Question

使用impromptu-interface时如何访问Duck Typed代理对象。考虑我的代码，说明我的示例，当我尝试将Duck类型对象强制转换为代理对象时，我得到InvalidCastException：

using System;
using ImpromptuInterface;

namespace ConsoleApplication1
{
    public class Duck
    {
        public string Says { get; set; }

        public int GetNumberOfQuacksPerMinute()
        {
            return 42;
        }
    }

    public interface IPondBird
    {
        string Says { get; set; }
    }

    class Program
    {
        static void Main(string[] args)
        {
            // Duck says Quack! Quack!! Quack!!!
            var thing = new Duck { Says = "Quack! Quack!! Quack!!!" };

            IPondBird myInterface = Impromptu.ActLike(thing);

            // ...

            // Later on, I want to get access to a proxied object, but I 
            // get a InvalidCastException here
            Duck proxiedObject = (Duck) myInterface;
            Console.WriteLine("Duck # quacks per minute: " 
                + proxiedObject.GetNumberOfQuacksPerMinute());
        }
    }
}

例外情况如下：

发生了类型为“System.InvalidCastException”的未处理异常   在ConsoleApplication1.exe中

附加信息：无法投射类型的对象   'ActLike_IPondBird_c7dd53902ec74f01a3844d4789244ea3'键入   'ConsoleApplication1.Duck'。

Answer 1

你做不到。你可以考虑一下

IPondBird myInterface = Impromptu.ActLike(thing);

类似

public class Wrapper : IPondBird 
{
  public Wrapper(Duck duck) { ... }
}
IPondBird myInterface = new Wrapper(thing);

话虽如此，您可以在合同本身中引用本机对象部分 - 例如：

public interface IPondBird
{
    string Says { get; set; }
    object NativeObject { get; }
}

public class Duck
{
    public string Says { get; set; }

    public int GetNumberOfQuacksPerMinute()
    {
        return 42;
    }

    public object NativeObject { get { return this; } }
}

IPondBird myInterface = Impromptu.ActLike(thing);   
var duck = (Duck)myInterface.NativeObject;

Answer 2

使用即兴接口时，生成的代理始终具有IActLikeProxy的显式接口实现。

IPondBird myInterface = Impromptu.ActLike(thing);   
var duck = (Duck)((IActLikeProxy)myInterface).Original;

如何使用即兴接口访问代理对象

2 个答案: