Scope::Guard(3) User Contributed Perl Documentation Scope::Guard(3)
NAME
Scope::Guard - lexically-scoped resource management
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 immediately
(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
0.21
SEE ALSO
o B::Hooks::EndOfScope(3)
o End(3)
o Guard(3)
o Hook::Scope(3)
o Object::Destroyer(3)
o Perl::AtEndOfScope(3)
o ReleaseAction(3)
o Scope::local_OnExit(3)
o Scope::OnExit(3)
o Sub::ScopeFinalizer(3)
o Value::Canary(3)
AUTHOR
chocolateboy <chocolate@cpan.org>
COPYRIGHT
Copyright (c) 2005-2015, chocolateboy.
This module is free software. It may be used, redistributed and/or
modified under the same terms as Perl itself.
perl v5.30.0 2015-07-19 Scope::Guard(3)
scope-guard 0.210.0 - Generated Wed Jul 22 09:46:56 CDT 2020