The "Clean Break" would involve removing "split" from the RandomGen class and making a new class "SplittableGen" for this operation. The thought here is that not all generators can have a "split". Users of "split" would have to be explicit of their need for a Splittable generator.
The backward compatible change would keep "split" as a member of class "RandomGen" for which all instances would be constrained to also be instances of the "BasicRandomGen" class. BasicRandomGen would contain the traditional routines (next, genRange).
Removing the Read and Show constraints for splittable generators would be a Really Good Thing. It turns out implementing splittable generators efficiently (eg using Lennart's notion of splittable supplies) doesn't work in the presence of these constraints ---- or rather, one is faced with the choice of Read/Show yielding irreproducible results, or using an inefficient implementation of splittable supplies. -Jan-Willem Maessen