> On 18 Mar 2022, at 10:29, Serhiy Storchaka <[email protected]> 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
>
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