How to change a target using Castle DynamicProxy

Question

I am trying to understand Castle's DynamicProxy and the thing I would like to do is to change the target of the generated proxy at runtime.

Something like this...

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Castle.DynamicProxy;

namespace ConsoleApplication16
{
    class Program
    {
        static void Main(string[] args)
        {
            IFoo foo = new Foo("Foo 1");

            IFoo foo2 = new Foo("Foo 2");

            foo.DoSomething("Hello!");

            ProxyGenerator generator = new ProxyGenerator();
            IFoo proxiedFoo = generator.CreateInterfaceProxyWithTarget<IFoo>(foo);

            proxiedFoo.DoSomething("Hello proxied!");

            (proxiedFoo as IChangeProxyTarget).ChangeProxyTarget(foo2); // cast results in null reference

            proxiedFoo.DoSomething("Hello!");
        }
    }
}

I thought the generated proxy would implement IChangeProxyTarget but the cast to the interface results in a null reference.

How can I change the target of a generated proxy at runtime?

Update As mentioned in an answer, I tried using CreateInterfaceProxyWithTargetInterface and I'm still unable to cast to IChangeProxyTarget to change the target.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Castle.DynamicProxy;

namespace ConsoleApplication16
{
    class Program
    {
        static void Main(string[] args)
        {
            IFoo foo = new Foo("Foo 1");

            IFoo foo2 = new Foo("Foo 2");

            foo.DoSomething("Hello!");

            ProxyGenerator generator = new ProxyGenerator();
            IFoo proxiedFoo = generator.CreateInterfaceProxyWithTargetInterface<IFoo>(foo);

            proxiedFoo.DoSomething("Hello proxied!");

            IChangeProxyTarget changeProxyTarget = proxiedFoo as IChangeProxyTarget;

            if (changeProxyTarget == null) // always null...
            {
                Console.WriteLine("Failed");
                return;
            }

            changeProxyTarget.ChangeProxyTarget(foo2);

            proxiedFoo.DoSomething("Hello!");
        }
    }
}

Answer 1

use CreateInterfaceProxyWithTargetInterface

That one will allow you to change the proxy/invocation target.

Also the IChangeProxyTarget is implemented by invocation type, not the proxy itself.