sub do_eval {
    my $var = shift;

    if (eval {'foobar' =~ /$var/}) {
        print "foobar matched /$var/\n";
    }
    elsif (length $@) {
        print "ERROR: bad regex given to do_eval()\n";
    }
    else {
        print "foobar did not match /$var/\n";
    }
}

do_eval('foo(bar');
do_eval('foo/; print "ALL YOUR BASE ARE BELONG TO US!\n"; /bar');
do_eval('foo.*(bar)?');