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Question

我试图让我的代码按照http://www.paulstovell.com/vb-anonymous-methods上的说明工作

到目前为止，我有包装：

Public Delegate Function PredicateWrapperDelegate(Of T, A)(ByVal item As T, ByVal argument As A) As Boolean
Public Class PredicateWrapper(Of T, A)
    Private _argument As A
    Private _wrapperDelegate As PredicateWrapperDelegate(Of T, A)

    Public Sub New(ByVal argument As A, _
         ByVal wrapperDelegate As PredicateWrapperDelegate(Of T, A))
        _argument = argument
        _wrapperDelegate = wrapperDelegate
    End Sub

    Private Function InnerPredicate(ByVal item As T) As Boolean
        Return _wrapperDelegate(item, _argument)
    End Function

    Public Shared Widening Operator CType( _
        ByVal wrapper As PredicateWrapper(Of T, A)) _
       As Predicate(Of T)
        Return New Predicate(Of T)(AddressOf wrapper.InnerPredicate)
    End Operator
End Class

然后我有了修改后的函数以使用我的部门 id 变量 (did)

 Function DidMatch(ByVal item As ListDataItem, ByVal did As Integer) As Boolean
        Return item.AssigneddepartmentID.Equals(did)
    End Function

然后我尝试从我的代码中调用它：

Dim children As List(Of String) = toplevel.FindAll(New PredicateWrapper(Of Integer, Integer)(Did, AddressOf DidMatch))

然后我在 DidMatch 上收到一个错误...错误方法“公共函数 DidMatch（项目作为 DeptMenuData，作为整数）作为布尔值”没有与委托“委托函数 PredicateWrapperDelegate（整数，整数）（项目作为整数）兼容的签名, 参数 As Integer) As Boolean'。

你能看到我做错了什么吗？

谢谢。

Answer 1

改变：

Dim children As List(Of String) = toplevel.FindAll(New PredicateWrapper(Of Integer, Integer)(Did, AddressOf DidMatch))

到：

Dim children As List(Of String) = toplevel.FindAll(New PredicateWrapper(Of ListDataItem, Integer)(Did, AddressOf DidMatch))