On 07/26/2017 09:05 AM, Nick Coghlan wrote:
On 26 July 2017 at 11:05, Steven D'Aprano <steve@pearwood.info> wrote:
I don't see any way that this proposal can be anything by a subtle source of bugs. We have two *incompatible* requirements:
- we want to define the order of the fields according to the order we give keyword arguments;
- we want to give keyword arguments in any order without caring about the field order.
We can't have both, and we can't give up either without being a surprising source of annoyance and bugs.
I think the second stated requirement isn't a genuine requirement, as that *isn't* a general expectation.
I have to agree with D'Aprano on this one. I certainly do not *expect* keyword argument position to matter, and it seems to me the primary reason to make it matter was not for dicts, but because a class name space is implemented by dicts. Tuples, named or otherwise, are positional first -- order matters. Specifying point = ntuple(y=2, x=-3) and having point[0] == 3 is going to be bizarre. This will be a source for horrible bugs. -- ~Ethan~