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PEP 572: Python assignment expressions has been accepted

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317 points est | 2 comments | 03 Jul 18 08:30 UTC | HN request time: 0.419s | source
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BerislavLopac ◴[03 Jul 18 10:24 UTC] No.17448998[source]▶
I would like to see adding a comprehension-like filtering clause to for-statements:

    for n in range(100) if n%2:
        print(f'{n} is odd number')
Does anyone know if there is a PEP covering that?
replies(5): >>17449022 #>>17449029 #>>17449035 #>>17449036 #>>17452328 #
keedon ◴[03 Jul 18 10:35 UTC] No.17449036[source]▶

  for n in [i for i in range(100) if i%2 == 0]:
    print n
Will work (if a bit repetitive looking)
replies(1): >>17449104 #
1. BerislavLopac ◴[03 Jul 18 10:54 UTC] No.17449104[source]▶
It's not just repetitive; this particular example actually creates a list before starting the external loop -- imagine it with range(100000000) or something. It is better if you replace [] with (), which creates a generator.
replies(1): >>17449881 #
2. Herald_MJ ◴[03 Jul 18 13:18 UTC] No.17449881[source]▶
`range()` also takes an optional `step` argument which would help here.