Yeah I'm referring to polymorphism. If I want to provide some sort of interface for my users that let them build any type of range at runtime, or even a range of ranges, then there's polymorphism involved. Other than polymorphism there's no other way a function can take or return a generic range type at runtime without know its exact type at compile-time.
Of course a polymorphic range of ranges is going to be a performance bottleneck due to virtual function calls, so it doesn't make sense for ranges to be polymorphic in the first place. I don't have a real use-case for these kinds of runtime-manipulated range types yet. I'd have to build something before I could make some kind of a case for them. So I'm really just speculating on what I need, and I'm experimenting with what ranges have to offer. I'll see how far I can go with the typeof() trick. :)
