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!
coverage run --branch code.py
On Friday, April 27, 2018, Tim Peters <
tim.peters@gmail.com> wrote:
Wes, sorry, but I really don't follow what you're saying. For example,
[Wes Turner <wes.turner@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 ;-)