[Python-Dev] What's the status of PEP 505: None-aware operators?

[Eric Fahlgren]

On Thu, Nov 30, 2017 at 2:48 AM, Andrea Griffini <agriff at tin.it> wrote:

> Not really related but the PEP says that arguments in Python are evaluated
> before the function (as a reason to reject the idea of None-aware function
> call) but this is not the case:
>

​I think you're missing something here, since it seems clear to me that
indeed the arguments are evaluated prior to the function call.​  Maybe
unrolling it would help?  This is equivalent to the body of your lambda,
and you can see that the argument is evaluated prior to the call which
receives it.

>>> func = f()
>>> arg = g()
>>> func(arg)

    >>> import dis
>     >>> dis.dis(lambda : f()(g()))
>       1           0 LOAD_GLOBAL              0 (f)
>                   3 CALL_FUNCTION            0
>

​Call 'f()' with all of its arguments evaluated prior to the call (there
are none, that's the '0' on the CALL_FUNCTION operator).
​


>                   6 LOAD_GLOBAL              1 (g)
>                   9 CALL_FUNCTION            0
>

​Next, evaluate the arguments for the next function call.​
​  ​
​Call 'g()' with all of its arguments evaluated.
​

>                  12 CALL_FUNCTION            1
>

​Call the function that 'f()' returned with its argument ('g()') evaluated.
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