IMO this is a purism that have little, if any place in language restrictions. I see that not allowing. "run once" iterables could indeed void attempts to write "deliberatly non cooperative code" - but can it even be reliably detected?
The other changes seem just to break backwards compatibility for little or no gain at all. On Fri, Mar 18, 2022 at 6:57 AM Ronald Oussoren via Python-Dev < python-dev@python.org> wrote: > > > On 18 Mar 2022, at 10:29, Serhiy Storchaka <storch...@gmail.com> wrote: > > Currently __slots__ can be either string or an iterable of strings. > > 1. If it is a string, it is a name of a single slot. Third-party code > which iterates __slots__ will be confused. > > 2. If it is an iterable, it should emit names of slots. Note that > non-reiterable iterators are accepted too, but it causes weird bugs if > __slots__ is iterated more than once. For example it breaks default > pickling and copying. > > I propose to restrict the type of __slots__. Require it always been a > tuple of strings. Most __slots__ in real code are tuples. It is rarely we > need only single slot and set __slots__ as a string. > > It will break some code (there are 2 occurrences in the stdlib an 1 in > scripts), but that code can be easily fixed. > > > Pydoc supports __slots__ that is a dict, and will use the values in the > dict als documentation for the slots. I’ve also seen code using > ``__slots__ = “field1 field2”.split()``. I don’t particularly like this > code pattern, but your proposal would break this. > > Also note that __slots__ only has a side effect during class definition, > changing it afterwards is possible but has no effect (“class Foo: pass; > Foo.__slots__ = 42”). This surprised my recently and I have no idea if this > feature is ever used. > > Ronald > > > _______________________________________________ > Python-Dev mailing list -- python-dev@python.org > To unsubscribe send an email to python-dev-le...@python.org > https://mail.python.org/mailman3/lists/python-dev.python.org/ > Message archived at > https://mail.python.org/archives/list/python-dev@python.org/message/E32BRLAWOU5GESMZ5MLAOIYPXSL37HOI/ > Code of Conduct: http://python.org/psf/codeofconduct/ > > > — > > Twitter / micro.blog: @ronaldoussoren > Blog: https://blog.ronaldoussoren.net/ > > _______________________________________________ > Python-Dev mailing list -- python-dev@python.org > To unsubscribe send an email to python-dev-le...@python.org > https://mail.python.org/mailman3/lists/python-dev.python.org/ > Message archived at > https://mail.python.org/archives/list/python-dev@python.org/message/YQUWR7CYKNM65HR5FZQ3BANR5SNNK6N6/ > Code of Conduct: http://python.org/psf/codeofconduct/ >
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