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 );
23 $STORAGE_VAR = '__NAMESPACE_CLEAN_STORAGE';
24 $SCOPE_HOOK_KEY = 'namespace_clean_SCOPING';
25 $SCOPE_EXPLICIT = 'namespace_clean_EXPLICIT';
33 use Carp qw(croak); # 'croak' will be removed
35 sub bar { 23 } # 'bar' will be removed
37 # remove all previously defined functions
40 sub baz { bar() } # 'baz' still defined, 'bar' still bound
42 # begin to collection function names from here again
45 sub quux { baz() } # 'quux' will be removed
47 # remove all functions defined after the 'no' unimport
50 # Will print: 'No', 'No', 'Yes' and 'No'
51 print +(__PACKAGE__->can('croak') ? 'Yes' : 'No'), "\n";
52 print +(__PACKAGE__->can('bar') ? 'Yes' : 'No'), "\n";
53 print +(__PACKAGE__->can('baz') ? 'Yes' : 'No'), "\n";
54 print +(__PACKAGE__->can('quux') ? 'Yes' : 'No'), "\n";
60 =head2 Keeping packages clean
62 When you define a function, or import one, into a Perl package, it will
63 naturally also be available as a method. This does not per se cause
64 problems, but it can complicate subclassing and, for example, plugin
65 classes that are included via multiple inheritance by loading them as
68 The C<namespace::clean> pragma will remove all previously declared or
69 imported symbols at the end of the current package's compile cycle.
70 Functions called in the package itself will still be bound by their
71 name, but they won't show up as methods on your class or instances.
73 By unimporting via C<no> you can tell C<namespace::clean> to start
74 collecting functions for the next C<use namespace::clean;> specification.
76 You can use the C<-except> flag to tell C<namespace::clean> that you
77 don't want it to remove a certain function or method. A common use would
78 be a module exporting an C<import> method along with some functions:
80 use ModuleExportingImport;
81 use namespace::clean -except => [qw( import )];
83 If you just want to C<-except> a single sub, you can pass it directly.
84 For more than one value you have to use an array reference.
86 =head2 Explicitely removing functions when your scope is compiled
88 It is also possible to explicitely tell C<namespace::clean> what packages
89 to remove when the surrounding scope has finished compiling. Here is an
95 # blessed NOT available
98 use Scalar::Util qw( blessed );
99 use namespace::clean qw( blessed );
102 return blessed shift;
105 # blessed NOT available
109 When using C<namespace::clean> together with L<Moose> you want to keep
110 the installed C<meta> method. So your classes should look like:
114 use namespace::clean -except => 'meta';
117 Same goes for L<Moose::Role>.
121 You shouldn't need to call any of these. Just C<use> the package at the
128 Makes a snapshot of the current defined functions and installs a
129 L<Scope::Guard> in the current scope to invoke the cleanups.
133 my $RemoveSubs = sub {
139 # ignore already removed symbols
140 next SYMBOL if $store->{exclude}{ $f };
143 # keep original value to restore non-code slots
144 { no warnings 'uninitialized'; # fix possible unimports
145 local *__tmp = *{ ${ "${cleanee}::" }{ $f } };
146 delete ${ "${cleanee}::" }{ $f };
150 # restore non-code slots to symbol
151 for my $t (qw( SCALAR ARRAY HASH IO FORMAT )) {
152 next SLOT unless defined *__tmp{ $t };
153 *{ "${cleanee}::$f" } = *__tmp{ $t };
159 my ($pragma, @args) = @_;
162 my (%args, $is_explicit);
163 if (@args and $args[0] =~ /^\-/) {
171 my $cleanee = caller;
173 $^H{ $SCOPE_EXPLICIT } = Scope::Guard->new(sub {
174 $RemoveSubs->($cleanee, {}, @args);
179 # calling class, all current functions and our storage
180 my $functions = $pragma->get_functions($cleanee);
181 my $store = $pragma->get_class_store($cleanee);
183 # except parameter can be array ref or single value
184 my %except = map {( $_ => 1 )} (
186 ? ( ref $args{ -except } eq 'ARRAY' ? @{ $args{ -except } } : $args{ -except } )
190 # register symbols for removal, if they have a CODE entry
191 for my $f (keys %$functions) {
192 next if $except{ $f };
193 next unless $functions->{ $f }
194 and *{ $functions->{ $f } }{CODE};
195 $store->{remove}{ $f } = 1;
198 # register EOF handler on first call to import
199 unless ($store->{handler_is_installed}) {
200 $^H{ $SCOPE_HOOK_KEY } = Scope::Guard->new(sub {
201 $RemoveSubs->($cleanee, $store, keys %{ $store->{remove} });
203 $store->{handler_is_installed} = 1;
212 This method will be called when you do a
216 It will start a new section of code that defines functions to clean up.
223 # the calling class, the current functions and our storage
224 my $cleanee = caller;
225 my $functions = $pragma->get_functions($cleanee);
226 my $store = $pragma->get_class_store($cleanee);
228 # register all unknown previous functions as excluded
229 for my $f (keys %$functions) {
230 next if $store->{remove}{ $f }
231 or $store->{exclude}{ $f };
232 $store->{exclude}{ $f } = 1;
238 =head2 get_class_store
240 This returns a reference to a hash in a passed package containing
241 information about function names included and excluded from removal.
245 sub get_class_store {
246 my ($pragma, $class) = @_;
248 return \%{ "${class}::${STORAGE_VAR}" };
253 Takes a class as argument and returns all currently defined functions
254 in it as a hash reference with the function name as key and a typeglob
255 reference to the symbol as value.
260 my ($pragma, $class) = @_;
263 map { @$_ } # key => value
264 grep { *{ $_->[1] }{CODE} } # only functions
265 map { [$_, qualify_to_ref( $_, $class )] } # get globref
266 grep { $_ !~ /::$/ } # no packages
267 do { no strict 'refs'; keys %{ "${class}::" } } # symbol entries
271 =head1 IMPLEMENTATION DETAILS
273 This module works through the effect that a
275 delete $SomePackage::{foo};
277 will remove the C<foo> symbol from C<$SomePackage> for run time lookups
278 (e.g., method calls) but will leave the entry alive to be called by
279 already resolved names in the package itself. C<namespace::clean> will
280 restore and therefor in effect keep all glob slots that aren't C<CODE>.
282 A test file has been added to the perl core to ensure that this behaviour
283 will be stable in future releases.
285 Just for completeness sake, if you want to remove the symbol completely,
286 use C<undef> instead.
292 =head1 AUTHOR AND COPYRIGHT
294 Robert 'phaylon' Sedlacek C<E<lt>rs@474.atE<gt>>, with many thanks to
295 Matt S Trout for the inspiration on the whole idea.
299 This program is free software; you can redistribute it and/or modify
300 it under the same terms as perl itself.
305 'Danger! Laws of Thermodynamics may not apply.'