[Python-Dev] PEP 457: Syntax For Positional-Only Parameters (original) (raw)

Joao S. O. Bueno jsbueno at python.org.br
Wed Oct 9 03:57:51 CEST 2013

I am -1 for the optional parameters and grouping stuff - no need to make complicated stuff easier to do just because "range" semantics is strange to start with. (And one can implement a range-like funciton explictly parsing the parameters if needed be.)

As for the "/" delimiting positional only parameters - I think it would be nice to have. -but just that - mandatory positional only parameters.

Apart from that, I could not figure if the PEP covers a situation where the name of a positional-only parameter is passed in as a kwarg -

def a([b],/,**kw): print (b)

does calling "a(b=5)" should raise a TypeError, or put "5" in """kw["b"]""" and leave "b" as "undefined" ?

js -><-

On 8 October 2013 22:31, Benjamin Peterson <benjamin at python.org> 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.

-- Regards, Benjamin

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