MVVM 中 ViewModelBase和 CommandBase

public class ViewModelBase : INotifyPropertyChanged , IDisposable  
    {
        public virtual string DisplayName { get; protected set; }  

        public event PropertyChangedEventHandler PropertyChanged;

        protected void OnPropertyChanged([CallerMemberName]string propertyName = null)
        {
            if (PropertyChanged != null)
            {
                PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
            }
        }

        public void Dispose()
        {
            this.OnDispose();
        }

        /// <summary>  
        /// 若支持IDisposable，请重写此方法，当被调用Dispose时会执行此方法。  
        /// </summary>  
        protected virtual void OnDispose()
        {

        }  
    }

 public class CommandBase : ICommand
    {
        private readonly Action<object> _command;
        private readonly Func<object, bool> _canExecute;

        public CommandBase(Action<object> command, Func<object, bool> canExecute)
        {
            if (command == null)
                throw new ArgumentNullException("command");
            _canExecute = canExecute;
            _command = command;  
        }

        public bool CanExecute(object parameter)
        {
            if (_canExecute == null)
                return true;
            return _canExecute(parameter); 
        }


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

        public void Execute(object parameter)
        {
            _command(parameter);  
        }
    }