On Tue, Nov 28, 2017 at 2:35 AM, Steven D'Aprano <steve@pearwood.info> wrote:
In this case, there is a small but real benefit to counting the assignment targets and being explicit about the number of items to slice. Consider an extension to this "non-consuming" unpacking that allowed syntax like this to pass silently:
a, b = x, y, z
That ought to be a clear error, right? I would hope you don't think that Python should let that through. Okay, now we put x, y, z into a list, then unpack the list:
L = [x, y, z] a, b = L
That ought to still be an error, unless we explicity silence it. One way to do so is with an explicit slice:
a, b = L[:2]
I absolutely agree with this for the default case. That's why I am ONLY in favour of the explicit options. So, for instance: a, b = x, y, z # error a, b, ... = x, y, z # valid (evaluates and ignores z) ChrisA