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IEnumerable<T>.Each as C# Extension Method

February 11th, 2009 . by Daniel Hölbling

A very long time ago I went through the Ruby in 20 minutes tutorial when I saw this: 

@names.each do |name|
  puts "Hallo, #{name}!"
end

When C# came out later I always wondered why there is no functional equivalent on the IEnumerable<T> interface, since it would be a perfect place for quick inline method calls without having to write a full foreach statement.

At that time my knowledge of extension methods and delegates was too limited to do this myself, but that doesn’t mean it has to stay that way.

I finally remembered that I never got to it last time and implemented it today.

Oh and it’s so damn easy too:

public static class EachExtension
{
    public static void Each<T>(this IEnumerable<T> enumberable, Action<T> action)
    {
        foreach (var item in enumberable)
        {
            action(item);
        }
    }
}

To use this .Each method now you simply need to be using the Namespace where the EachExtension is in and you can write code like this:

IEnumerable<string> x = new[] {"hello", "world", "how", "are", "you"};
x.Each(Console.WriteLine);

Or with multiple parameters:

IEnumerable<string> x = new[] {"hello", "world", "how", "are", "you"};
x.Each(p => Console.WriteLine("{0}", p));

Or, even whole inline method bodies:

IEnumerable<string> x = new[] {"hello", "world", "how", "are", "you"};
x.Each(p =>
           {
               Console.Write("Word:");
               Console.WriteLine(p);
           });

So, Lambdas are fun after all :)

Posted in .NET, Coding | Comments


  • This is great...I was just going to send a note to the C# guys to suggest this. Each() is a fundamental expression in Ruby and Jquery, it should be part of C# if only to keep up with the trends. :)
  • Here's a tweak which returns the enumerable, which would allow chaining:

    public static IEnumerable Each<T>(this IEnumerable<T> enumberable, Action<T> action)
    {
    foreach (var item in enumberable) {
    action(item);
    }
    return enumberable;
    }
  • You could even extend this to allow for transformations like this:

    IEnumerable<string> x = new[] { "hello", "world", "how", "are", "you" };
    IEnumerable<int> enumerable = x.Each(p => p.Length);

    Code:

    public static IEnumerable<TOut> Each<T, TOut>(this IEnumerable<T> enumberable, Func<T, TOut> action)
    {
    foreach (var item in enumberable)
    {
    yield return action(item);
    }
    }
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