[Python-Dev] assignment expressions: an alternative proposal

[Chris Angelico]

On Wed, Apr 25, 2018 at 1:56 AM, Yury Selivanov <yselivanov.ml at gmail.com> wrote:
> On Tue, Apr 24, 2018 at 11:51 AM, Ethan Furman <ethan at stoneleaf.us> wrote:
>
>>> When I compare to variables from outer scopes they *usually* are on
>>> the *right* side of '=='.
>>
>>
>> You mean something like
>>
>>   if 2 == x:
>>
>> ?  I never write code like that, and I haven't seen it, either.
>
> Hm. I mean this:
>
>    const = 'something'
>
>    def foo(arg):
>      if arg == const:
>         do something
>
> Note that "const" is on the right side of "==".
>
> Would you write this as
>
>    def foo(arg):
>       if const == arg:
>
> ? ;)

That's assuming the global is a constant. What if it's a mode-setting marker?

def foo(arg):
    ...
    if output == "verbose" or (output != "quiet" and error_count):
        print("Arg foo'd", arg)
        print("Errors found:", error_count)

Then I would definitely put the variable first. And I know a lot of
people who would parenthesize the first condition in this.

ChrisA