On 11/30/18 10:57 AM, Morten W. Petersen wrote:
> On Fri, Nov 30, 2018 at 4:25 PM Dan Sommers
<2qdxy4rzwzuui...@potatochowder.com> wrote:
>> Python validates that the right hand side contains exactly the right
>> number of elements before beginning to unpack, presumably to ensure a
>> successful operation before failing part way through.
> Hm. Well I like the simplicity and abstraction of Python, it makes it
> a very productive language.
Agreed, and hold that thought.
> But since you mention it, why is it necessary to ensure a successful
> operation?
>
> Is it so that when
>
> a,b,c = [1,2]
>
> fails, none of the variables a,b,c have been assigned to, and because
> of that, one avoids "rolling back" any assignment that would have been
> done without checking the right-hand argument first ?
That's what I was getting at, but apparently failed to express clearly.
Yes, there are use cases for a short iterator just not assigning the
rest of the variables, and for a long iterator using only what it needs,
but also explicit is better than implicit, and errors should never pass
silently, and other bits of wisdom learned from horrible debugging
experiences.
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