Local variable definition in Python list comprehension

[James Tsai]

在 2022年9月1日星期四 UTC+2 18:16:03，<Chris Angelico> 写道：
> On Fri, 2 Sept 2022 at 02:10, James Tsai <james... at gmail.com> wrote: 
> > 
> > Hello, 
> > 
> > I find it very useful if I am allowed to define new local variables in a list comprehension. For example, I wish to have something like 
> > [(x, y) for x in range(10) for y := x ** 2 if x + y < 80], or 
> > [(x, y) for x in range(10) with y := x ** 2 if x + y < 80]. 
> > 
> > For now this functionality can be achieved by writing 
> > [(x, y) for x in range(10) for y in [x ** 2] if x + y < 80]. 
> > 
> > Is it worthwhile to add a new feature like this in Python? If so, how can I propose this to PEP?
> Not everything has to be a one-liner. 
> 
> ChrisA

No but very often when I have written a neat list/dict/set comprehension, I find it very necessary to define local variable(s) to make it more clear and concise. Otherwise I have to break it down to several incrementally indented lines of for loops, if statements, and variable assignments, which I think look less nice.