How can I work with methods that have parameters of a protocol type without knowing the specific type of the protocol?
For instance the following example would produce a "Protocol 'Result' as a type cannot conform to the protocol itself" error, because swift does not allow to call the method with an object of the Result
protocol
Example:
protocol Result {
var foo: String { get }
}
struct ResultImpl: Result {
var foo = "foo"
}
struct ResultImpl2: Result {
var foo = "foo2"
}
protocol Calculator {
func processResult<T: Result>(_ result: T)
}
struct CalculatorImpl: Calculator {
func processResult<T: Result>(_ result: T) {
let _ = result.foo
}
}
func test(){
let result: Result = getResult() // get anything that implements Result interface
let calc = CalculatorImpl();
let _ = calc.processResult(result) // Protocol 'Result' as a type cannot conform to the protocol itself
}
func getResult() -> Result {
return Int.random(in: 0...1) == 0 ? ResultImpl(): ResultImpl2();
}
CodePudding user response:
The function processResult
shouldn't be generic, a generic will require a concrete type that conforms to Result
at compile time.
func processResult(_ result: Result)