#swift triple equality examples for #medium

triple-equalities.swift

struct Bread {
    let rating : Int
}
class Cheese {    
    let rating : Int
    init(rating: Int) {
        self.rating = rating
    }
}
var c1 = Cheese(rating: 0)
var c2 = Cheese(rating: 0)
var c3 = c1 // same reference
var c4 = Cheese(rating: 1)
c1 == c2 // error, == not defined
c1 === c2 // false
c3 === c1 // true
var b1 = Bread(rating: 0)
var b2 = Bread(rating: 0)
b1 == b2 // error, == not defined
b1 === b2 // error, they aren't references!
let cheeses = [c1, c2]
cheeses.contains(c1) // error, Cheese not Equatable
cheeses.contains { $0 === c1 } // true
cheeses.contains { $0 === c3 } // true
cheeses.contains { $0 === c4 } // false