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1 | package namespace::clean; |
2 | |
3 | =head1 NAME |
4 | |
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5 | namespace::clean - Keep imports and functions out of your namespace |
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6 | |
7 | =cut |
8 | |
9 | use warnings; |
10 | use strict; |
11 | |
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12 | use vars qw( $VERSION $STORAGE_VAR ); |
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13 | use Symbol qw( qualify_to_ref ); |
14 | use Filter::EOF; |
15 | |
16 | =head1 VERSION |
17 | |
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18 | 0.05 |
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19 | |
20 | =cut |
21 | |
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22 | $VERSION = 0.05; |
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23 | $STORAGE_VAR = '__NAMESPACE_CLEAN_STORAGE'; |
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24 | |
25 | =head1 SYNOPSIS |
26 | |
27 | package Foo; |
28 | use warnings; |
29 | use strict; |
30 | |
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31 | use Carp qw(croak); # 'croak' will be removed |
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32 | |
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33 | sub bar { 23 } # 'bar' will be removed |
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34 | |
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35 | # remove all previously defined functions |
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36 | use namespace::clean; |
37 | |
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38 | sub baz { bar() } # 'baz' still defined, 'bar' still bound |
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39 | |
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40 | # begin to collection function names from here again |
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41 | no namespace::clean; |
42 | |
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43 | sub quux { baz() } # 'quux' will be removed |
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44 | |
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45 | # remove all functions defined after the 'no' unimport |
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46 | use namespace::clean; |
47 | |
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48 | # Will print: 'No', 'No', 'Yes' and 'No' |
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49 | print +(__PACKAGE__->can('croak') ? 'Yes' : 'No'), "\n"; |
50 | print +(__PACKAGE__->can('bar') ? 'Yes' : 'No'), "\n"; |
51 | print +(__PACKAGE__->can('baz') ? 'Yes' : 'No'), "\n"; |
9b680ffe |
52 | print +(__PACKAGE__->can('quux') ? 'Yes' : 'No'), "\n"; |
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53 | |
54 | 1; |
55 | |
56 | =head1 DESCRIPTION |
57 | |
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 |
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61 | classes that are included via multiple inheritance by loading them as |
62 | base classes. |
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63 | |
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. |
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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. |
68 | |
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. |
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71 | |
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72 | You can use the C<-except> flag to tell C<namespace::clean> that you |
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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: |
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75 | |
76 | use ModuleExportingImport; |
77 | use namespace::clean -except => [qw( import )]; |
78 | |
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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. |
81 | |
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82 | =head1 METHODS |
83 | |
84 | You shouldn't need to call any of these. Just C<use> the package at the |
85 | appropriate place. |
86 | |
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87 | =cut |
88 | |
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89 | =head2 import |
90 | |
91 | Makes a snapshot of the current defined functions and registers a |
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92 | L<Filter::EOF> cleanup routine to remove those symbols at the end |
93 | of the compile-time. |
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94 | |
95 | =cut |
96 | |
97 | sub import { |
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98 | my ($pragma, %args) = @_; |
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99 | |
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100 | # calling class, all current functions and our storage |
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101 | my $cleanee = caller; |
102 | my $functions = $pragma->get_functions($cleanee); |
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103 | my $store = $pragma->get_class_store($cleanee); |
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104 | |
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105 | # except parameter can be array ref or single value |
106 | my %except = map {( $_ => 1 )} ( |
107 | $args{ -except } |
108 | ? ( ref $args{ -except } eq 'ARRAY' ? @{ $args{ -except } } : $args{ -except } ) |
109 | : () |
110 | ); |
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111 | |
