Hi, would you mind supporting this too #79?

The refactor's elimination of the list is a significant improvement. The ordering preserved by the interface for intersection is also an improvement.

FYI, You can make intersection a lot faster (linearithmic in the smallest set rather than linear in the first set) if you implement it like this: https://discuss.python.org/t/add-orderedset-to-stdlib/12730/83?u=neilgirdhar. This comes at the cost of storing some integers, which may or may not be desirable.

I also don't see the point of add returning the length of the set. It's neither in the ABC nor is it particularly helpful.

@twiddli pretty sure he can't support it since dicts don't have efficient indexing.

@twiddli @NeilGirdhar
Thanks for your inputs, I'll look into it in about 2 weeks when I'm back from a holiday.

@idanmiara a few questions.

1. "Both have similar interfaces but differ in respect of their implementation and performance." I'm curious to know a listing of exactly how the interfaces differ if at all.

2. Why the name StableSet? And why do you call the dict-based set StableSet and the list-based set OrderedSet? Is the choice arbitrary? If the interfaces are the exact same (except for performance trade-offs or how equality is calculated) maybe they could all share a name (OrderedSet would be my suggestion) and the "style" could be selected with an input option during instantiation?

3. Have you seen this thread? I wonder if anything there is helpful.

@jagerber48 thanks, I'll look into it when I'm back from my holiday.