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 Explicitely removing functions when your scope is compiled
67 It is also possible to explicitely tell "namespace::clean" what
68 packages to remove when the surrounding scope has finished compiling.
69 Here is an example:
70 package Foo;
72 use strict;
73 # blessed NOT available
75 sub my_class {
77 use Scalar::Util qw( blessed );
78 use namespace::clean qw( blessed );
79 # blessed available
81 return blessed shift;
82 }
83 # blessed NOT available
85 Moose
87 When using "namespace::clean" together with Moose you want to keep the
88 installed "meta" method. So your classes should look like:
89 package Foo;
91 use Moose;
92 use namespace::clean -except => 'meta';
93 ...
94 Same goes for Moose::Role.
96 Cleaning other packages
98 You can tell "namespace::clean" that you want to clean up another
99 package instead of the one importing. To do this you have to pass in
100 the "-cleanee" option like this:
101 package My::MooseX::namespace::clean;
103 use strict;
104 use namespace::clean (); # no cleanup, just load
106 sub import {
108 namespace::clean->import(
109 -cleanee => scalar(caller),
110 -except => 'meta',
111 );
112 }
113 If you don't care about "namespace::clean"s discover-and-"-except"
115 logic, and just want to remove subroutines, try "clean_subroutines".
116
118 clean_subroutines
119 This exposes the actual subroutine-removal logic.
120 namespace::clean->clean_subroutines($cleanee, qw( subA subB ));
122 will remove "subA" and "subB" from $cleanee. Note that this will remove
124 the subroutines immediately and not wait for scope end. If you want to
125 have this effect at a specific time (e.g. "namespace::clean" acts on
126 scope compile end) it is your responsibility to make sure it runs at
127 that time.
128 import
130 Makes a snapshot of the current defined functions and installs a
131 B::Hooks::EndOfScope hook in the current scope to invoke the cleanups.
132 unimport
134 This method will be called when you do a
135 no namespace::clean;
137 It will start a new section of code that defines functions to clean up.
139 get_class_store
141 This returns a reference to a hash in a passed package containing
142 information about function names included and excluded from removal.
143 get_functions
145 Takes a class as argument and returns all currently defined functions
146 in it as a hash reference with the function name as key and a typeglob
147 reference to the symbol as value.
148
150 This module works through the effect that a
151 delete $SomePackage::{foo};
153 will remove the "foo" symbol from $SomePackage for run time lookups
155 (e.g., method calls) but will leave the entry alive to be called by
156 already resolved names in the package itself. "namespace::clean" will
157 restore and therefor in effect keep all glob slots that aren't "CODE".
158 A test file has been added to the perl core to ensure that this
160 behaviour will be stable in future releases.
161 Just for completeness sake, if you want to remove the symbol
163 completely, use "undef" instead.
164
166 B::Hooks::EndOfScope
167
169 Many thanks to Matt S Trout for the inspiration on the whole idea.
170
172 · Robert 'phaylon' Sedlacek <rs@474.at>
173 · Florian Ragwitz <rafl@debian.org>
175 · Jesse Luehrs <doy@tozt.net>
177
179 This software is copyright (c) 2010 by Robert 'phaylon' Sedlacek.
180 This is free software; you can redistribute it and/or modify it under
182 the same terms as the Perl 5 programming language system itself.
183perl v5.12.1 2010-06-13 namespace::clean(3)