Question

我正在尝试将下面的2个例程转换为VB，我遇到了免费的Telerik转换器问题。它通常工作得非常好。

例程是C＃扩展例程，用于查找与递归地匹配特定类型的控件或控件的窗体控件：

   public static IEnumerable<T> FindAllChildrenByType<T>(this Control control)
   {
        var controls = control.Controls.Cast<Control>();
        var enumerable = controls as IList<Control> ?? controls.ToList();
        return enumerable
            .OfType<T>()
            .Concat<T>(enumerable.SelectMany(FindAllChildrenByType<T>));
    }

    public static T FindChildByType<T>(this Control control, String ctrlName)
    {
        foreach (var ctrl in from ctrl in FindAllChildrenByType<T>(control) let testControl = ctrl as Control where testControl != null && testControl.Name.ToUpperInvariant() == ctrlName.ToUpperInvariant() select ctrl)
        {
            return ctrl;
        }
        return default(T);
    }

我从Telerik网站获得的内容如下：

<System.Runtime.CompilerServices.Extension>
Public Function FindAllChildrenByType(Of T)(control As Control) As IEnumerable(Of T)
    Dim controls As Control() = control.Controls.Cast(Of Control)()
    Dim enumerable As IEnumerable = If(TryCast(controls, IList(Of Control)), controls.ToList())
    Return enumerable.OfType(Of T).Concat(enumerable.SelectMany(AddressOf FindAllChildrenByType(Of T)))
End Function

<System.Runtime.CompilerServices.Extension>
Public Function FindChildByType(Of T)(control As Control, ctrlName As String) As T
    For Each ctrl As T In From ctrl In FindAllChildrenByType(Of T)(control) Let testControl = TryCast(ctrl, Control) Where testControl IsNot Nothing AndAlso testControl.Name.ToUpperInvariant() = ctrlName.ToUpperInvariant() Select ctrl
        Return ctrl
    Next
    Return Nothing
End Function

这些例程在C＃中使用时效果很好，我需要及时回顾一下在VB中使用这些例程。

非常感谢！

Don B。

Answer 1

转换有两个问题：

它没有使用Option Infer On - VB相当于＆＃39; var＆＃39;是离开类型并使用Option Infer On。这是第一次方法转换的唯一问题。转换器试图猜测这些并弄错了 - 没有必要猜测 - 让Option Infer这样做。
第二种方法使用＆＃c; ctrl＆＃39;两次在同一范围内 - 不知道为什么C＃允许这样做。重命名＆＃39;外部＆＃39;对于每个变量。

更正的VB代码如下（注意扩展方法需要在＆＃39;模块中）：

Option Infer On

Module Test
    <System.Runtime.CompilerServices.Extension>
    Public Function FindAllChildrenByType(Of T)(control As Control) As IEnumerable(Of T)
        Dim controls = control.Controls.Cast(Of Control)()
        Dim enumerable = If(TryCast(controls, IList(Of Control)), controls.ToList())
        Return enumerable.OfType(Of T).Concat(enumerable.SelectMany(AddressOf FindAllChildrenByType(Of T)))
    End Function

    <System.Runtime.CompilerServices.Extension>
    Public Function FindChildByType(Of T)(control As Control, ctrlName As String) As T
        For Each ctrlx In From ctrl In FindAllChildrenByType(Of T)(control) Let testControl = TryCast(ctrl, Control) Where testControl IsNot Nothing AndAlso testControl.Name.ToUpperInvariant() = ctrlName.ToUpperInvariant() Select ctrl
            Return ctrlx
        Next
        Return Nothing
    End Function
End Module

使用LINQ将C＃代码转换为VB

1 个答案: