How to do a static cast in C#?

Question

Given a couple types like this:

interface I {}
class C : I {}

How can I do a static type cast? By this I mean: how can I change its type in a way that gets checked at compile time?

In C++ you can do static_cast<I*>(c). In C# the best I can do is create a temporary variable of the alternate type and try to assign it:

var c = new C();
I i = c;  // statically checked

But this prevents fluent programming. I have to create a new variable just to do the type check. So I've settled on something like this:

class C : I
{
    public I I { get { return this; } }
}

Now I can statically convert C to I by just calling c.I.

Is there a better way to do this in C#?

(In case anyone's wondering why I want to do this, it's because I use explicit interface implementations, and calling one of those from within another member function requires a cast to the interface type first, otherwise the compiler can't find the method.)

UPDATE

Another option I came up with is an object extension:

public static class ObjectExtensions
{
    [DebuggerStepThrough]
    public static T StaticTo<T>(this T o)
    {
        return o;
    }
}

So ((I)c).Doit() could also be c.StaticTo<I>().Doit(). Hmm...probably will still stick with the simple cast. Figured I'd post this other option anyway.

Answer 1

var c = new C(); 
I i = c;  // statically checked

equals to

I i = new C();

Answer 2

Simply cast it:

(I)c

Edit Example:

var c = new C();

((I)c).MethodOnI();

Answer 3

If you're really just looking for a way to see if an object implements a specific type, you should use as.

I i = whatever as i;
if (i == null) // It wasn't

Otherwise, you just cast it. (There aren't really multiple types of casting in .NET like there are in C++ -- unless you get deeper than most people need to, but then it's more about WeakReference and such things.)

I i = (I)c;

If you're just looking for a convenient way to turn anything implementing I into an I, then you could use an extension method or something similar.

public static I ToI(this I @this)
{
    return @this;
}