[Python-Dev] Examples for PEP 572

[Steven D'Aprano]

On Tue, Jul 03, 2018 at 09:54:22PM -0400, Terry Reedy wrote:


> >     results = [(x, y, x/y) for x in input_data for y in [f(x)] if y > 0]
> 
> Would (f(x),) be faster?

There is a deferred feature request to optimize "for x in [item]" as 
equivalent to "for x in (item,)", to avoid constructing a list:

https://bugs.python.org/issue32856

Since it only affects the internal byte-code, not visible semantics 
(aside from speed and memory) I think that's a neat micro-optimization 
regardless of whether it is applied to comprehensions or regular 
for-loops or both.




-- 
Steve