1 package namespace::clean;
5 namespace::clean - Keep imports and functions out of your namespace
12 use vars qw( $VERSION $STORAGE_VAR $SCOPE_HOOK_KEY $SCOPE_EXPLICIT );
13 use Symbol qw( qualify_to_ref );
14 use B::Hooks::EndOfScope;
23 $STORAGE_VAR = '__NAMESPACE_CLEAN_STORAGE';
31 use Carp qw(croak); # 'croak' will be removed
33 sub bar { 23 } # 'bar' will be removed
35 # remove all previously defined functions
38 sub baz { bar() } # 'baz' still defined, 'bar' still bound
40 # begin to collection function names from here again
43 sub quux { baz() } # 'quux' will be removed
45 # remove all functions defined after the 'no' unimport
48 # Will print: 'No', 'No', 'Yes' and 'No'
49 print +(__PACKAGE__->can('croak') ? 'Yes' : 'No'), "\n";
50 print +(__PACKAGE__->can('bar') ? 'Yes' : 'No'), "\n";
51 print +(__PACKAGE__->can('baz') ? 'Yes' : 'No'), "\n";
52 print +(__PACKAGE__->can('quux') ? 'Yes' : 'No'), "\n";
58 =head2 Keeping packages clean
60 When you define a function, or import one, into a Perl package, it will
61 naturally also be available as a method. This does not per se cause
62 problems, but it can complicate subclassing and, for example, plugin
63 classes that are included via multiple inheritance by loading them as
66 The C<namespace::clean> pragma will remove all previously declared or
67 imported symbols at the end of the current package's compile cycle.
68 Functions called in the package itself will still be bound by their
69 name, but they won't show up as methods on your class or instances.
71 By unimporting via C<no> you can tell C<namespace::clean> to start
72 collecting functions for the next C<use namespace::clean;> specification.
74 You can use the C<-except> flag to tell C<namespace::clean> that you
75 don't want it to remove a certain function or method. A common use would
76 be a module exporting an C<import> method along with some functions:
78 use ModuleExportingImport;
79 use namespace::clean -except => [qw( import )];
81 If you just want to C<-except> a single sub, you can pass it directly.
82 For more than one value you have to use an array reference.
84 =head2 Explicitely removing functions when your scope is compiled
86 It is also possible to explicitely tell C<namespace::clean> what packages
87 to remove when the surrounding scope has finished compiling. Here is an
93 # blessed NOT available
96 use Scalar::Util qw( blessed );
97 use namespace::clean qw( blessed );
100 return blessed shift;
103 # blessed NOT available
107 When using C<namespace::clean> together with L<Moose> you want to keep
108 the installed C<meta> method. So your classes should look like:
112 use namespace::clean -except => 'meta';
115 Same goes for L<Moose::Role>.
117 =head2 Cleaning other packages
119 You can tell C<namespace::clean> that you want to clean up another package
120 instead of the one importing. To do this you have to pass in the C<-cleanee>
123 package My::MooseX::namespace::clean;
126 use namespace::clean (); # no cleanup, just load
129 namespace::clean->import(
130 -cleanee => scalar(caller),
135 If you don't care about C<namespace::clean>s discover-and-C<-except> logic, and
136 just want to remove subroutines, try L</clean_subroutines>.
140 You shouldn't need to call any of these. Just C<use> the package at the
145 =head2 clean_subroutines
147 This exposes the actual subroutine-removal logic.
149 namespace::clean->clean_subroutines($cleanee, qw( subA subB ));
151 will remove C<subA> and C<subB> from C<$cleanee>. Note that this will remove the
152 subroutines B<immediately> and not wait for scope end. If you want to have this
153 effect at a specific time (e.g. C<namespace::clean> acts on scope compile end)
154 it is your responsibility to make sure it runs at that time.
158 my $RemoveSubs = sub {
165 # ignore already removed symbols
166 next SYMBOL if $store->{exclude}{ $f };
171 # keep original value to restore non-code slots
172 { no warnings 'uninitialized'; # fix possible unimports
173 *__tmp = *{ ${ "${cleanee}::" }{ $f } };
174 delete ${ "${cleanee}::" }{ $f };
178 # restore non-code slots to symbol.
179 # omit the FORMAT slot, since perl erroneously puts it into the
180 # SCALAR slot of the new glob.
