Question

I want to build a dynamic proxy object to add certain functionality to an object.

basically i want to receive an object, wrap it with an object that looks identical to the original i got, and intercept all the calls.

class Wrapper : DynamicProxy// dynamic proxy is not a reall class, but i guess something like this exists...
{
    public static T Wrap(T obj)
    {
        return (T) new Wrapper(obj);
    }

    public override object InterceptCall(MethodInfo info, object[] args)
    {
        // do stuff
    }

}

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Just to clarify, I want to do something similar to the WCF channel factory…

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I’m adding a bounty, because I need a good way to proxy classes (not interfaces) and to handle non virtual methods (as if I inherited and added a methond under the “new” keyword).
I’m sure all this is very possible as the .Net does it.

Answer 1

I should have written this sooner, but never mind.

My issue had a special “gotcha” I needed to be able to proxy classes and not interfaces.

There are two solutions to this:

1. RealProxy and friends, basically means using .NET Remoting. Requires one to inherit from ContextBoundObject.

   • This approach takes advantage of “magic” provided by the .NET JIT compiler
     (which is hardcoded to specifically recognize RealProxy) to let you “override” non-virtual members.

2. Building a proxy using System.Reflection.Emit as done by spring you can also look at the code of their ProxyFactoryObject. Here are another three articles on the subject.

   • This approach has the crucial disadvantage of limiting you to overriding only virtual members.