Op 4/03/2022 om 8:18 schreef Chris Angelico:
On Fri, 4 Mar 2022 at 18:13, Dieter Maurer <die...@handshake.de> wrote:
> One of my use cases for `for - else` does not involve a `break`:
> the initialization of the loop variable when the sequence is empty.
> It is demonstrated by the following transscript:
>
> ```pycon
> >>> for i in range(0):
> ... pass
> ...
> >>> i
> Traceback (most recent call last):
> File "<stdin>", line 1, in <module>
> NameError: name 'i' is not defined
> >>> for i in range(0):
> ... pass
> ... else: i = None
> ...
> >>> i
> >>>
> ```
>
> For this use case, `else` is perfectly named.
What's the point of this? Why not just put "i = None" after the loop?
As I understand it: range(0) is just a (bad) example, it's actually
about any arbitrary iterable. You don't know in advance if it's empty or
not, and you want i to be initialized in all cases. (I don't think I
have ever encountered that situation.)
You could easily solve this by placing "i = None" before the loop, but I
guess in situations where you want to initialize i with the result of an
expensive operation Dieter's method could be a reasonable solution.
This would actually be a good use case for computermaster360's proposal.
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