181 for my $t (qw( SCALAR ARRAY HASH IO )) {
182 next SLOT unless defined *__tmp{ $t };
183 *{ "${cleanee}::$f" } = *__tmp{ $t };
188 sub clean_subroutines {
189 my ($nc, $cleanee, @subs) = @_;
190 $RemoveSubs->($cleanee, {}, @subs);
195 Makes a snapshot of the current defined functions and installs a
196 L<B::Hooks::EndOfScope> hook in the current scope to invoke the cleanups.
201 my ($pragma, @args) = @_;
203 my (%args, $is_explicit);
208 if ($args[0] =~ /^\-/) {
209 my $key = shift @args;
210 my $value = shift @args;
211 $args{ $key } = $value;
219 my $cleanee = exists $args{ -cleanee } ? $args{ -cleanee } : scalar caller;
222 $RemoveSubs->($cleanee, {}, @args);
227 # calling class, all current functions and our storage
228 my $functions = $pragma->get_functions($cleanee);
229 my $store = $pragma->get_class_store($cleanee);
231 # except parameter can be array ref or single value
232 my %except = map {( $_ => 1 )} (
234 ? ( ref $args{ -except } eq 'ARRAY' ? @{ $args{ -except } } : $args{ -except } )
238 # register symbols for removal, if they have a CODE entry
239 for my $f (keys %$functions) {
240 next if $except{ $f };
241 next unless $functions->{ $f }
242 and *{ $functions->{ $f } }{CODE};
243 $store->{remove}{ $f } = 1;
246 # register EOF handler on first call to import
247 unless ($store->{handler_is_installed}) {
249 $RemoveSubs->($cleanee, $store, keys %{ $store->{remove} });
251 $store->{handler_is_installed} = 1;
260 This method will be called when you do a
264 It will start a new section of code that defines functions to clean up.
269 my ($pragma, %args) = @_;
271 # the calling class, the current functions and our storage
272 my $cleanee = exists $args{ -cleanee } ? $args{ -cleanee } : scalar caller;
273 my $functions = $pragma->get_functions($cleanee);
274 my $store = $pragma->get_class_store($cleanee);
276 # register all unknown previous functions as excluded
277 for my $f (keys %$functions) {
278 next if $store->{remove}{ $f }
279 or $store->{exclude}{ $f };
280 $store->{exclude}{ $f } = 1;
286 =head2 get_class_store
288 This returns a reference to a hash in a passed package containing
289 information about function names included and excluded from removal.
293 sub get_class_store {
294 my ($pragma, $class) = @_;
296 return \%{ "${class}::${STORAGE_VAR}" };
301 Takes a class as argument and returns all currently defined functions
302 in it as a hash reference with the function name as key and a typeglob
303 reference to the symbol as value.
308 my ($pragma, $class) = @_;
311 map { @$_ } # key => value
312 grep { *{ $_->[1] }{CODE} } # only functions
313 map { [$_, qualify_to_ref( $_, $class )] } # get globref
314 grep { $_ !~ /::$/ } # no packages
315 do { no strict 'refs'; keys %{ "${class}::" } } # symbol entries
321 C<namespace::clean> will clobber any formats that have the same name as
322 a deleted sub. This is due to a bug in perl that makes it impossible to
323 re-assign the FORMAT ref into a new glob.
325 =head1 IMPLEMENTATION DETAILS
327 This module works through the effect that a
329 delete $SomePackage::{foo};
331 will remove the C<foo> symbol from C<$SomePackage> for run time lookups
332 (e.g., method calls) but will leave the entry alive to be called by
333 already resolved names in the package itself. C<namespace::clean> will
334 restore and therefor in effect keep all glob slots that aren't C<CODE>.
336 A test file has been added to the perl core to ensure that this behaviour
337 will be stable in future releases.
339 Just for completeness sake, if you want to remove the symbol completely,
340 use C<undef> instead.
344 L<B::Hooks::EndOfScope>
346 =head1 AUTHOR AND COPYRIGHT
348 Robert 'phaylon' Sedlacek C<E<lt>rs@474.atE<gt>>, with many thanks to
349 Matt S Trout for the inspiration on the whole idea.
353 This program is free software; you can redistribute it and/or modify
354 it under the same terms as perl itself.
359 'Danger! Laws of Thermodynamics may not apply.'