Well, there's the old Component Object Model and cousins ... under this model an object a encountering a new object b will, essentially, ask 'I need this service performed, can you perform it for me?' If b can perform the service, a makes use of it; if not, not.
Another technique that occurs to me is from type theory ... here, instead of objects we'll talk in terms of values and functions, which have types. So e.g. a function a encountering a new function b will examine b's type and thereby figure out if it can/should call it or not. E.g., b might be called toJson and have type (in Haskell notation) ToJson a => a -> Text, so the function a knows that if it can give toJson any value which has a ToJson typeclass instance, it'll get back a Text value, or in other words toJson is a JSON encoder function, and thus it may want to call it.
Another technique that occurs to me is from type theory ... here, instead of objects we'll talk in terms of values and functions, which have types. So e.g. a function a encountering a new function b will examine b's type and thereby figure out if it can/should call it or not. E.g., b might be called toJson and have type (in Haskell notation) ToJson a => a -> Text, so the function a knows that if it can give toJson any value which has a ToJson typeclass instance, it'll get back a Text value, or in other words toJson is a JSON encoder function, and thus it may want to call it.