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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: 0.2s | 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.
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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]
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chombier ◴[03 Jul 18 09:25 UTC] No.17448694[source]▶
Can somebody comment on why is this PEP controversial?
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1. est ◴[03 Jul 18 09:32 UTC] No.17448733[source]▶
For many people (including me) who learned Python the way that, in languages like C, the `if x=2` assignment combined with condition is an anti-pattern and prone to errors.

This PEP solves very little problem, saves a few characters of code, but adds complexity to readability.