[Python-Dev] PEP 457: Syntax For Positional-Only Parameters

[Paul Moore]

On 9 October 2013 10:46, Nick Coghlan <ncoghlan at gmail.com> wrote:
> The PEP needs to state more clearly up front (preferably in the title) that
> it's about *reserving* a Python level syntax that matches the syntax we
> worked out for Argument Clinic at PyCon US. Explicitly stating that the
> requirements that drive the Argument Clinic design are to support the
> signature of all current CPython builtins and extension modules would also
> be helpful.
>
> Generally, it needs to be a bit clearer that the intent of the PEP isn't to
> say "let's do this", it's to be explicit that acceptance of the Argument
> Clinic PEP severely constrains the design space for possible solutions if we
> ever *did* implement Python level support for positional only arguments.

I'm confused about the expectations here. To be specific, I hate the
syntax, I find the proliferation of punctuation messy and unhelpful.
But if it's only for documentation/internal use, I don't really mind -
I can see that we need some way to express this stuff, and TBH I don't
care enough to make a fuss either way.

But if the intention is that any attempt to add the functionality to
Python will be constrained to use the syntax here, surely that means
we need to have all of the usability arguments and bikeshedding *now*.
otherwise the opportunity is lost?

Personally, I'm -1 on the idea that this acts as any sort of precedent
or design constraint for a Python-level implementation of the
functionality, and -0 on it as a syntax for Argument Clinic, and as a
documentation convention. And either way, I agree with Nick that the
PEP needs to be very clear about its scope and impact.

Paul