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 or method. A common use would
74 be a module exporting an C<import> method along with some functions:
76 use ModuleExportingImport;
77 use namespace::clean -except => [qw( import )];
79 If you just want to C<-except> a single sub, you can pass it directly.
80 For more than one value you have to use an array reference.
84 You shouldn't need to call any of these. Just C<use> the package at the
91 Makes a snapshot of the current defined functions and registers a
92 L<Filter::EOF> cleanup routine to remove those symbols at the end
98 my ($pragma, %args) = @_;
100 # calling class, all current functions and our storage
101 my $cleanee = caller;
102 my $functions = $pragma->get_functions($cleanee);
103 my $store = $pragma->get_class_store($cleanee);
105 # except parameter can be array ref or single value
106 my %except = map {( $_ => 1 )} (
108 ? ( ref $args{ -except } eq 'ARRAY' ? @{ $args{ -except } } : $args{ -except } )
112 # register symbols for removal, if they have a CODE entry
113 for my $f (keys %$functions) {
114 next if $except{ $f };
115 next unless $functions->{ $f }
116 and *{ $functions->{ $f } }{CODE};
117 $store->{remove}{ $f } = 1;
120 # register EOF handler on first call to import
121 unless ($store->{handler_is_installed}) {
122 Filter::EOF->on_eof_call(sub {
124 for my $f (keys %{ $store->{remove} }) {
126 # ignore already removed symbols
127 next SYMBOL if $store->{exclude}{ $f };
130 # keep original value to restore non-code slots
131 { no warnings 'uninitialized'; # fix possible unimports
132 local *__tmp = *{ ${ "${cleanee}::" }{ $f } };
133 delete ${ "${cleanee}::" }{ $f };
137 # restore non-code slots to symbol
138 for my $t (qw( SCALAR ARRAY HASH IO FORMAT )) {
139 next SLOT unless defined *__tmp{ $t };
140 *{ "${cleanee}::$f" } = *__tmp{ $t };
144 $store->{handler_is_installed} = 1;
152 This method will be called when you do a
156 It will start a new section of code that defines functions to clean up.
163 # the calling class, the current functions and our storage
164 my $cleanee = caller;
165 my $functions = $pragma->get_functions($cleanee);
166 my $store = $pragma->get_class_store($cleanee);
168 # register all unknown previous functions as excluded
169 for my $f (keys %$functions) {
170 next if $store->{remove}{ $f }
171 or $store->{exclude}{ $f };
172 $store->{exclude}{ $f } = 1;
178 =head2 get_class_store
180 This returns a reference to a hash in a passed package containing
181 information about function names included and excluded from removal.
185 sub get_class_store {
186 my ($pragma, $class) = @_;
188 return \%{ "${class}::${STORAGE_VAR}" };
193 Takes a class as argument and returns all currently defined functions
194 in it as a hash reference with the function name as key and a typeglob
195 reference to the symbol as value.
200 my ($pragma, $class) = @_;
203 map { @$_ } # key => value
204 grep { *{ $_->[1] }{CODE} } # only functions
205 map { [$_, qualify_to_ref( $_, $class )] } # get globref
206 grep { $_ !~ /::$/ } # no packages
207 do { no strict 'refs'; keys %{ "${class}::" } } # symbol entries
211 =head1 IMPLEMENTATION DETAILS
213 This module works through the effect that a
215 delete $SomePackage::{foo};
217 will remove the C<foo> symbol from C<$SomePackage> for run time lookups
218 (e.g., method calls) but will leave the entry alive to be called by
219 already resolved names in the package itself. C<namespace::clean> will
220 restore and therefor in effect keep all glob slots that aren't C<CODE>.
222 A test file has been added to the perl core to ensure that this behaviour
223 will be stable in future releases.
225 Just for completeness sake, if you want to remove the symbol completely,
226 use C<undef> instead.
232 =head1 AUTHOR AND COPYRIGHT
234 Robert 'phaylon' Sedlacek C<E<lt>rs@474.atE<gt>>, with many thanks to
235 Matt S Trout for the inspiration on the whole idea.
239 This program is free software; you can redistribute it and/or modify
240 it under the same terms as perl itself.