Question

In .NET 3.5 List<> gains a ForEach method. I notice this does not exist on IList<> or IEnumerable<> what was the thinking here? Is there another way to do this? Nice and simple short way to do this?

I ask because I was at a talk where the speaker said always use the more general interfaces.
But why would I use IList<> as a return type if I want to be able to turn around and use ForEach? Then I would just end up casting it back to a List<>.

Answer 1

what was the thinking here?

You can read Eric Lippert‘s blog for the reasons why this feature wasn’t added.

Is there another way to do this? Nice and simple short way to do this?

Why not just use the foreach keyword? I find it more readable.

foreach (var foo in ilist)
{
    // etc...
}

Though you can add a ForEach extension method to IEnumerable<T> if you want to:

public static void ForEach<T>(this IEnumerable<T> enumeration, Action<T> action)
{
    foreach (T item in enumeration)
    {
        action(item);
    }
}

Taken from here.