Drop this in playground and your on your way:
protocol IPositional:class{}
class A: IPositional{}
class B: IPositional{}
let a: IPositional = A()
let b: IPositional = B()
let c: IPositional = a
a === b //false
a === c //true
NOTE:
the :class after the protocol name means that you derive only classes for the protocol, so it cant be a protocol for structs for instance, this in turn enables === operator for the protocol.
It also means that you are able to set variables via extension.
Tasks:
- Write an example of the use case for
variables via extension.