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 );
13 use Symbol qw( qualify_to_ref );
23 $STORAGE_VAR = '__NAMESPACE_CLEAN_STORAGE';
24 $SCOPE_HOOK_KEY = 'namespace_clean_SCOPING';
32 use Carp qw(croak); # 'croak' will be removed
34 sub bar { 23 } # 'bar' will be removed
36 # remove all previously defined functions
39 sub baz { bar() } # 'baz' still defined, 'bar' still bound
41 # begin to collection function names from here again
44 sub quux { baz() } # 'quux' will be removed
46 # remove all functions defined after the 'no' unimport
49 # Will print: 'No', 'No', 'Yes' and 'No'
50 print +(__PACKAGE__->can('croak') ? 'Yes' : 'No'), "\n";
51 print +(__PACKAGE__->can('bar') ? 'Yes' : 'No'), "\n";
52 print +(__PACKAGE__->can('baz') ? 'Yes' : 'No'), "\n";
53 print +(__PACKAGE__->can('quux') ? 'Yes' : 'No'), "\n";
59 When you define a function, or import one, into a Perl package, it will
60 naturally also be available as a method. This does not per se cause
61 problems, but it can complicate subclassing and, for example, plugin
62 classes that are included via multiple inheritance by loading them as
65 The C<namespace::clean> pragma will remove all previously declared or
66 imported symbols at the end of the current package's compile cycle.
67 Functions called in the package itself will still be bound by their
68 name, but they won't show up as methods on your class or instances.
70 By unimporting via C<no> you can tell C<namespace::clean> to start
71 collecting functions for the next C<use namespace::clean;> specification.
73 You can use the C<-except> flag to tell C<namespace::clean> that you
74 don't want it to remove a certain function or method. A common use would
75 be a module exporting an C<import> method along with some functions:
77 use ModuleExportingImport;
78 use namespace::clean -except => [qw( import )];
80 If you just want to C<-except> a single sub, you can pass it directly.
81 For more than one value you have to use an array reference.
85 When using C<namespace::clean> together with L<Moose> you want to keep
86 the installed C<meta> method. So your classes should look like:
90 use namespace::clean -except => 'meta';
93 Same goes for L<Moose::Role>.
97 You shouldn't need to call any of these. Just C<use> the package at the
104 Makes a snapshot of the current defined functions and installs a
105 L<Scope::Guard> in the current scope to invoke the cleanups.
110 my ($pragma, %args) = @_;
112 # calling class, all current functions and our storage
113 my $cleanee = caller;
114 my $functions = $pragma->get_functions($cleanee);
115 my $store = $pragma->get_class_store($cleanee);
117 # except parameter can be array ref or single value
118 my %except = map {( $_ => 1 )} (
120 ? ( ref $args{ -except } eq 'ARRAY' ? @{ $args{ -except } } : $args{ -except } )
124 # register symbols for removal, if they have a CODE entry
125 for my $f (keys %$functions) {
126 next if $except{ $f };
127 next unless $functions->{ $f }
128 and *{ $functions->{ $f } }{CODE};
129 $store->{remove}{ $f } = 1;
132 # register EOF handler on first call to import
133 unless ($store->{handler_is_installed}) {
135 $^H{ $SCOPE_HOOK_KEY } = Scope::Guard->new(sub {
137 for my $f (keys %{ $store->{remove} }) {
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 };
157 $store->{handler_is_installed} = 1;
165 This method will be called when you do a
169 It will start a new section of code that defines functions to clean up.
176 # the calling class, the current functions and our storage
177 my $cleanee = caller;
178 my $functions = $pragma->get_functions($cleanee);
179 my $store = $pragma->get_class_store($cleanee);
181 # register all unknown previous functions as excluded
182 for my $f (keys %$functions) {
183 next if $store->{remove}{ $f }
184 or $store->{exclude}{ $f };
185 $store->{exclude}{ $f } = 1;
191 =head2 get_class_store
193 This returns a reference to a hash in a passed package containing
194 information about function names included and excluded from removal.
198 sub get_class_store {
199 my ($pragma, $class) = @_;
201 return \%{ "${class}::${STORAGE_VAR}" };
206 Takes a class as argument and returns all currently defined functions
207 in it as a hash reference with the function name as key and a typeglob
208 reference to the symbol as value.
213 my ($pragma, $class) = @_;
216 map { @$_ } # key => value
217 grep { *{ $_->[1] }{CODE} } # only functions
218 map { [$_, qualify_to_ref( $_, $class )] } # get globref
219 grep { $_ !~ /::$/ } # no packages
220 do { no strict 'refs'; keys %{ "${class}::" } } # symbol entries
224 =head1 IMPLEMENTATION DETAILS
226 This module works through the effect that a
228 delete $SomePackage::{foo};
230 will remove the C<foo> symbol from C<$SomePackage> for run time lookups
231 (e.g., method calls) but will leave the entry alive to be called by
232 already resolved names in the package itself. C<namespace::clean> will
233 restore and therefor in effect keep all glob slots that aren't C<CODE>.
235 A test file has been added to the perl core to ensure that this behaviour
236 will be stable in future releases.
238 Just for completeness sake, if you want to remove the symbol completely,
239 use C<undef> instead.
245 =head1 AUTHOR AND COPYRIGHT
247 Robert 'phaylon' Sedlacek C<E<lt>rs@474.atE<gt>>, with many thanks to
248 Matt S Trout for the inspiration on the whole idea.
252 This program is free software; you can redistribute it and/or modify
253 it under the same terms as perl itself.