RelayCommand.cs

public class RelayCommand : RelayCommand<object>{
		public RelayCommand(Action<object> execute) : base(execute)
		{}

		public RelayCommand(Action execute) : base(execute)
		{}

		public RelayCommand(Action execute, Func<bool> canExecute) : base(execute, canExecute)
		{}

		public RelayCommand(Action<object> execute, Predicate<object> canExecute) : base(execute, canExecute)
		{}
	}

    public class RelayCommand<T> : ICommand
    {
        #region Fields

		private readonly Predicate<T> _canExecute;
		private readonly Action<T> _execute;

        #endregion // Fields

        #region Constructors

		public RelayCommand(Action<T> execute)
            : this(execute, null)
        { }

        public RelayCommand(Action execute)
            : this(o => execute())
        { }

        public RelayCommand(Action execute, Func<bool> canExecute)
            : this(o => execute(), o => canExecute())
        { }

		public RelayCommand(Action<T> execute, Predicate<T> canExecute)
        {
            if (execute == null)
                throw new ArgumentNullException("execute");

            _execute = execute;
            _canExecute = canExecute;
        }

        #endregion // Constructors

        #region ICommand Members

        [DebuggerStepThrough]
        public bool CanExecute(object parameter)
        {
			return _canExecute == null ? true : _canExecute((T)parameter);
        }

        public event EventHandler CanExecuteChanged
        {
            add { CommandManager.RequerySuggested += value; }
            remove { CommandManager.RequerySuggested -= value; }
        }

        public void Execute(object parameter)
        {
			_execute((T)parameter);
        }

        #endregion
    }