C#代表操作是如何用F#编写的？

Question

如何在C#中实现F#操作？

我在C#代码背后有以下代码：

public MainWindow()
        {
            InitializeComponent();
            ViewModel = new ViewModel();
            DataContext = ViewModel;
        }

        private void ListView_PreviewMouseLeftButtonUp(object _, MouseButtonEventArgs e)
        {
            _closeAdorner();
        
            // listView here equals object _  
            var listView = (ListView)e.Source;
            var grid = (Grid)listView.Parent;
            var selecteditem = (InnerRow)listView.SelectedItem;
            ViewModel.Visit = selecteditem;
            ViewModel.LastName = selecteditem.LastName;
        
            var adornerLayer = AdornerLayer.GetAdornerLayer(grid);
            if (adornerLayer == null)
                throw new ArgumentException("datagrid does not have have an adorner layer");

            var adorner = new DataGridAnnotationAdorner(grid);
            adornerLayer.Add(adorner);
        
           _closeAdorner = () => adornerLayer.Remove(adorner);
        }

我正在尝试将其转换为F#：

let handlePreviewMouseLeftButtonUp (obj: obj) (a, c) =
      let e = (obj :?> MouseButtonEventArgs)
      let listView = e.Source :?> ListView   // This is the ListView control that was clicked.
      let grid = listView.Parent :?> Grid
          
      let selectedItem = c.InnerRows |> List.filter (fun r -> Some r.Id = c.SelectedInnerRow) |> List.head
    
      let adorner = DataGridAdorner(grid)

      let installAdorner =
        let adornerLayer = AdornerLayer.GetAdornerLayer(grid)
        if (adornerLayer.GetAdorners = []) then adornerLayer.Add(adorner) else adornerLayer.Remove(adorner)

最后一行: if (adornerLayer.GetAdorners = [])，然后adornerLayer.Add(装饰品)adornerLayer.Remove(装饰器)

显然不编译，也不正确。如何将C# _closeAdorner编写成在F#中具有相同的函数？

谢谢。

提亚

Answer 1

我不知道_closeAdorner、InnerRow、DataGridAdorner和其他元素是什么。无论如何，这里我修复了代码中的一些语法问题(不是全部)：

let handlePreviewMouseLeftButtonUp(obj : obj) (e:MouseButtonEventArgs)  =
    let listView = e.Source        :?> ListView   // This is the ListView control that was clicked.
    let grid     = listView.Parent :?> Grid
        
    let selectedItem = listView.SelectedItem :?> InnerRow//  |> List.filter (fun r -> Some r.Id = c.SelectedInnerRow) |> List.head
    
    let adorner = DataGridAdorner(grid)

    let installAdorner =
        let adornerLayer = AdornerLayer.GetAdornerLayer(grid)
        if adornerLayer.GetAdorners(grid) = [||] then adornerLayer.Add(adorner) else adornerLayer.Remove(adorner)
    ()

在构造函数中，可以添加如下所示的事件处理程序：

listView.MouseUp.AddHandler(MouseButtonEventHandler(handlePreviewMouseLeftButtonUp))

您还可以删除它：

listView.MouseUp.RemoveHandler(MouseButtonEventHandler(handlePreviewMouseLeftButtonUp))

要创建通用Action，您可以这样做：

let action = Action<_,_>(handlePreviewMouseLeftButtonUp)

其中，<_,_>对应于操作接收的参数数。