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Scope::Guard.3pm
Langue: en
Version: 2010-03-26 (fedora - 01/12/10)
Section: 3 (Bibliothèques de fonctions)
Sommaire
NAME
Scope::Guard - lexically-scoped resource managementSYNOPSIS
my $guard = guard { ... }; # or my $guard = scope_guard \&handler; # or my $guard = Scope::Guard->new(\&handler); $guard->dismiss(); # disable the handler
DESCRIPTION
This module provides a convenient way to perform cleanup or other forms of resource management at the end of a scope. It is particularly useful when dealing with exceptions: the "Scope::Guard" constructor takes a reference to a subroutine that is guaranteed to be called even if the thread of execution is aborted prematurely. This effectively allows lexically-scoped ``promises'' to be made that are automatically honoured by perl's garbage collector.For more information, see: <http://www.drdobbs.com/cpp/184403758>
METHODS
new
my $guard = Scope::Guard->new(sub { ... }); # or my $guard = Scope::Guard->new(\&handler);
The "new" method creates a new "Scope::Guard" object which calls the supplied handler when its "DESTROY" method is called, typically at the end of the scope.
dismiss
$guard->dismiss(); # or $guard->dismiss(1);
"dismiss" detaches the handler from the "Scope::Guard" object. This revokes the ``promise'' to call the handler when the object is destroyed.
The handler can be re-enabled by calling:
$guard->dismiss(0);
EXPORTS
guard
"guard" takes a block and returns a new "Scope::Guard" object. It can be used as a shorthand for:Scope::Guard->new(...)
e.g.
my $guard = guard { ... };
- or it can be called in void context to create a guard for the current scope e.g.
guard { ... };
Because there is no way to dismiss the guard in the latter case, it is assumed that the block knows how to deal with situations in which the resource has already been managed e.g.
guard { if ($resource->locked) { $resource->unlock; } };
scope_guard
"scope_guard" is the same as "guard", but it takes a code ref rather than a block. e.g.my $guard = scope_guard \&handler;
or:
my $guard = scope_guard sub { ... };
or:
my $guard = scope_guard $handler;
Like "guard", it can be called in void context to install an anonymous guard in the current scope.
VERSION
0.12SEE ALSO
- *
- B::Hooks::EndOfScope
- *
- End
- *
- Guard
- *
- Hook::Scope
- *
- Object::Destroyer
- *
- Perl::AtEndOfScope
- *
- ReleaseAction
- *
- Scope::OnExit
- *
- Sub::ScopeFinalizer
- *
- Value::Canary
AUTHOR
chocolateboy <chocolate@cpan.org>COPYRIGHT
Copyright (c) 2005-2010, chocolateboy.This module is free software. It may be used, redistributed and/or modified under the same terms as Perl itself.
Contenus ©2006-2024 Benjamin Poulain
Design ©2006-2024 Maxime Vantorre