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16.16. Temporarily Overriding a Signal Handler
16.16.1. Problem
You
want to install a signal handler only for a particular subroutine.
For instance, your subroutine catches SIGINT, and
you don't want to disturb SIGINT handling outside
the subroutine.
16.16.2. Solution
Use local to
temporarily override a signal's behavior:# the signal handler
sub ding {
$SIG{INT} = \&ding;
warn "\aEnter your name!\n";
}
# prompt for name, overriding SIGINT
sub get_name {
local $SIG{INT} = \&ding;
my $name;
print "Kindly Stranger, please enter your name: ";
chomp( $name = <> );
return $name;
}
16.16.3. Discussion
You must use local rather than
my to save away one value out of
%SIG. The change remains in effect throughout the
execution of that block, including in anything called from it. In
this case, that's the get_name subroutine. If the
signal is delivered while another function that your function calls
is running, your signal handler is triggered—unless the called
subroutine installs its own signal handler. The previous value of the
hash is automatically restored when the block exits. This is one of
the (few) places where dynamic scoping is more convenient than
confusing.
16.16.4. See Also
Recipe 10.13; Recipe 16.15; Recipe 16.18
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| 16.15. Installing a Signal Handler |  | 16.17. Writing a Signal Handler |
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