Explicitly use extension method

Question

I'm having a List<T> and want get the values back in reverse order. What I don't want is to reverse the list itself.

This seems like no problem at all since there's a Reverse() extension method for IEnumerable<T> which does exactly what I want.

My problem is, that there's also a Reverse() method for List<T> which reverses the list itself and returns void.

I know there are plenty of ways to traverse the list in reverse order but my question is:

How do I tell the compiler that I want to use the extension method with the same name?

var list = new List<int>(new [] {1, 2, 3});
DumpList(list.Reverse());                   // error

Answer 1

The best way to explictly bind to a particular extension method is to call it using shared method syntax. In your case, you would do that like:

DumpList(Enumerable.Reverse(list));

The problem with some of the other approaches mentioned here is that they won't always do what you want. For example, casting the list like so:

((IEnumerable)list).Reverse()

could end up calling a completely different method depending on the namespaces you have imported, or what type the calling code is defined in.

The only way to be 100% sure you bind to a particular extension method is to use the shared method syntax.

Answer 2

var list = new List<int>(new [] {1, 2, 3});
DumpList((list as IEnumerable<int>).Reverse());

OR

IEnumerable<int> list = new List<int>(new [] {1, 2, 3});
DumpList(list.Reverse());