Is it possible to store properties via opDispatch using tuples?

[Gary Willoughby]

What i would like to achieve is to dynamically assign and 
retrieve properties without declaring them first. For example:

class T
{
     public this()
     {
         this.foo = "bar";
     }
}

Ordinarily the above won't compile because 'foo' hasn't been 
declared but with opDispatch i can handle this. The problem is 
how do i handle different types of each property.

I was thinking about something like this:

class A
{
}

class B : A
{
}

class C : B
{
}

class T
{
     private Tuple[string] _properties;

     public this()
     {
         this.a = new A();
         this.b = new B();
         this.c = new C();
     }

     public void opDispatch(string name, T)(T element)
     {
         this._properties[name] = Tuple(T, element);
     }

     public auto opDispatch(string name)()
     {
         if (name in this._properties)
         {
             return 
cast(this._properties[name][0])this._properties[name][1];
         }
     }
}

Of course this doesn't compile but is this actually possible? 
i.e. storing the type and data. Then on retrieval returning the 
correct data cast to the correct type? All done dynamically 
without any property being pre-declared.