Forbid initializing 2 or more variables on one line

[orsinium]

Rule request

Thesis

# bad
ab, cd = [], []

# good
ab = []
cd = []

Reasoning

Decrease unnecessary code line complexity.

[sobolevn]

One more thing, unpacking is a good thing and should be allowed: a, b = some_tuple()
The thing about this example is that [], [] does not look like a real tuple. But, for example: x, y = (1, 2) looks pretty readable to me.

So, we need to find a balance between an obviously good idea - one assignment per line - and some real-world usages, when this rule is not applicable.

[orsinium]

One more thing, unpacking is a good thing and should be allowed: a, b = some_tuple()

Exactly 👍🏿

But, for example: x, y = (1, 2) looks pretty readable to me.

I don't think it will drop readability if it is on separate lines. Moreover, now I work on a codebase that has plenty of it and I always miss where the initialization of the second variable (y in your example) happens. So, I don't have cases in mind when one-line initialization is useful.

Ok, there is one case: swapping variables (x, y = y, x). However, I can't recall any case when I actually used it. Non-recursive GCD, maybe.

[sobolevn]

swapping variables

Yes, sometimes I use this when doing non-recursive things like tree traversal.

[dreamflasher]

I disagree that x, y = (1, 2) is particularly good style. I vouch for forbidding assigning more than 2 variables on one line. On the rare occasion that someone needs to implement GCD they can use noqa.

[f1sherFM]

@sobolevn Can i take this?