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

[Terry Reedy]

On 10/8/2013 9:31 PM, Benjamin Peterson wrote:
> 2013/10/8 Larry Hastings <larry at hastings.org>:
>> This PEP proposes a backwards-compatible syntax that should
>> permit implementing any builtin in pure Python code.
>
> This is rather too strong. You can certainly implement them; you just
> have to implement the argument parsing yourself. Python's
> call/signature syntax is already extremely expressive, and resolving
> call arguments to formal parameters is already a complicated (and
> slow) process. Implementing functions with such strange argument
> semantics is hardly common enough to justify the whole grouping syntax
> proposed in this PEP. -1 to that. I think I can live with "/", but
> YANGTNI still.

I am for having a way to succintly properly describe the signature of C 
in the manual and docstrings and help output. As it is now, the only 
safe thing to do, without trial and exception, is to assume positional 
only unless one knows otherwise.

But the syntax should only be as complicated as needed for 'most' C 
functions. If there are a few complicated oddballs, perhaps they could 
be simplified, or given a special-case explanation.

-- 
Terry Jan Reedy