What's the C# equivalent of @script ExecuteInEditMode() ?

What's the C# equivalent of the javascript @script ExecuteInEditMode() ?

Here is an example taken from one of my classes.

using UnityEngine;

[ExecuteInEditMode()]  
public class MyBehaviour : MonoBehaviour  
{  
    public void Update()  
    {  
        // Will run in edit mode.
    }  
}

You simply put:

[ExecuteInEditMode]

At the top of your script.