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10 | # to go back to "/" no matter how myfun exits: |
10 | # to go back to "/" no matter how myfun exits: |
11 | sub myfun { |
11 | sub myfun { |
12 | scope_guard { chdir "/" }; |
12 | scope_guard { chdir "/" }; |
13 | chdir "/etc"; |
13 | chdir "/etc"; |
14 | |
14 | |
15 | call_function_that_might_die_or_other_fun_stuff; |
15 | code_that_might_die_or_does_other_fun_stuff; |
16 | } |
16 | } |
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17 | |
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18 | # create an object that, when the last reference to it is gone, |
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19 | # invokes the given codeblock: |
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20 | my $guard = guard { print "destroyed!\n" }; |
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21 | undef $guard; # probably destroyed here |
17 | |
22 | |
18 | =head1 DESCRIPTION |
23 | =head1 DESCRIPTION |
19 | |
24 | |
20 | This module implements so-called "guards". A guard is something (usually |
25 | This module implements so-called "guards". A guard is something (usually |
21 | an object) that "guards" a resource, ensuring that it is cleaned up when |
26 | an object) that "guards" a resource, ensuring that it is cleaned up when |
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37 | package Guard; |
42 | package Guard; |
38 | |
43 | |
39 | no warnings; |
44 | no warnings; |
40 | |
45 | |
41 | BEGIN { |
46 | BEGIN { |
42 | $VERSION = '0.5'; |
47 | $VERSION = '1.021'; |
43 | @ISA = qw(Exporter); |
48 | @ISA = qw(Exporter); |
44 | @EXPORT = qw(guard scope_guard); |
49 | @EXPORT = qw(guard scope_guard); |
45 | |
50 | |
46 | require Exporter; |
51 | require Exporter; |
47 | |
52 | |
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189 | =head1 THANKS |
194 | =head1 THANKS |
190 | |
195 | |
191 | Thanks to Marco Maisenhelder, who reminded me of the C<$Guard::DIED> |
196 | Thanks to Marco Maisenhelder, who reminded me of the C<$Guard::DIED> |
192 | solution to the problem of exceptions. |
197 | solution to the problem of exceptions. |
193 | |
198 | |
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199 | =head1 SEE ALSO |
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200 | |
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201 | L<Scope::Guard> and L<Sub::ScopeFinalizer>, which actually implement |
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202 | dynamic, not scoped guards, and have a lot higher CPU, memory and typing |
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203 | overhead. |
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204 | |
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205 | L<Hook::Scope>, which has apparently never been finished and corrupts |
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206 | memory when used. |
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207 | |
194 | =cut |
208 | =cut |
195 | |
209 | |