c# - NotifyOnPropertyChange实现

Question

如何实现NotifyOnPropertyChange方法？从继承者ViewModelBase调用它可以是:

NotifyOnPropertyChange (() => Property) 

该方法的输入将应用lambda表达式，该表达式指定需要通知的更改属性。

Answer 1

您的实现如下所示。它是使用System.Linq.Expressions命名空间实现的。

        protected void RaisePropertyChanged<T>(System.Linq.Expressions.Expression<Func<T>> lambda)
        {
            dynamic l = lambda.Body;
            string propertyName = l.Member.Name;
            OnPropertyChanged(propertyName);
        }

这是全类的一个例子。

    public class NotificationObject : INotifyPropertyChanged
    {
        private string _someProperty;

        public string SomeProperty
        {
            get { return _someProperty; }
            set
            {
                _country = value;
                RaisePropertyChanged(() => SomeProperty);
            }
        }

        public event PropertyChangedEventHandler PropertyChanged;

        protected virtual void OnPropertyChanged(string propertyName)
        {
            PropertyChangedEventHandler handler = PropertyChanged;
            if (handler != null) handler(this, new PropertyChangedEventArgs(propertyName));
        }



        protected void RaisePropertyChanged<T>(System.Linq.Expressions.Expression<Func<T>> lambda)
        {
            dynamic l = lambda.Body;
            string propertyName = l.Member.Name;
            OnPropertyChanged(propertyName);
        }
    }

不使用动态功能的完整实现如下所示:

        protected void RaisePropertyChanged<T>(System.Linq.Expressions.Expression<Func<T>> lambda)
        {
            if (lambda == null) throw new ArgumentNullException("lambda");

            var memberExpression = lambda.Body as MemberExpression;
            if (memberExpression == null) throw new ArgumentException("Invalid lambda expression.","lambda");

            var property = memberExpression.Member as PropertyInfo;
            if (property == null) throw new ArgumentException("Invalid lambda expression. Expression must be a property.", "lambda");

            // check if the property is not static
            var getMethod = property.GetGetMethod(true);
            if (getMethod.IsStatic) throw new ArgumentException("Invalid lambda expression. Property cannot be static.", "propertyExpression");

            string propertyName = memberExpression.Member.Name;
            OnPropertyChanged(propertyName);
        }