Implicitly, IIRC, the optimal ratio is 5-20:1. Your interface must cover 5-20 cases for it have value. Any fewer, the additional abstraction is unneeded complexity. Any more, and your abstraction is likely too broad to be useful/understandable. The example he gives specifically was considering the number of subclasses in a hierarchy.
It’s like a secret unlock code for domain modeling. Or deciding how long functions should be (5-20 lines, with exceptions).
It’s like a secret unlock code for domain modeling. Or deciding how long functions should be (5-20 lines, with exceptions).
I agree, hugely usual principle.