Looks like the delegate / data source pattern [1] which is prevalent in Cocoa programming.<p>[1] <a href="https://developer.apple.com/library/archive/documentation/General/Conceptual/CocoaEncyclopedia/DelegatesandDataSources/DelegatesandDataSources.html" rel="nofollow">https://developer.apple.com/library/archive/documentation/Ge...</a>
Congratulations to Martin Fowler on inventing reader monads with context objects!<p>Lets hope next time it doesn't take him 2 decades of ignoring Haskell inventions to actually find out if it is a good invention!<p>/s in case it's not obvious