How to access proxied object using impromptu-interface

Question

How can I get access to the Duck Typed proxied object when using impromptu-interface. consider my code that illustrates my example where I get a InvalidCastException when I try to cast my Duck Typed Object to the proxied Object:

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());
        }
    }
}

Exception is as follows:

An unhandled exception of type 'System.InvalidCastException' occurred in ConsoleApplication1.exe

Additional information: Unable to cast object of type 'ActLike_IPondBird_c7dd53902ec74f01a3844d4789244ea3' to type 'ConsoleApplication1.Duck'.

Can you please show the part of the documentation that leads you to believing that this should work? There is a misunderstanding somewhere here and that documentation allows me to more easily explain it to you. — Daniel Hilgarth, Apr 04 '16 at 11:25
It looks like you can use `Impromptu.UndoActLike(myInterface)` to get the original (wrapped) object back. — Pieter Witvoet, Apr 04 '16 at 11:30

score 4 · Accepted Answer · answered Apr 04 '16 at 11:25

You can't. You can think about line

IPondBird myInterface = Impromptu.ActLike(thing);

As something like

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

That being said you can make the reference to native object part of the contract itself - like:

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;

Excellent answer, tested it now and it Works perfectly. Well, back to the pond... :) — RedStar72, Apr 04 '16 at 11:51

score 2 · Answer 2 · answered Feb 08 '18 at 23:19

2

When you use impromptu interface, the generated proxy always has an explicit interface implementation for IActLikeProxy.

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

answered Feb 08 '18 at 23:19

jbtule

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How to access proxied object using impromptu-interface

2 Answers2