For the specific question, a better option might be to use overload and do dispatch based on the value you get. Something like:
in reply to inheritance turns back and bites
'+' => 'add',
'-' => 'subtract',
fallback => 1;
my ($x, $y) = @_[0..1];
($x, $y) = ($y, $x) if $_;
? $x + $y
: $x . $y;
Now, personally, I would never overload + to act as string concatenation. Concatenation isn't commutative, which breaks the implicit contract most people have with addition. As well, how do you define multiplication for strings?
We are the carpenters and bricklayers of the Information Age.
Please remember that I'm crufty and crochety. All opinions are purely mine and all code is untested, unless otherwise specified.