Expression Blend 3 Help: The missing DelegateCommand class

Some tutorials from the Expression Blend 3 help docs (e.g. “Try it: Display data from a sample SQL database”, which is based on these two articles) require a class that is present in the ColorSwatch WPF sample. The problem is that someone appears to have forgotten to bundle the ColorSwatch sample with the Blend 3!

To save you the hassle of trying to track down the DelegateCommand class here it is:

using System; 
using System.Collections.Generic; 
using System.Text; 
using System.Windows.Input; 
 
namespace ColorSwatch 
{ 
    public sealed class DelegateCommand : ICommand 
    { 
        public delegate void SimpleEventHandler(); 
 
        private SimpleEventHandler handler; 
 
        private bool isEnabled = true; 
 
        public DelegateCommand(SimpleEventHandler handler) 
        { 
            this.handler = handler; 
        } 
 
        #region ICommand implementation 
 
        void ICommand.Execute(object arg) 
        { 
            this.handler(); 
        } 
 
        bool ICommand.CanExecute(object arg) 
        { 
            return this.IsEnabled; 
        } 
 
        public event EventHandler CanExecuteChanged; 
 
        #endregion 
 
        public bool IsEnabled 
        { 
            get { return this.isEnabled; } 
            set 
            { 
                this.isEnabled = value; 
                this.OnCanExecuteChanged(); 
            } 
        } 
 
        private void OnCanExecuteChanged() 
        { 
            if (this.CanExecuteChanged != null) 
            { 
                this.CanExecuteChanged(this, EventArgs.Empty); 
            } 
        } 
    } 
}