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PEP 572: Python assignment expressions has been accepted

(groups.google.com)
317 points est | 1 comments | 03 Jul 18 08:30 UTC | HN request time: 0.208s | source
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oooooof ◴[03 Jul 18 09:00 UTC] No.17448560[source]▶
What is it? The link points to a discussion more deep than I’m willing to read.
replies(10): >>17448567 #>>17448570 #>>17448571 #>>17448572 #>>17448575 #>>17448579 #>>17448584 #>>17448591 #>>17448617 #>>17448638 #
est ◴[03 Jul 18 09:03 UTC] No.17448572[source]▶
It's a controversial PEP https://www.python.org/dev/peps/pep-0572/ which allows you to write Python like this:

    def foo():
        if n := randint(0, 3):
            return n ** 2
        return 1337


    [(x, y, x/y) for x in input_data if (y := f(x)) > 0]
replies(7): >>17448580 #>>17448633 #>>17448694 #>>17448731 #>>17448946 #>>17449000 #>>17449023 #
1. i_do_not_agree ◴[03 Jul 18 10:25 UTC] No.17449000[source]▶
This is horrible. It looks like ":=" is a comparison operator. The last line is dangerously close to Erlang list comprehensions:

[ {X, Y, X/Y} || X <- Some_Function (), Y <- Some_Other_Function () ]

And people bitch about Erlang syntax.

Edit: "/" is the division operator