Question

我正在尝试实现一个中介辅助类，以便在视图模型之间传输信息。

从c＃

开始

static public class Mediator 
{ 
    static IDictionary<string, List<Action<object>>> pl_dict = new Dictionary<string, List<Action<object>>>(); 

    static public void Register(string token, Action<object> callback) 
    { 
        if (!pl_dict.ContainsKey(token)) 
        { 
            var list = new List<Action<object>>(); 
            list.Add(callback); 
            pl_dict.Add(token, list); 
        } 
        else 
        { 
            bool found = false; 
            foreach (var item in pl_dict[token]) 
                if (item.Method.ToString() == callback.Method.ToString()) 
                    found = true; 
            if (!found) 
                pl_dict[token].Add(callback); 
        } 
    } 

    static public void Unregister(string token, Action<object> callback) 
    { 
        if (pl_dict.ContainsKey(token)) 
            pl_dict[token].Remove(callback); 
    } 

    static public void NotifyColleagues(string token, object args) 
    { 
        if (pl_dict.ContainsKey(token)) 
            foreach (var callback in pl_dict[token]) 
                callback(args); 
    } 
}

我最终在vb中得到以下内容（由telerik＆＃39的在线转换器提供

Public NotInheritable Class Mediator
Private Sub New()
End Sub
Shared pl_dict As IDictionary(Of String, List(Of Action(Of Object))) = New Dictionary(Of String, List(Of Action(Of Object)))()

Public Shared Sub Register(token As String, callback As Action(Of Object))
    If Not pl_dict.ContainsKey(token) Then
        Dim list = New List(Of Action(Of Object))()
        list.Add(callback)
        pl_dict.Add(token, list)
    Else
        Dim found As Boolean = False
        For Each item As var In pl_dict(token)
            If item.Method.ToString() = callback.Method.ToString() Then
                found = True
            End If
        Next
        If Not found Then
            pl_dict(token).Add(callback)
        End If
    End If
End Sub

Public Shared Sub Unregister(token As String, callback As Action(Of Object))
    If pl_dict.ContainsKey(token) Then
        pl_dict(token).Remove(callback)
    End If
End Sub

Public Shared Sub NotifyColleagues(token As String, args As Object)
    If pl_dict.ContainsKey(token) Then
        For Each callback As var In pl_dict(token)
            callback(args)
        Next
    End If
End Sub
End Class

编译器不喜欢两个For Each＆lt; ...＆gt;作为var语句。我假设这是linq c＃风格，一直很难轻易翻译。这个表面上是因为我仍然试图理解整个原则。任何人都可以为这两条线提出适当的构造。

由于

Answer 1

在VB中，等效于var的目的是简单地声明变量而不指定类型，例如：

For Each callback In pl_dict(token)
    callback(args)
Next

但是，要使其正常工作，您需要Option Infer On。或者，您可以只指定迭代器变量的类型（实际上是Action(Of Object)），如下所示：

For Each callback As Action(Of Object) In pl_dict(token)
    callback(args)
Next

Vb.net中的Mediator Helper类

1 个答案: