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Comparing Guard/Guard.pm (file contents):
Revision 1.7 by root, Sat Dec 13 18:44:16 2008 UTC vs.
Revision 1.8 by root, Sat Dec 13 18:47:40 2008 UTC

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52=item scope_guard BLOCK 52=item scope_guard BLOCK
53 53
54Registers a block that is executed when the current scope (block, 54Registers a block that is executed when the current scope (block,
55function, method, eval etc.) is exited. 55function, method, eval etc.) is exited.
56 56
57See the EXCEPTIONS section for an explanation of how exceptions
58(i.e. C<die>) are handled inside guard blocks.
59
57The description below sounds a bit complicated, but that's just because 60The description below sounds a bit complicated, but that's just because
58C<scope_guard> tries to get even corner cases "right": the goal is to 61C<scope_guard> tries to get even corner cases "right": the goal is to
59provide you with a rock solid clean up tool. 62provide you with a rock solid clean up tool.
60 63
61This is similar to this code fragment: 64The behaviour is similar to this code fragment:
62 65
63 eval ... code following scope_guard ... 66 eval ... code following scope_guard ...
64 { 67 {
65 local $@; 68 local $@;
66 eval BLOCK; 69 eval BLOCK;
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70 73
71Except it is much faster, and the whole thing gets executed even when the 74Except it is much faster, and the whole thing gets executed even when the
72BLOCK calls C<exit>, C<goto>, C<last> or escapes via other means. 75BLOCK calls C<exit>, C<goto>, C<last> or escapes via other means.
73 76
74If multiple BLOCKs are registered to the same scope, they will be executed 77If multiple BLOCKs are registered to the same scope, they will be executed
75in reverse order. Stuff like C<local> is managed via the same mechanism, 78in reverse order. Other scope-related things such as C<local> are managed
76so variables C<local>ised after calling C<scope_guard> will be restored 79via the same mechanism, so variables C<local>ised I<after> calling
77when the guard runs. 80C<scope_guard> will be restored when the guard runs.
78
79See B<EXCEPTIONS>, below, for an explanation of exception handling
80(C<die>) within guard blocks.
81 81
82Example: temporarily change the timezone for the current process, 82Example: temporarily change the timezone for the current process,
83ensuring it will be reset when the C<if> scope is exited: 83ensuring it will be reset when the C<if> scope is exited:
84 84
85 use Guard; 85 use Guard;
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103when the BLOCK gets executed: when the last reference to the object gets 103when the BLOCK gets executed: when the last reference to the object gets
104destroyed, the BLOCK gets executed as with C<scope_guard>. 104destroyed, the BLOCK gets executed as with C<scope_guard>.
105 105
106The returned object can be copied as many times as you want. 106The returned object can be copied as many times as you want.
107 107
108See B<EXCEPTIONS>, below, for an explanation of exception handling 108See the EXCEPTIONS section for an explanation of how exceptions
109(C<die>) within guard blocks. 109(i.e. C<die>) are handled inside guard blocks.
110 110
111Example: acquire a Coro::Semaphore for a second by registering a 111Example: acquire a Coro::Semaphore for a second by registering a
112timer. The timer callback references the guard used to unlock it again. 112timer. The timer callback references the guard used to unlock it again.
113 113
114 use AnyEvent; 114 use AnyEvent;

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