1Scope::Guard(3)       User Contributed Perl Documentation      Scope::Guard(3)
2
3
4

NAME

6       Scope::Guard - lexically-scoped resource management
7

SYNOPSIS

9           my $guard = guard { ... };
10
11             # or
12
13           my $guard = scope_guard \&handler;
14
15             # or
16
17           my $guard = Scope::Guard->new(sub { ... });
18
19           $guard->dismiss(); # disable the handler
20

DESCRIPTION

22       This module provides a convenient way to perform cleanup or other forms
23       of resource management at the end of a scope. It is particularly useful
24       when dealing with exceptions: the "Scope::Guard" constructor takes a
25       reference to a subroutine that is guaranteed to be called even if the
26       thread of execution is aborted prematurely. This effectively allows
27       lexically-scoped "promises" to be made that are automatically honoured
28       by perl's garbage collector.
29
30       For more information, see: <http://www.drdobbs.com/cpp/184403758>
31

METHODS

33   new
34           my $guard = Scope::Guard->new(sub { ... });
35
36             # or
37
38           my $guard = Scope::Guard->new(\&handler);
39
40       The "new" method creates a new "Scope::Guard" object which calls the
41       supplied handler when its "DESTROY" method is called, typically at the
42       end of the scope.
43
44   dismiss
45           $guard->dismiss();
46
47             # or
48
49           $guard->dismiss(1);
50
51       "dismiss" detaches the handler from the "Scope::Guard" object. This
52       revokes the "promise" to call the handler when the object is destroyed.
53
54       The handler can be re-enabled by calling:
55
56           $guard->dismiss(0);
57

EXPORTS

59   guard
60       "guard" takes a block and returns a new "Scope::Guard" object. It can
61       be used as a shorthand for:
62
63           Scope::Guard->new(...)
64
65       e.g.
66
67           my $guard = guard { ... };
68
69       Note: calling "guard" anonymously, i.e. in void context, will raise an
70       exception.  This is because anonymous guards are destroyed immediately
71       (rather than at the end of the scope), which is unlikely to be the
72       desired behaviour.
73
74   scope_guard
75       "scope_guard" is the same as "guard", but it takes a code ref rather
76       than a block.  e.g.
77
78           my $guard = scope_guard \&handler;
79
80       or:
81
82           my $guard = scope_guard sub { ... };
83
84       or:
85
86           my $guard = scope_guard $handler;
87
88       As with "guard", calling "scope_guard" in void context will raise an
89       exception.
90

VERSION

92       0.21
93

SEE ALSO

95       •   B::Hooks::EndOfScope
96
97       •   End
98
99       •   Guard
100
101       •   Hook::Scope
102
103       •   Object::Destroyer
104
105       •   Perl::AtEndOfScope
106
107       •   ReleaseAction
108
109       •   Scope::local_OnExit
110
111       •   Scope::OnExit
112
113       •   Sub::ScopeFinalizer
114
115       •   Value::Canary
116

AUTHOR

118       chocolateboy <chocolate@cpan.org>
119

121       Copyright (c) 2005-2015, chocolateboy.
122
123       This module is free software. It may be used, redistributed and/or
124       modified under the same terms as Perl itself.
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128perl v5.34.0                      2021-07-22                   Scope::Guard(3)
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