c# - 在 C# 中使用接口(interface)作为 "out"参数

Question

如何在另一个接口(interface)的方法中使用一个接口(interface)或抽象类作为“out”参数？难道我不能将一个接口(interface)用作另一个接口(interface)中的输出参数，然后在我实际调用该方法时让它接受任何实现该接口(interface)的类吗？

我需要一个 Transaction 接口(interface)，它有一个返回 bool 并填充“Response”对象的方法，但是对于 Transaction 接口(interface)的每个不同实现，该响应对象是一个不同的派生对象。提前致谢。

namespace csharpsandbox
{
class Program
{
    static void Main(string[] args)
    {
        TransactionDerived t = new TransactionDerived();
        t.Execute();
    }
}


public interface ITransaction
{
    bool Validate(out IResponse theResponse);
}

public interface IResponse { }



public class ResponseDerived : IResponse
{
    public string message { get; set; }

}

public class TransactionDerived : ITransaction
{
    public bool Validate(out IResponse theResponse) {

        theResponse = new ResponseDerived();
        theResponse.message = "My message";
        return true;
    }

    public void Execute()
    {
        ResponseDerived myResponse = new ResponseDerived();

        if (Validate(out myResponse))
            Console.WriteLine(myResponse.message);
    }
}
}

Answer 1

只要您适本地进行转换，您当前的实现就会工作:

public class TransactionDerived : ITransaction
{
    public bool Validate(out IResponse theResponse)
    {    
        theResponse = new ResponseDerived();
        ((ResponseDerived)theResponse).message = "My message";

        return true;
    }

    public void Execute()
    {
        IResponse myResponse;

        if (Validate(out myResponse))
            Console.WriteLine(((ResponseDerived)myResponse).message);
    }
}

然而，这很困惑。您可以通过使用通用接口(interface)来避免强制转换:

public interface ITransaction<T> where T : IResponse
{
    bool Validate(out T theResponse);
}

public class TransactionDerived : ITransaction<ResponseDerived>
{
    public bool Validate(out ResponseDerived theResponse)
    {    
        theResponse = new ResponseDerived();
        theResponse.message = "My message";

        return true;
    }

    public void Execute()
    {
        ResponseDerived myResponse;

        if (Validate(out myResponse))
            Console.WriteLine(myResponse.message);
    }
}