I find this line really interesting. If I'm reading it right, you can alter the metatable (operator overloading) on the fly? So you could pass in a table as a parameter, set a metatable, play with some operators, then set a different metatable to overload operators differently?
In Python, the operators are kind of tied to specific classes. I guess you can go about casting and converting and inheriting and monkeypatching and such, but I don't think it's as straightforward as just setting a new metatable. Admittedly, I can't think of when I've ever needed to alter operator-overloading dynamically like that, so I've never really tried. Do you know if it's useful in Lua code? Or am I completely off-base here?
Hmm, the only times I've used it as where I'd be casting objects in other languages... I've used it to 'cast' between 'tables' doing similar things. like `my1.rect` to `my2.rect`, if they both use .x, .y, .width and .height to store their coordinates. (Not sure that's a good practice because they can change.) Yes, you can alter metatables any time, but I don't do it that often.