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Man Pages


Manual Reference Pages  -  SCOPE::GUARD (3)

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NAME

Scope::Guard - lexically-scoped resource management

CONTENTS

SYNOPSIS



    my $guard = guard { ... };

      # or

    my $guard = scope_guard \&handler;

      # or

    my $guard = Scope::Guard->new(sub { ... });

    $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 { ... };



Note: calling guard anonymously, i.e. in void context, will raise an exception. This is because anonymous guards are destroyed <B>immediatelyB> (rather than at the end of the scope), which is unlikely to be the desired behaviour.

    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;



As with guard, calling scope_guard in void context will raise an exception.

VERSION

0.20

SEE ALSO

o B::Hooks::EndOfScope
o End
o Guard
o Hook::Scope
o Object::Destroyer
o Perl::AtEndOfScope
o ReleaseAction
o Scope::local_OnExit
o Scope::OnExit
o Sub::ScopeFinalizer
o 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.

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perl v5.20.3 SCOPE::GUARD (3) 2010-05-16

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