不能专门化协议类型

Question

Swift5.7附带了主要的关联类型。我尝试使用这些代码，但它显示了错误:不能专门化协议类型'GenericDelegate‘

class BaseResponse {}
class ConcreteResponse: BaseResponse {}

protocol GenericDelegate<Response>: AnyObject {
    associatedtype Response: BaseResponse
    func didGetResponse(response: Response)
}


class BaseCGI<T:BaseResponse> {
    weak var delegate: (any GenericDelegate<T>)? //error: Cannot specialize protocol type 'GenericDelegate'

    func didGetResponse(response:T) {
        self.delegate?.didGetResponse(response: response)
    }
}

如何使具有指定关联类型的存在类型成为变量？

像这样使用：

class FooDelegate: GenericDelegate {
    func didGetResponse(response: ConcreteResponse) {
        //do something
   }

}

let cgi = BaseCGI<ConcreteResponse>
cgi.delegte = FooDelegate()
cgi.didGetResponse(ConcreteResponse())

Answer 1

在我看来，您必须使类BaseCGI在响应类型和委托类型上都是通用的。此外，您需要告诉编译器，委托的响应类型与类的响应类型相同。

class BaseCGI<Response: BaseResponse, Delegate: GenericDelegate> where Delegate.Response == Response {
    weak var delegate: Delegate?

    func didGetResponse(response: Response)  {
        self.delegate?.didGetResponse(response: response)
    }
}

然后创建一个实例，如

let cgi = BaseCGI<ConcreteResponse, FooDelegate>()