> I have some ID types that are simple ints coming back from a database. I
> wanted to improve type safety so I don’t accidentally assign product IDs to
> user IDs, etc. I want to be able to print it and use it as a dictionary key.
> So it is a trivial wrapper of Int. E.g.
>
> struct CustomerID: Hashable, CustomStringConvertible {
> init(_ value: Int) { self.value = value }
> let value: Int
> var hashValue: Int { return value.hashValue }
> var description: String { return String(value) }
> }
>
> func ==(lhs: CustomerID, rhs: CustomerID) -> Bool {
> return lhs.value == rhs.value
> }
Rather than going the protocol route, how about a generic type?
struct ID<IdentifiableType: Identifiable>: Hashable,
CustomStringConvertible {
init(_ value: Int) { self.value = value }
let value: Int
var hashValue: Int { return value.hashValue }
var description: String { return String(value) }
}
func ==<T: Identifiable>(lhs: ID<T>, rhs: ID<T>) -> Bool {
return lhs.value == rhs.value
}
protocol Identifiable {
var id: ID<Self>? { get }
}
struct Customer: Identifiable {
var id: ID<Customer>?
}
--
Brent Royal-Gordon
Architechies
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