关于C#中泛型类型参数约束（where T : class）

.NET支持的类型参数约束有以下五种：

如下在WPF中获取当前窗体（或者用户控件）的父窗体，限定泛型必须为Class:

private void btnCancel_Click(object sender, RoutedEventArgs e)         {             Window hostWindow = GetParent<Window>(sender as Button);             if (hostWindow != null)             {                 hostWindow.Close();             }         }          public static T GetParent<T>(UIElement  uiElement) where T : class         {             T result;             var dp = LogicalTreeHelper.GetParent(uiElement);             result = dp as T;             while (result == null)             {                 dp = LogicalTreeHelper.GetParent(dp);                 result = dp as T;                 if (dp == null) return null;             }             return result;         }

原文：https://www.cnblogs.com/YzpJason/p/9358850.html