On Fri., Oct. 11, 2019, 2:38 a.m. Neil Girdhar, <mistersh...@gmail.com> wrote:
> > > On Fri, Oct 11, 2019 at 2:28 AM Andrew Barnert <abarn...@yahoo.com> wrote: > >> > On Oct 10, 2019, at 22:13, Neil Girdhar <mistersh...@gmail.com> wrote: >> > >> > That's funny, I always thought of that as legacy. The iterator >> protocol has been a special case in so many proposals I've seen on this >> list. I think it's really ugly. Instead of >> collections.abc.OldStyleSequence, what do you think of adding something >> like InfiniteSequence to collections.abc instead? It's basically Sequence >> without __len__, __reversed__, or __count__. I don't see it getting much >> use though. >> >> Are you proposing that this type isn’t allowed to have those methods (as >> opposed to just not being required to)? > > > Not required. Just like if we added a row to the table. So, the point of > this mixin would be to implement __contains__ __iter__ and __index__ given > __getitem__. > > >> If so that would be a unique ABC, and a pretty weird one. If not, isn’t >> this exactly equivalent to the original proposal, but just with a different >> name? And I think it’s a pretty misleading name. Especially if the subclass >> hook is structural (method-check), because then it would pick up Sequence >> and Mapping types even though they aren’t infinite sequences. For that >> matter, not even every useful old-style sequence is infinite; that’s just >> the most obvious example everyone comes up with first. >> > > Yeah, those are all good points. After sending, I realized, that it would > be nicer as a base class of Sequence. I guess I'm for the proposal then. > I skipped reading the big debate about structural checks because I think if > you really care about this, you should probably either inherit from the ABC > or register yourself with it. > > Anyway, I guess we pretty much agree then. I just wanted to push against > legitimizing the sequence protocol in favor of explicitly inheriting from a > mixin (whatever you want to call it, GenericSequence? AbstractSequence? > PossiblyInfiniteSequence?) Inheritance like this is a nice declaration of > intent. Even if you just implemented __getitem__, I think you would have > to have a comment to make the code clear anyway. > > >> Anyway, I don’t want to put words in Steven’s mouth; maybe this would fit >> what he wanted. But I suspect it wouldn’t. >> >
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