Question

I’m wondering if there is an IList<T> implementation that’s backed by a hash like HashSet<T> but offers indexed access?

To be clear, I’m not concerned on how to implement one, just wondering if anyone knows if it’s already available.

Answer 1

You could implement IList<T> yourself and keep two backing collections – a List<T> and a HashSet<T>. Basically get Visual Studio to provide a “throw exception” implementation for everything in IList<T>, then for each method work out whether you want to proxy it to the list or the set.

Of course you’d have to be careful for duplicates etc (define the behaviour of Add(x), Add(x), Remove(x), Contains(x) – you could end up with it in the list but not the set) but it wouldn’t be too hard.