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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 | 0.03 |
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19 | |
20 | =cut |
21 | |
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22 | $VERSION = 0.03; |
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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"; |
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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 | |
72 | =head1 METHODS |
73 | |
74 | You shouldn't need to call any of these. Just C<use> the package at the |
75 | appropriate place. |
76 | |
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77 | =cut |
78 | |
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79 | =head2 import |
80 | |
81 | Makes a snapshot of the current defined functions and registers a |
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82 | L<Filter::EOF> cleanup routine to remove those symbols at the end |
83 | of the compile-time. |
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84 | |
85 | =cut |
86 | |
87 | sub import { |
88 | my ($pragma) = @_; |
89 | |
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90 | # calling class, all current functions and our storage |
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91 | my $cleanee = caller; |
92 | my $functions = $pragma->get_functions($cleanee); |
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93 | my $store = $pragma->get_class_store($cleanee); |
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94 | |
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95 | # register symbols for removal, if they have a CODE entry |
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96 | for my $f (keys %$functions) { |
97 | next unless $functions->{ $f } |
98 | and *{ $functions->{ $f } }{CODE}; |
99 | $store->{remove}{ $f } = 1; |
100 | } |
101 | |
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102 | # register EOF handler on first call to import |
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103 | unless ($store->{handler_is_installed}) { |
104 | Filter::EOF->on_eof_call(sub { |
105 | for my $f (keys %{ $store->{remove} }) { |
106 | next if $store->{exclude}{ $f }; |
107 | no strict 'refs'; |
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108 | delete ${ "${cleanee}::" }{ $f }; |
109 | } |
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110 | }); |
111 | $store->{handler_is_installed} = 1; |
112 | } |
113 | |
114 | return 1; |
115 | } |
116 | |
117 | =head2 unimport |
118 | |
119 | This method will be called when you do a |
120 | |
121 | no namespace::clean; |
122 | |
123 | It will start a new section of code that defines functions to clean up. |
124 | |
125 | =cut |
126 | |
127 | sub unimport { |
128 | my ($pragma) = @_; |
129 | |
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130 | # the calling class, the current functions and our storage |
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131 | my $cleanee = caller; |
132 | my $functions = $pragma->get_functions($cleanee); |
133 | my $store = $pragma->get_class_store($cleanee); |
134 | |
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135 | # register all unknown previous functions as excluded |
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136 | for my $f (keys %$functions) { |
137 | next if $store->{remove}{ $f } |
138 | or $store->{exclude}{ $f }; |
139 | $store->{exclude}{ $f } = 1; |
140 | } |
141 | |
142 | return 1; |
143 | } |
144 | |
145 | =head2 get_class_store |
146 | |
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147 | This returns a reference to a hash in a passed package containing |
148 | information about function names included and excluded from removal. |
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149 | |
150 | =cut |
151 | |
152 | sub get_class_store { |
153 | my ($pragma, $class) = @_; |
154 | no strict 'refs'; |
155 | return \%{ "${class}::${STORAGE_VAR}" }; |
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156 | } |
157 | |
158 | =head2 get_functions |
159 | |
160 | Takes a class as argument and returns all currently defined functions |
161 | in it as a hash reference with the function name as key and a typeglob |
162 | reference to the symbol as value. |
163 | |
164 | =cut |
165 | |
166 | sub get_functions { |
167 | my ($pragma, $class) = @_; |
168 | |
169 | return { |
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170 | map { @$_ } # key => value |
171 | grep { *{ $_->[1] }{CODE} } # only functions |
172 | map { [$_, qualify_to_ref( $_, $class )] } # get globref |
173 | grep { $_ !~ /::$/ } # no packages |
174 | do { no strict 'refs'; keys %{ "${class}::" } } # symbol entries |
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175 | }; |
176 | } |
177 | |
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178 | =head1 IMPLEMENTATION DETAILS |
179 | |
180 | This module works through the effect that a |
181 | |
182 | delete $SomePackage::{foo}; |
183 | |
184 | will remove the C<foo> symbol from C<$SomePackage> for run time lookups |
185 | (e.g., method calls) but will leave the entry alive to be called by |
186 | already resolved names in the package itself. |
187 | |
188 | A test file has been added to the perl core to ensure that this behaviour |
189 | will be stable in future releases. |
190 | |
191 | Just for completeness sake, if you want to remove the symbol completely, |
192 | use C<undef> instead. |
193 | |
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194 | =head1 SEE ALSO |
195 | |
196 | L<Filter::EOF> |
197 | |
198 | =head1 AUTHOR AND COPYRIGHT |
199 | |
200 | Robert 'phaylon' Sedlacek C<E<lt>rs@474.atE<gt>>, with many thanks to |
201 | Matt S Trout for the inspiration on the whole idea. |
202 | |
203 | =head1 LICENSE |
204 | |
205 | This program is free software; you can redistribute it and/or modify |
206 | it under the same terms as perl itself. |
207 | |
208 | =cut |
209 | |
210 | 1; |