Return an empty IEnumerator

Question

I have an interface that, among other things, implements a "public IEnumerator GetEnumerator()" method, so I can use the interface in a foreach statement.

I implement this interface in several classes and in one of them, I want to return an empty IEnumerator. Right now I do this the following way:

public IEnumerator GetEnumerator() {     ArrayList arr = new ArrayList();     return arr.GetEnumerator(); } 

However I consider this an ugly hack, and I can't help but think that there is a better way of returning an empty IEnumerator. Is there?

Answer 1

This is simple in C# 2:

public IEnumerator GetEnumerator() {     yield break; } 

You need the yield break statement to force the compiler to treat it as an iterator block.

This will be less efficient than a "custom" empty iterator, but it's simpler code...

Answer 2

There is an extra function in the framework:

public static class Enumerable {     public static IEnumerable<TResult> Empty<TResult>(); } 

Using this you can write:

var emptyEnumerable = Enumerable.Empty<int>(); var emptyEnumerator = Enumerable.Empty<int>().GetEnumerator();