Visual Basic® 2010 Unleashed

The IEnumerable Interface

You implement the IEnumerable interface each time you want your class to support For..Each loops. Each time you iterate an object (typically a collection) using For Each, it is because that object implements IEnumerable. The .NET Framework offers lots of collections (including generic ones) and enables creating custom collections inheriting from built-in ones; therefore, implementing IEnumerable will probably be spared for you. It’s important to understand how the interface works, especially for its intensive usage when working with LINQ. IEnumerable provides one method, named GetEnumerator, which generally is implemented as follows:

As you can see, the method returns the result of the conversion of the class instance ...