gwynne/MAKVONotificationCenter — comment on commit 9db3c4de967796470fc5e043e4642a2973757d47
File: MAKVONotificationCenter.m line 176
By gwynne:

The thought behind the `hash` override as it stands is to allow these things to be stored in the helpers sets a bit more efficiently. I don't really know that it helps any, but I can't imagine that it hurts. The `isEqual:` override is more documentary than functional, showing that even if all parameters are equal, every observation is unique. That's implied by `NSObject`'s default implementation, but I found stating it explicitly in the code helped me think through some of the "find matching observations" logic further down.

(Really, though, the `hash` override is really an artifact of my original idea to let `NSSet` handle matching before I realized that every observation has to be unique. :)