[Python-Dev] PEP 572: Assignment Expressions

[Chris Angelico]

On Tue, Apr 24, 2018 at 5:12 PM, Greg Ewing <greg.ewing at canterbury.ac.nz> wrote:
> Chris Jerdonek wrote:
>
>>>> if (diff := x - x_base) and (g := gcd(diff, n)) > 1:
>
>
>> "if diff, which we let equal x - x_base, and g, which ..." or
>> "if diff, which we set equal to x - x_base, and g, which ...." or
>> "if diff, which we define to be x - x_base, and g, which ...." or
>> "if diff, which we define as x - x_base, and g, which ....." etc.
>
>
> How about "being" as a keyword:
>
>   if (diff being x - x_base) and (g being gcd(diff, n)) > 1:
>     return g
>
> An advantage is that you're not likely to be tempted to write
>
>    diff being x - x_base
>
> on its own as a statement.

Considering that we have ':=', 'as', and 'from', I very much doubt
that *any* proposal requiring a new keyword is going to fly. The bar
for creating new keywords is a lot higher than that. We hashed out a
lot of this on python-ideas; it's almost certainly a waste of time to
go through it all again now. I have no intention of editing the PEP to
recommend a brand new keyword.

ChrisA