merge 2 classes into one class at runtime

Suppose I have Class A with some properties and Attributes, and Class B with the same, how can I merge these 2 class Properties and properties Attributes into 1 class at runtime, or better is how can I add these 2 classes into a a third class as properties of this new class with their Fields, Properties, Methods, etc... at Runtime ?

Using reflection or the News .NET 4.0 Dynamic or expando Object

Edit: Damn I am sorry to all for not being clear, what I want is to create a dynamic ViewMo开发者_StackOverflow中文版del for MVC, where other classes are in some other assemblies, and I want them to be part of the model with their Datavalidation attributes. and I don't know how many or what exactly these classes are gonna be, so I want to iterate through assemblies and choose them then add them to the main View Model.

You can't change a type at runtime. Expando might be an option, but I am not clear how you want to interact with this object, as you would seem to be limited to reflection, and expando is not a huge friend of reflection.

It might help to clarify your requirement here, but IMO you might do better to consider loading (at runtime) a property-bag based on reflection from the two inputs; something like a Dictionary<string,object> which would let you map named keys to values.

One other thing that might be what you are after here is partial classes, but this is a single type spread over multiple source files:

partial class Foo {
    private string bar;
}
partial class Foo {
    public string Bar { get {return bar;} set {bar = value;} }
}

A final option here is TypeBuilder, but that is massive overkill in most scenarios.

Assuming you don't have access to the code for either of the classes (otherwise you could just merge the code), you can create a wrapper that aggregates the two classes with the combined interfaces:

public class AandB
{
  private ClassA _instanceA = new ClassA();
  private ClassB _instanceB = new ClassB();

  public bool PropertyA
  {
    get
    {
      return _instanceA.PropertyA;
    }
    set
    {
      _instanceA.PropertyA = value;
    }
  }

  public bool PropertyB
  {
    get
    {
      return _instanceB.PropertyB;
    }
    set
    {
      _instanceB.PropertyB = value;
    }
  }
}