Question

我有一个通用Struct数组，该结构的通用类型扩展了类ResponseBase。在我尝试附加到responseMapping数组的函数中，但没有运气，它总是出现以下错误：Error: Cannot convert value of type 'ResponseMap<ResponseType>' to expected argument type 'ResponseMap<ResponseBase>'。我已经尝试添加Any，AnyClass，AnyObject或任何Any作为Type，但是它也没有真正实现。

我尝试使用Type Erasure来做到这一点，但我感到困惑，于是我放弃了。有人知道如何正确执行此操作吗？

代码

struct ResponseMap<ResponseType: ResponseBase> {
    var fulfill: (ResponseType) -> ()
}

public class MessengerTest {
    var responseMapping = [ResponseMap]()

    func send<ResponseType, Type>(_ message: Type) -> Promise<ResponseType> where ResponseType: ResponseBase, Type: Base<ResponseType> {
        return Promise<ResponseType> { resolver in
            let map = ResponseMap(fulfill: resolver.fulfill)
            self.responseMapping.append(map)       <---- Error
        }
    }
}

更新这是引发相同错误但没有PromiseKit的代码。

class Promise<U> {
  let fulfill: (U)->Void

  init() {
    fulfill = {U in
      print("fulfill")
    }
  }
}

class Base {

}

class Response: Base {

}

class Response1: Base {

}

struct ResponseMap<U: Base> {
  let fulfill: (U)->Void
}


var responseMapping = [ResponseMap]()

let promise1 = Promise<Response>()
let promise2 = Promise<Response1>()

let map1 = ResponseMap(fulfill: promise1.fulfill)
let map2 = ResponseMap(fulfill: promise2.fulfill)

responseMapping.append(map1)
responseMapping.append(map2)

将通用结构追加到数组

0 个答案: