System.Collections.Generic.List<T> ForEach method is missing in Windows 8 Runtime

It seems that the handy ForEach method has been removed from the List of T class in the WinRT. According to Wes Haggard of the .NET Framework Bas Class Library (BCL) Team:

“List<T>.ForEach has been removed in Metro style apps. While the method seems simple it has a number of potential problems when the list gets mutated by the method passed to ForEach. Instead it is recommended that you simply use a foreach loop.”

Which is a shame, as I use this method quite a bit to invoke method group calls to do one-time iterations over Lists, like this:

keywordResults.ForEach(this.searchActivity.Keywords.Add);

For situations like this, the mutation issue doesn’t arise and it would be safe to use the ForEach method if it existed. So I did an extension method implementation of the functionality by taking a look at the decompiled code of the method in earlier versions of the .NET Framework:

public void ForEach(Action<T> action)
{
  if (action == null)
    ThrowHelper.ThrowArgumentNullException(ExceptionArgument.match);
  for (int index = 0; index < this._size; ++index)
    action(this._items[index]);
}

Using this as a starting point it was fairly easy to come up with an extension method version:

public static void ForEach<T>(this IEnumerable<T> list, Action<T> action)
{
    if (action == null)
    {
        throw new ArgumentNullException("action");
    }

    foreach (var t in list)
    {
        action(t);
    }
}

Now I can use the extension to give me the same ForEach functionality on IEnumerable objects such as List<T> as I had before.