$text = "abc123def";
$text_match = qr/(\D+)(\d+)(?{ dumpr() })(\D+)/;
$text =~ $text_match;

use Devel::Peek;
sub dumpr {
    Dump($+), Dump($1), Dump($2), Dump($3);
    local $\ = "\n";
    print $+;
    print $1;
    print $2;
    print $3;
}