我如何将一个类作为参数传递，然后使用该类的共享方法？

Question

注意：这个问题不是问如何传递一个类的 instance。它询问如何传递具有共享项目的 类。

例如... 关于如何制作一个可以做到这一点的函数的任何想法？

Public Function InsertSQL(ByVal xClass As Type) As String
    InsertSQL = "Insert into "
    InsertSQL = InsertSQL & xClass.TableName
    InsertSQL = InsertSQL & " ("
    InsertSQL = InsertSQL & xClass.FieldList
    InsertSQL = InsertSQL & " )"
End Function

使用这样的一组类：

Public Class cClient
    Public Shared TableName = "Clients"
    Public Shared Function FieldList() As String
        FieldList = "Name, Phone"
    End Function
End Class

Public Class cSale
    Public Shared TableName = "Sales"
    Public Shared Function FieldList() As String
        FieldList = "Name, Amount"
    End Function
End Class

我在 Google 上搜索了“如何将类作为参数传递”，但没有找到任何可以访问类共享方法的方法。我只能得到认为我想要传递该类的实例的结果。

请注意，此代码只是一个示例。 而且 - 当然，如果我传递一个类的实例，我没有问题。
但是 - 这不是我想要弄清楚的。

Answer 1

我会在你的情况下使用Inheritance。 像这样的

Public Sub Main
    Dim c = new cClient()
    Dim sql = InsertSQL(c)
    Console.WriteLine(sql)
End Sub


' Pass an actual instance of a class that inehrits cTableBase'
' all of these classes have the same BASE functions and property
' defined in the base class
Public Function InsertSQL(ByVal xClass As cTableBase) As String
    InsertSQL = "Insert into "
    InsertSQL = InsertSQL & xClass.TableName
    InsertSQL = InsertSQL & " ("
    InsertSQL = InsertSQL & xClass.FieldList
    InsertSQL = InsertSQL & " )"
End Function

Public Class cTableBase
    Public TableName As String 
    Public Overridable Function FieldList() As String
    End Function
End Class

Public Class cClient 
    Inherits cTableBase
    Public Sub New
        TableName = "Clients"
    End Sub
    Public Overrides Function FieldList() As String
        FieldList = "Name, Phone"
    End Function
End Class

Public Class cSale 
    Inherits cTableBase
    Public Sub New
        TableName = "Sales"
    End Sub
    Public Overrides Function FieldList() As String
        FieldList = "Name, Amount"
    End Function
End Class

正如您在下面的评论中发布的那样。这可以通过使用反射传递给方法 InsertSQL 的类型来完成

Sub Main
    Dim c = new cClient()
    Dim result = InsertSQL(c.GetType())
    Console.WriteLine(result)
End Sub

Public Function InsertSQL(ByVal xClass As Type) As String

    Dim fi = xClass.GetField("TableName")
    Dim tableName = fi.GetValue(xClass)

    Dim mi = xClass.GetMethod("FieldList")
    Dim fieldList = mi.Invoke(xClass, Nothing)

    InsertSQL = "Insert into "
    InsertSQL = InsertSQL & tableName
    InsertSQL = InsertSQL & " ("
    InsertSQL = InsertSQL & fieldList
    InsertSQL = InsertSQL & " )"
End Function