How can I write a generic container class that implements a given interface in C#?

Question

Context: .NET 3.5, VS2008. I\'m not sure about the title of this question, so feel free to comment about the title, too :-)

Here\'s the scenario: I have several cla

Answer 1

You could subclass List<T> or some other collection class and use the where generic type constraint to limit the T type to be only IStartable classes.

class StartableList<T> : List<T>, IStartable where T : IStartable
{
    public StartableList(IEnumerable<T> arr)
        : base(arr)
    {
    }

    public void Start()
    {
        foreach (IStartable s in this)
        {
            s.Start();
        }
    }

    public void Stop()
    {
        foreach (IStartable s in this)
        {
            s.Stop();
        }
    }
}

You could also declare the class like this if you didn't want it to be a generic class requiring a type parameter.

public class StartableList : List<IStartable>, IStartable
{ ... }

Your sample usage code would then look something like this:

var arr = new IStartable[] { new Foo(), new Bar("wow") };
var mygroup = new StartableList<IStartable>(arr);
mygroup.Start(); // --> calls Foo's Start and Bar's Start