[Python-Dev] Can Python guarantee the order of keyword-only parameters?

[Nick Coghlan]

On 28 November 2017 at 15:42, Larry Hastings <larry at hastings.org> wrote:
> On 11/27/2017 03:58 PM, Yury Selivanov wrote:
>> We can't say anything about the order if someone passes a partial
>> object
>
> Sure we could.  We could ensure that functools.partial behaves in a sane
> way, then document and guarantee that behavior.

Right, I think the main implication here would be that we need to
ensure that any signature manipulation operations *we* provide are
order preserving.

Fortunately for Larry, we kinda cheat on that front: all the logic for
dealing with this problem is in the inspect module itself, which knows
about all the different ways we manipulate signatures in the standard
library. That means that if we want to declare that the inspect module
will be order preserving, we can, and it shouldn't require changes to
anything else.

Cheers,
Nick.

P.S. Note that inspect.getfullargspec() was actually undeprecated a
while back - enough folks that didn't need access to the function
annotations were reimplementing it for themselves "because the
standard library API is deprecated" that the most logical course of
action was to just declare it as being supported again. I don't think
that changes the argument here though - it just means guaranteed order
preservation in that API will only happen if we declare dicts to be
insertion ordered in general.

-- 
Nick Coghlan   |   ncoghlan at gmail.com   |   Brisbane, Australia