#!/usr/bin/perl
$a1 = '(?<a>\d)';
$a2 = $a1;
#$a2 = '(?<b>\d)';
$b = '\d';
$rx = qr/(?:${a}${b}|${a2}:${b})/;
#$string = "12";
$string = "1:2";
while (1) {
$string =~ $rx;
$tmp = $+{a};
}
#!/usr/bin/perl
$a1 = '(?<a>\d)';
$a2 = $a1;
#$a2 = '(?<b>\d)';
$b = '\d';
$rx = qr/(?:${a}${b}|${a2}:${b})/;
#$string = "12";
$string = "1:2";
while (1) {
$string =~ $rx;
$tmp = $+{a};
}