Should zero-length tuple types be a valid type? about eth-abi

[chriseth]

Python has zero-length tuples, too. I guess that would be the canonical corresponding value. The encoding is the empty byte string.

[davesque]

I suppose another approach would be to require that the only value in Python which could be encoded to a unit type would be None and it would encode to b'\x00' padded to 256 bits. Also, the only binary value which could be decoded as a unit type to the Python value None would be the same padded b'\x00' value. I think this way is more aligned with the mathematical definition of a unit type.

And yet another approach could involve using b'' (0 bytes) as the binary value to and from which the Python None would be encoded/decoded.

[davesque]

I suppose I figured that, if a 0-tuple is intended to represent a "unit" value, then None is actually the best semantic (and most memory efficient) equivalent in Python. Either way works for me though.

[davesque]

Oh. Never mind about the memory thing. CPython is apparently smart and only ever stores one instance of the 0-tuple in memory. Honestly, if that's the case, I don't really care about the semantic business as much.