Indomitus has asked for the wisdom of the Perl Monks concerning the following question:

What is the scope of a variable called with my in a signal handler anonymous subroutine? Right now I have this code: 
my $rip_done = 0;

$SIG{CHLD} = sub { $rip_done = 1;
                   while( waitpid(-1, WNOHANG) > 0) {}  };

[download]
elsewhere in the program... 
if($rip_done == 1)
{
  do some stuff
}

[download]
In the interest of having as few global variables as possible, can I initialize $rip_done inside the sub and still use it elsewhere in the program? I'm still trying to get away from using global variables for everything so I'm not 100% up to snuff on scope yet. I'm also new to signal handlers so if I'm not doing things right here, please let me know. Thanks a lot.

Replies are listed 'Best First'.
Re: Variable Scope in a Signal Handler?
by Fastolfe (Vicar) on Nov 01, 2001 at 22:02 UTC
    Yes, if you use a global variable or if your signal handler is a closure with a lexical in the scope you're after. Try this simple test and see if it prints out what you expect: 
    {
  my $var = 1;
  $SIG{HUP} = sub { print "HUP; \$var=$var\n"; $var++; };
}

print "in main program, \$var=$var\n";
kill('HUP', $$);
print "in main program, \$var=$var\n";
kill('HUP', $$);
print "in main program, \$var=$var\n";

    [download]
    Then try moving $var into the main program and declare it with 'use vars'.
[reply]
[d/l]
[select]

Back to Seekers of Perl Wisdom