[Python-Dev] Call for prudence about PEP-572

[David Mertz]

The case I find more reasonable is assignment in earlier arguments:

z = something ()
w = myfun(x := get_data(), y=calculate(x, z))

I would probably recommend against that in code review, but it's not
absurdly obfuscated.

On Sun, Jul 8, 2018, 1:15 PM Giampaolo Rodola' <g.rodola at gmail.com> wrote:

>
>
> On Sun, Jul 8, 2018 at 6:45 PM Steve Holden <steve at holdenweb.com> wrote:
>
>> On Sun, Jul 8, 2018 at 10:41 AM, Giampaolo Rodola' <g.rodola at gmail.com>
>> wrote:
>>
>>> ​[...]
>>> I find that (space between the parentheses of a function call
>>> statement) too unnatural as a place where to put an assignment. It is
>>> not even "guarded" by a keyword like "if" or  "while" which can help as
>>> indicators that an assignment may occur. Also, I think it's way too easy to
>>> confuse it with a keyword argument:
>>>
>>>     >>> foo(x = 1)  # keyword arg
>>>     >>> foo(x := 1)  # assignment + value passing
>>> ​[...]
>>>
>>
>> ​But the PEP 8 spellings are​
>>
>>     foo(x=1)
>>
>> and
>>
>>    f(x := 1).
>>
>> The extra spacing makes it obvious that this isn't a regular named
>> argument.
>>
>
> What if the author of the code I'm reading didn't respect PEP-8? I don't
> think it's fair to invoke PEP-8 as a counter-measure to obviate a syntax
> which can clearly be mistaken with something else simply by omitting 2
> spaces. Not to mention that I don't see why anyone would want to declare a
> variable in there in the first place.
>
> --
> Giampaolo - http://grodola.blogspot.com
>
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