On 2015年08月28日 18:35 +0200, Parke wrote:
IMHO 4 meters is not the number 4 with additional information, it should have its own "meters" type. So if you want the 4 to be different from other fours (e.g. not allowing addition with them), wrap in in a table or a userdata object and give it the arithmetic metamethods along with an appropriate __tostring. If that is too expensive performance-wise, then I still think that rather than allowing per-value metatables for all value types, a new value type should be introduced for this purpose (or a way to create new value-(sub)types on the fly?). The fact that all 4s are the same is IMHO not (only) a limitation, it also reliefs us from much complexity. (Sorry if that has all already been said, I haven't read all the messages about this topic.)As far as numbers with different metatables... that might allow units of measure (or other type information) to be associated with numbers. I have used that capability in other languages in pursuit of correctness and more informative error messages. For example, is 4 meters the same as 4 feet? 4 US dollars the same as 4 Euros?
‒ Christian