class, the current functions and our storage
331 my $cleanee = exists $args{ -cleanee } ? $args{ -cleanee } : scalar caller;
332 my $functions = $pragma->get_functions($cleanee);
333 my $store = $pragma->get_class_store($cleanee);
335 # register all unknown previous functions as excluded
336 for my $f (keys %$functions) {
337 next if $store->{remove}{ $f }
338 or $store->{exclude}{ $f };
339 $store->{exclude}{ $f } = 1;
345 =head2 get_class_store
347 This returns a reference to a hash in a passed package containing
348 information about function names included and excluded from removal.
352 sub get_class_store {
353 my ($pragma, $class) = @_;
354 my $stash = Package::Stash->new($class);
355 my $var = "%$STORAGE_VAR";
356 $stash->add_symbol($var, {})
357 unless $stash->has_symbol($var);
358 return $stash->get_symbol($var);
363 Takes a class as argument and returns all currently defined functions
364 in it as a hash reference with the function name as key and a typeglob
365 reference to the symbol as value.
370 my ($pragma, $class) = @_;
372 my $stash = Package::Stash->new($class);
374 map { $_ => $stash->get_symbol("&$_") }
375 $stash->list_all_symbols('CODE')
379 =head1 IMPLEMENTATION DETAILS
381 This module works through the effect that a
383 delete $SomePackage::{foo};
385 will remove the C<foo> symbol from C<$SomePackage> for run time lookups
386 (e.g., method calls) but will leave the entry alive to be called by
387 already resolved names in the package itself. C<namespace::clean> will
388 restore and therefor in effect keep all glob slots that aren't C<CODE>.
390 A test file has been added to the perl core to ensure that this behaviour
391 will be stable in future releases.
393 Just for completeness sake, if you want to remove the symbol completely,
394 use C<undef> instead.
398 This module is fully functional in a pure-perl environment, where
399 L<Variable::Magic>, a L<B::Hooks::EndOfScope> dependency, may not be
400 available. However in this case this module falls back to a
401 L<tie()|perlfunc/tie> of L<%^H|perlvar/%^H> which may or may not interfere
402 with some crack you may be doing independently of namespace::clean.
406 L<B::Hooks::EndOfScope>
410 Many thanks to Matt S Trout for the inspiration on the whole idea.
418 Robert 'phaylon' Sedlacek <rs@474.at>
422 Florian Ragwitz <rafl@debian.org>
426 Jesse Luehrs <doy@tozt.net>
430 Peter Rabbitson <ribasushi@cpan.org>
434 =head1 COPYRIGHT AND LICENSE
436 This software is copyright (c) 2011 by Robert 'phaylon' Sedlacek.
438 This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.
443 'Danger! Laws of Thermodynamics may not apply.'