我有一个协议,Address
,它继承自另一个协议,Validator
,并且Address
在扩展中满足了Validator
的要求。
还有另一个协议FromRepresentable
,它有一个associatedType
(ValueWrapper
)的要求,应该是Validator
。
现在,如果我尝试将Address
用作associatedType
,那么它无法编译。它说:
推断类型“Address”(通过匹配要求“valueForDetail”)无效:不符合“Validator”。
这种用法是否非法?我们不应该能够将Address
用作Validator
吗,因为所有的Addresses
都是Validator
?
下面是我正在尝试的代码片段。
enum ValidationResult {
case Success
case Failure(String)
}
protocol Validator {
func validate() -> ValidationResult
}
//Address inherits Validator
protocol Address: Validator {
var addressLine1: String {get set}
var city: String {get set}
var country: String {get set}
}
////Fulfill Validator protocol requirements in extension
extension Address {
func validate() -> ValidationResult {
if addressLine1.isEmpty {
return .Failure("Address can not be empty")
}
return .Success
}
}
protocol FormRepresentable {
associatedtype ValueWrapper: Validator
func valueForDetail(valueWrapper: ValueWrapper) -> String
}
// Shipping Address conforming to Address protocol.
// It should also implicitly conform to Validator since
// Address inherits from Validator?
struct ShippingAddress: Address {
var addressLine1 = "CA"
var city = "HYD"
var country = "India"
}
// While compiling, it says:
// Inferred type 'Address' (by matching requirement 'valueForDetail') is invalid: does not conform
// to 'Validator'.
// But Address confroms to Validator.
enum AddressFrom: Int, FormRepresentable {
case Address1
case City
case Country
func valueForDetail(valueWrapper: Address) -> String {
switch self {
case .Address1:
return valueWrapper.addressLine1
case .City:
return valueWrapper.city
case .Country:
return valueWrapper.country
}
}
}
更新: 提交了一个错误报告。