In C#, the interface can be instantiated?

Question

I\'m reading the code in here. I find that private ITreeModel _model; in TreeList.cs:

namespace Aga.Controls.Tree
{
    public class TreeList: L         


        

Answer 1

It's implemented somewhere else in the code. If you call _model.GetType().ToString() you will see it is not just an interface.

But to answer your question correctly, YES, an interface can be instantiated. Some of you may think "no it can't", but it can be done (with some COM hacks):

class Foo : IFoo
{
    readonly string name;
    public Foo(string name)
    {
        this.name = name;
    }
    string IFoo.Message
    {
        get
        {
            return "Hello from " + name;
        }
    }
}
// these attributes make it work
// (the guid is purely random)
[ComImport, CoClass(typeof(Foo))]
[Guid("d60908eb-fd5a-4d3c-9392-8646fcd1edce")]
interface IFoo
{
    string Message {get;}
}
//and then somewhere else:
IFoo foo = new IFoo(); //no errors!

Here is my source.