LINQ's ForEach doesn't work on IEnumerable<T>

Sun, 2009-03-29 09:39 — roger

For some reason, LINQ's ForEach extension method doesn't work on IEnumerable<T>; it only works on IList<T>. Easy fix:

public static class EnumerableExtensions
{
    public static void ForEach<T>(this IEnumerable<T> values, Action<T> action)
    {
        foreach (var value in values)
        {
            action(value);
        }
    }
}

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Comments

Sat, 2009-11-28 18:46 — daniel newman (not verified)

so we implement the enumerable interface with Link in such a way

Why would we need to?

Lets say i have a list of rectangle objects i need to enumerate through via foreach. so we implement the enumerable interface with Link in such a way using List<T>.

    public class RectangleStartingPoints<T> : IEnumerable<T>
    {

        List<T> _items = new List<T>();

        public void Add(T item)
        {
            _items.Add(item);
            
        }

        public IEnumerator<T> GetEnumerator()
        {
            foreach (T item in _items)
            {
                yield return item;
            }
        }

        System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator()
        {
            return this.GetEnumerator();
        }

    }

since we've implemented using List<T> we can foreach all we want. or maybe i missed something?

Sun, 2009-11-29 13:15 — roger

Yeah, you did

This isn't about implementing the collection. It's about doing something with it. It's the difference between:

foreach (var user in users.Where(x=>x.Name == "Roger"))
    drinks.Invite(user);

...and...

users.Where(x=>x.Name == "Roger").ForEach(user => drinks.Invite(user));

Admittedly, it's not a huge difference, and Eric Lippert doesn't like it, but it does come in useful for some things.

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