1namespace::clean(3) User Contributed Perl Documentation namespace::clean(3)
2
6 namespace::clean - Keep imports and functions out of your namespace
7
9 package Foo;
10 use warnings;
11 use strict;
12 use Carp qw(croak); # 'croak' will be removed
14 sub bar { 23 } # 'bar' will be removed
16 # remove all previously defined functions
18 use namespace::clean;
19 sub baz { bar() } # 'baz' still defined, 'bar' still bound
21 # begin to collection function names from here again
23 no namespace::clean;
24 sub quux { baz() } # 'quux' will be removed
26 # remove all functions defined after the 'no' unimport
28 use namespace::clean;
29 # Will print: 'No', 'No', 'Yes' and 'No'
31 print +(__PACKAGE__->can('croak') ? 'Yes' : 'No'), "\n";
32 print +(__PACKAGE__->can('bar') ? 'Yes' : 'No'), "\n";
33 print +(__PACKAGE__->can('baz') ? 'Yes' : 'No'), "\n";
34 print +(__PACKAGE__->can('quux') ? 'Yes' : 'No'), "\n";
35 1;
37
39 Keeping packages clean
40 When you define a function, or import one, into a Perl package, it will
41 naturally also be available as a method. This does not per se cause
42 problems, but it can complicate subclassing and, for example, plugin
43 classes that are included via multiple inheritance by loading them as
44 base classes.
45 The "namespace::clean" pragma will remove all previously declared or
47 imported symbols at the end of the current package's compile cycle.
48 Functions called in the package itself will still be bound by their
49 name, but they won't show up as methods on your class or instances.
50 By unimporting via "no" you can tell "namespace::clean" to start
52 collecting functions for the next "use namespace::clean;"
53 specification.
54 You can use the "-except" flag to tell "namespace::clean" that you
56 don't want it to remove a certain function or method. A common use
57 would be a module exporting an "import" method along with some
58 functions:
59 use ModuleExportingImport;
61 use namespace::clean -except => [qw( import )];
62 If you just want to "-except" a single sub, you can pass it directly.
64 For more than one value you have to use an array reference.
65 Late binding caveat
67 Note that the technique used by this module relies on perl having
69 resolved all names to actual code references during the compilation of
70 a scope. While this is almost always what the interpreter does, there
71 are some exceptions, notably the sort SUBNAME style of the "sort"
72 built-in invocation. The following example will not work, because
73 "sort" does not try to resolve the function name to an actual code
74 reference until runtime.
75 use MyApp::Utils 'my_sorter';
77 use namespace::clean;
78 my @sorted = sort my_sorter @list;
80 You need to work around this by forcing a compile-time resolution like
82 so:
83 use MyApp::Utils 'my_sorter';
85 use namespace::clean;
86 my $my_sorter_cref = \&my_sorter;
88 my @sorted = sort $my_sorter_cref @list;
90 Explicitly removing functions when your scope is compiled
92 It is also possible to explicitly tell "namespace::clean" what packages
93 to remove when the surrounding scope has finished compiling. Here is an
94 example:
95 package Foo;
97 use strict;
98 # blessed NOT available
100 sub my_class {
102 use Scalar::Util qw( blessed );
103 use namespace::clean qw( blessed );
104 # blessed available
106 return blessed shift;
107 }
108 # blessed NOT available
110 Moose
112 When using "namespace::clean" together with Moose you want to keep the
113 installed "meta" method. So your classes should look like:
114 package Foo;
116 use Moose;
117 use namespace::clean -except => 'meta';
118 ...
119 Same goes for Moose::Role.
121 Cleaning other packages
123 You can tell "namespace::clean" that you want to clean up another
124 package instead of the one importing. To do this you have to pass in
125 the "-cleanee" option like this:
126 package My::MooseX::namespace::clean;
128 use strict;
129 use namespace::clean (); # no cleanup, just load
131 sub import {
133 namespace::clean->import(
134 -cleanee => scalar(caller),
135 -except => 'meta',
136 );
137 }
138 If you don't care about "namespace::clean"s discover-and-"-except"
140 logic, and just want to remove subroutines, try "clean_subroutines".
141
143 clean_subroutines
144 This exposes the actual subroutine-removal logic.
145 namespace::clean->clean_subroutines($cleanee, qw( subA subB ));
147 will remove "subA" and "subB" from $cleanee. Note that this will remove
149 the subroutines immediately and not wait for scope end. If you want to
150 have this effect at a specific time (e.g. "namespace::clean" acts on
151 scope compile end) it is your responsibility to make sure it runs at
152 that time.
153 import
155 Makes a snapshot of the current defined functions and installs a
156 B::Hooks::EndOfScope hook in the current scope to invoke the cleanups.
157 unimport
159 This method will be called when you do a
160 no namespace::clean;
162 It will start a new section of code that defines functions to clean up.
164 get_class_store
166 This returns a reference to a hash in a passed package containing
167 information about function names included and excluded from removal.
168 get_functions
170 Takes a class as argument and returns all currently defined functions
171 in it as a hash reference with the function name as key and a typeglob
172 reference to the symbol as value.
173
175 This module works through the effect that a
176 delete $SomePackage::{foo};
178 will remove the "foo" symbol from $SomePackage for run time lookups
180 (e.g., method calls) but will leave the entry alive to be called by
181 already resolved names in the package itself. "namespace::clean" will
182 restore and therefor in effect keep all glob slots that aren't "CODE".
183 A test file has been added to the perl core to ensure that this
185 behaviour will be stable in future releases.
186 Just for completeness sake, if you want to remove the symbol
188 completely, use "undef" instead.
189
191 B::Hooks::EndOfScope
192
194 Many thanks to Matt S Trout for the inspiration on the whole idea.
195
197 · Robert 'phaylon' Sedlacek <rs@474.at>
198 · Florian Ragwitz <rafl@debian.org>
200 · Jesse Luehrs <doy@tozt.net>
202 · Peter Rabbitson <ribasushi@cpan.org>
204 · Father Chrysostomos <sprout@cpan.org>
206
208 This software is copyright (c) 2011 by "AUTHORS"
209 This is free software; you can redistribute it and/or modify it under
211 the same terms as the Perl 5 programming language system itself.
212perl v5.30.1 2020-01-30 namespace::clean(3)