[英]Generics to return a struct of asked Type
I'm having a function like this: 我有这样的功能:
func someFunction<T: Codable>(x: Double, y: Double, outputClass: T, completionBlock: CompletionBlock)
the completionblock is: 的完成块是:
enum Result {
case success(Codable)
case failure(String?)
}
typealias CompletionBlock = (Result) -> Void
What I want to achieve is that when you call the function for example like this: 我想要实现的是,当您调用该函数时,例如:
someFunction(x: 12, y: 12, outputClass: Foo.self) { (result) in
switch result {
case .success(let result):
}
That my let result in the success case is of type Foo. 我成功的案例是Foo类型。
I have a Foo struct: 我有一个Foo结构:
struct Foo: Codable {
let content: String
}
Now when I try to call the function xCode tells me: 现在,当我尝试调用xCode函数时,它告诉我:
Argument type 'Foo.Type' does not conform to expected type 'Encodable'
But the struct conforms to the type Codable and that is encodable & decodable. 但是该结构符合可编码类型,即可编码和可解码。
Can someone explain me what I'm doing wrong? 有人可以解释我在做什么吗?
I think you need to wrap your function inside a generic class, and put the enum inside the class as well. 我认为您需要将函数包装在泛型类中,并将枚举也放入类中。 This way, you can use the generic parameter
T
of the class instead of the T
in the function. 这样,您可以使用类的通用参数
T
代替函数中的T
You also don't need the outputType
parameter. 您也不需要
outputType
参数。
class SomeClass<T: Codeable> {
class func someFunction(x: Double, y: Double, completionBlock: CompletionBlock) {
}
enum Result {
case success(T)
case failure(String?)
}
typealias CompletionBlock = (Result) -> Void
}
struct Foo: Codeable {
}
// usage
SomeClass<Foo>.someFunction(x: 0, y: 0) { (x) in
switch x {
case .success(let result):
// result is now of type Foo
case .failure:
break
}
}
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