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 :)