Why is .ForEach() on IList and not on IEnumerable? [duplicate]

Answer 1

Because ForEach(Action) existed before IEnumerable<T> existed.

Since it was not added with the other extension methods, one can assume that the C# designers felt it was a bad design and prefer the foreach construct.

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Edit:

If you want you can create your own extension method, it won't override the one for a List<T> but it will work for any other class which implements IEnumerable<T>.

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

Answer 2

It's called "Select" on IEnumerable<T> I am enlightened, thank you.

Answer 3

LINQ follows the pull-model and all its (extension) methods should return IEnumerable<T>, except for ToList(). The ToList() is there to end the pull-chain.

ForEach() is from the push-model world.

You can still write your own extension method to do this, as pointed out by Samuel.

Answer 4

Because ForEach() on an IEnumerable is just a normal for each loop like this:

for each T item in MyEnumerable
{
    // Action<T> goes here
}