1 package namespace::clean;
5 namespace::clean - Keep imports and functions out of your namespace
12 use vars qw( $VERSION $STORAGE_VAR );
13 use Symbol qw( qualify_to_ref );
23 $STORAGE_VAR = '__NAMESPACE_CLEAN_STORAGE';
31 use Carp qw(croak); # 'croak' will be removed
33 sub bar { 23 } # 'bar' will be removed
35 # remove all previously defined functions
38 sub baz { bar() } # 'baz' still defined, 'bar' still bound
40 # begin to collection function names from here again
43 sub quux { baz() } # 'quux' will be removed
45 # remove all functions defined after the 'no' unimport
48 # Will print: 'No', 'No', 'Yes' and 'No'
49 print +(__PACKAGE__->can('croak') ? 'Yes' : 'No'), "\n";
50 print +(__PACKAGE__->can('bar') ? 'Yes' : 'No'), "\n";
51 print +(__PACKAGE__->can('baz') ? 'Yes' : 'No'), "\n";
52 print +(__PACKAGE__->can('quux') ? 'Yes' : 'No'), "\n";
58 When you define a function, or import one, into a Perl package, it will
59 naturally also be available as a method. This does not per se cause
60 problems, but it can complicate subclassing and, for example, plugin
61 classes that are included via multiple inheritance by loading them as
64 The C<namespace::clean> pragma will remove all previously declared or
65 imported symbols at the end of the current package's compile cycle.
66 Functions called in the package itself will still be bound by their
67 name, but they won't show up as methods on your class or instances.
69 By unimporting via C<no> you can tell C<namespace::clean> to start
70 collecting functions for the next C<use namespace::clean;> specification.
72 You can use the C<-except> flag to tell C<namespace::clean> that you
73 don't want it to remove a certain function. A common use would be a
74 module exporting an C<import> method along with some functions:
76 use ModuleExportingImport;
77 use namespace::clean -except => [qw( import )];
81 You shouldn't need to call any of these. Just C<use> the package at the
88 Makes a snapshot of the current defined functions and registers a
89 L<Filter::EOF> cleanup routine to remove those symbols at the end
95 my ($pragma, %args) = @_;
97 # calling class, all current functions and our storage
99 my $functions = $pragma->get_functions($cleanee);
100 my $store = $pragma->get_class_store($cleanee);
102 my %except = map {( $_ => 1 )} @{ $args{ -except } || [] };
104 # register symbols for removal, if they have a CODE entry
105 for my $f (keys %$functions) {
106 next if $except{ $f };
107 next unless $functions->{ $f }
108 and *{ $functions->{ $f } }{CODE};
109 $store->{remove}{ $f } = 1;
112 # register EOF handler on first call to import
113 unless ($store->{handler_is_installed}) {
114 Filter::EOF->on_eof_call(sub {
116 for my $f (keys %{ $store->{remove} }) {
118 # ignore already removed symbols
119 next SYMBOL if $store->{exclude}{ $f };
122 # keep original value to restore non-code slots
123 local *__tmp = *{ ${ "${cleanee}::" }{ $f } };
124 delete ${ "${cleanee}::" }{ $f };
127 # restore non-code slots to symbol
128 for my $t (qw( SCALAR ARRAY HASH IO FORMAT )) {
129 next SLOT unless defined *__tmp{ $t };
130 *{ "${cleanee}::$f" } = *__tmp{ $t };
134 $store->{handler_is_installed} = 1;
142 This method will be called when you do a
146 It will start a new section of code that defines functions to clean up.
153 # the calling class, the current functions and our storage
154 my $cleanee = caller;
155 my $functions = $pragma->get_functions($cleanee);
156 my $store = $pragma->get_class_store($cleanee);
158 # register all unknown previous functions as excluded
159 for my $f (keys %$functions) {
160 next if $store->{remove}{ $f }
161 or $store->{exclude}{ $f };
162 $store->{exclude}{ $f } = 1;
168 =head2 get_class_store
170 This returns a reference to a hash in a passed package containing
171 information about function names included and excluded from removal.
175 sub get_class_store {
176 my ($pragma, $class) = @_;
178 return \%{ "${class}::${STORAGE_VAR}" };
183 Takes a class as argument and returns all currently defined functions
184 in it as a hash reference with the function name as key and a typeglob
185 reference to the symbol as value.
190 my ($pragma, $class) = @_;
193 map { @$_ } # key => value
194 grep { *{ $_->[1] }{CODE} } # only functions
195 map { [$_, qualify_to_ref( $_, $class )] } # get globref
196 grep { $_ !~ /::$/ } # no packages
197 do { no strict 'refs'; keys %{ "${class}::" } } # symbol entries
201 =head1 IMPLEMENTATION DETAILS
203 This module works through the effect that a
205 delete $SomePackage::{foo};
207 will remove the C<foo> symbol from C<$SomePackage> for run time lookups
208 (e.g., method calls) but will leave the entry alive to be called by
209 already resolved names in the package itself.
211 A test file has been added to the perl core to ensure that this behaviour
212 will be stable in future releases.
214 Just for completeness sake, if you want to remove the symbol completely,
215 use C<undef> instead.
221 =head1 AUTHOR AND COPYRIGHT
223 Robert 'phaylon' Sedlacek C<E<lt>rs@474.atE<gt>>, with many thanks to
224 Matt S Trout for the inspiration on the whole idea.
228 This program is free software; you can redistribute it and/or modify
229 it under the same terms as perl itself.