Is it possible to compose two interfaces and duck type a class to the composition?

I have a class that inherits from ObservableCollection<T> to re-use the INotifyCollection functionality, but acts开发者_开发技巧 like a HashSet. I've called it ObservableHashSet<T>. I use both ObservableCollection and ObservableHashSet in my app.

I've reached a point where I want to pass either an ObservableCollection or an ObservableHashSet into a method, but the only functionality I'm interested in is IEnumerable<T> and INotifyCollectionChanged.

My question is: is it possible to have a single method that takes as its parameter either of these classes? i.e.

ObservableCollection<IExample> a = new ...
ObservableHashSet<IExample> b = new ...
MyMethod(a);
MyMethod(b);

I'm using .NET 4, in case there are any juicy features in there that are useful...

---

If you've inherited from ObservableCollection then using that as the parameter type should work.

---

I've found a nice solution, use a generic method and constrain the type parameter with the two interfaces I need:

public void MyMethod<T>(T collection) where T : IEnumerable<IExample>, INotifyCollectionChanged
{
}

This seems to do the trick nicely. I'd welcome any comments on doing it this way though :)