Given we now have precedent in the form of the derived Codable conformance
coming in Swift 4.0,
it begs the question why we don’t offer the same behavior for value types that
declare themselves to be Equatable
and have all Equatable properties. E.g.
struct A: Equatable {
let foo: String
let bar: Int
}
struct B: Equatable {
let baz: Double
}
struct C: Equatable {
let a: A
let b: B
}
let a = A(foo: “hello”, bar: 1)
let a2 = A(foo: “hello”, bar: 2)
a == a2 // false
let b = B(baz: 3.1)
let c = C(a: a, b: b)
le c2 = C(a: a2, b: b)
c == c2 // false
You would always be free to shadow the provided implementation:
extension A {
func ==(lhs: A, rhs: A) {
return lhs.foo == rhs.foo
}
}
a == a2 // true
It’s up for debate whether this should apply to reference types, or Hashable,
but at a bare minimum we should
offer it for value types consisting of Equatable value types that explicitly
declare but don’t implement the conformance.
Thanks!
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