Is this behavior of list iteration guaranteed by documentation anywhere? A quick search didn't yield any results for me.
If not, I suggest either: a) it gets documented so developers can rely on it, or b) the lack of guarantee is documented so that we can reserve a change of behavior later. Paul On Sun, 2021-10-10 at 13:17 +1300, Greg Ewing wrote: > On 9/10/21 11:24 am, Tyler Hou via Python-ideas wrote: > > Right now, the following code is valid in Python 3.9 (and > > infinitely loops): > > > > ``` > > lst = [1, 2, 3] > > for i in lst: > > lst.append(i) > > ``` > > > > 1. If the size of a list, set, or dict changes, invalidate all > > existing iterators to that containers. > > This would break Plex. I use a loop like that as part of the > NFA-to-DFA conversion to calculate the epsilon-closure of a > state (although obviously there are conditions on adding things > to the list that ensure it terminates). >
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