It's certainly a contrived example. Actual code with such a mistake is generally far more subtle.
The mistake is that it's assigning a value within a clause of a conditional that won't be evaluated. Oh well. I'll suffer the then worsened zig-zaggy eye movements in code reviews caused by defining values at the end of expressions that reference them which fit on a single line. There are a number of bad examples for style guides in these threads. := I wasn't aware of this switch, thanks! http://coverage.readthedocs.io/en/latest/branch.html coverage run --branch code.py On Friday, April 27, 2018, Tim Peters <tim.pet...@gmail.com> wrote: > Wes, sorry, but I really don't follow what you're saying. For example, > > [Wes Turner <wes.tur...@gmail.com>] > > Do not do this: > > > > x = 2 > > if (x == 3) or (x := 3): > > print(x) > > > > What do we call that mistake? > > It displays 3 - while it appears to be silly code, there's nothing > about it that's undefined. So I fail to see how showing that example > anywhere would do anyone any good. > > You can do the same kind of thing today via, e.g., > > class Bindable: > def __init__(self, value): > self.bind(value) > > def bind(self, value): > self.value = value > return value > > def __bool__(self): > return bool(self.value) > > def __eq__(self, other): > return self.value == other > > def __str__(self): > return str(self.value) > > Then: > > >>> x = Bindable(2) > >>> if x == 3 or x.bind(3): > ... print(x) > 3 > > And I wouldn't put that example anywhere in any docs either ;-) >
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