Stricter types

[CharString]

Refactors:

• looping over Member descriptors
• calculate String length_encoding with a logarithm instead of a loop.

Makes things like this give a type error:

class NullTest(tlv.TLVStructure):
    n = tlv.BoolMember(None, nullable=True)
    notn = tlv.BoolMember(None, nullable=False)

s = NullTest()
s.n = None  # checks ok
s.notn = None  # doesn't type check

Doesn't handle StructMember yet.

[CharString]

PS this typechecks in pyright, doesn't with mypy and I haven't checked pyre

[tannewt]

Very cool! Thank you! I hadn't seen typing + descriptors before.

[CharString]

Very cool! Thank you! I hadn't seen typing + descriptors before.

@tannewt I haven't seen it done either. It was a bit of a puzzle. Annotating __new__ and returning Self[Optional[_T]] in case of optional ∨ nullable was a dead end.