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112 | # register symbols for removal, if they have a CODE entry |
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113 | for my $f (keys %$functions) { |
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114 | next if $except{ $f }; |
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115 | next unless $functions->{ $f } |
116 | and *{ $functions->{ $f } }{CODE}; |
117 | $store->{remove}{ $f } = 1; |
118 | } |
119 | |
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120 | # register EOF handler on first call to import |
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121 | unless ($store->{handler_is_installed}) { |
122 | Filter::EOF->on_eof_call(sub { |
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123 | SYMBOL: |
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124 | for my $f (keys %{ $store->{remove} }) { |
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125 | |
126 | # ignore already removed symbols |
127 | next SYMBOL if $store->{exclude}{ $f }; |
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128 | no strict 'refs'; |
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129 | |
130 | # keep original value to restore non-code slots |
131 | local *__tmp = *{ ${ "${cleanee}::" }{ $f } }; |
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132 | delete ${ "${cleanee}::" }{ $f }; |
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133 | |
134 | SLOT: |
135 | # restore non-code slots to symbol |
136 | for my $t (qw( SCALAR ARRAY HASH IO FORMAT )) { |
137 | next SLOT unless defined *__tmp{ $t }; |
138 | *{ "${cleanee}::$f" } = *__tmp{ $t }; |
139 | } |
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140 | } |
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141 | }); |
142 | $store->{handler_is_installed} = 1; |
143 | } |
144 | |
145 | return 1; |
146 | } |
147 | |
148 | =head2 unimport |
149 | |
150 | This method will be called when you do a |
151 | |
152 | no namespace::clean; |
153 | |
154 | It will start a new section of code that defines functions to clean up. |
155 | |
156 | =cut |
157 | |
158 | sub unimport { |
159 | my ($pragma) = @_; |
160 | |
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161 | # the calling class, the current functions and our storage |
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162 | my $cleanee = caller; |
163 | my $functions = $pragma->get_functions($cleanee); |
164 | my $store = $pragma->get_class_store($cleanee); |
165 | |
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166 | # register all unknown previous functions as excluded |
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167 | for my $f (keys %$functions) { |
168 | next if $store->{remove}{ $f } |
169 | or $store->{exclude}{ $f }; |
170 | $store->{exclude}{ $f } = 1; |
171 | } |
172 | |
173 | return 1; |
174 | } |
175 | |
176 | =head2 get_class_store |
177 | |
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178 | This returns a reference to a hash in a passed package containing |
179 | information about function names included and excluded from removal. |
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180 | |
181 | =cut |
182 | |
183 | sub get_class_store { |
184 | my ($pragma, $class) = @_; |
185 | no strict 'refs'; |
186 | return \%{ "${class}::${STORAGE_VAR}" }; |
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187 | } |
188 | |
189 | =head2 get_functions |
190 | |
191 | Takes a class as argument and returns all currently defined functions |
192 | in it as a hash reference with the function name as key and a typeglob |
193 | reference to the symbol as value. |
194 | |
195 | =cut |
196 | |
197 | sub get_functions { |
198 | my ($pragma, $class) = @_; |
199 | |
200 | return { |
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201 | map { @$_ } # key => value |
202 | grep { *{ $_->[1] }{CODE} } # only functions |
203 | map { [$_, qualify_to_ref( $_, $class )] } # get globref |
204 | grep { $_ !~ /::$/ } # no packages |
205 | do { no strict 'refs'; keys %{ "${class}::" } } # symbol entries |
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206 | }; |
207 | } |
208 | |
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209 | =head1 IMPLEMENTATION DETAILS |
210 | |
211 | This module works through the effect that a |
212 | |
213 | delete $SomePackage::{foo}; |
214 | |
215 | will remove the C<foo> symbol from C<$SomePackage> for run time lookups |
216 | (e.g., method calls) but will leave the entry alive to be called by |
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217 | already resolved names in the package itself. C<namespace::clean> will |
218 | restore and therefor in effect keep all glob slots that aren't C<CODE>. |
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219 | |
220 | A test file has been added to the perl core to ensure that this behaviour |
221 | will be stable in future releases. |
222 | |
223 | Just for completeness sake, if you want to remove the symbol completely, |
224 | use C<undef> instead. |
225 | |
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226 | =head1 SEE ALSO |
227 | |
228 | L<Filter::EOF> |
229 | |
230 | =head1 AUTHOR AND COPYRIGHT |
231 | |
232 | Robert 'phaylon' Sedlacek C<E<lt>rs@474.atE<gt>>, with many thanks to |
233 | Matt S Trout for the inspiration on the whole idea. |
234 | |
235 | =head1 LICENSE |
236 | |
237 | This program is free software; you can redistribute it and/or modify |
238 | it under the same terms as perl itself. |
239 | |
240 | =cut |
241 | |
242 | 1; |