从共享（或静态）函数调用其他函数

Question

我收到此错误：Cannot refer to an instance member of a class from within a shared method or shared member initializer without an explicit instance of the class.

Partial Class _Default
    Inherits System.Web.UI.Page

    <WebMethod()> _
    Public Shared Function ParseData() As String
        Dim value as string = GetValue()
    End Function

    Private Function GetValue() as String
        Return "halp"
    End Function
End Class

我知道这与第一个函数是共享的，而第二个函数也应该是公共的这一事实有关，但我不完全理解其背后的原因。可能不相关，但我正在从一些 javascript 调用 web 方法。

Answer 1

Partial Class _Default
    Inherits System.Web.UI.Page

    <WebMethod()> _
    Public Shared Function ParseData() As String
        Dim value as string = GetValue()
    End Function

    Private Shared Function GetValue() as String
        Return "halp"
    End Function
End Class

或

Partial Class _Default
    Inherits System.Web.UI.Page

    <WebMethod()> _
    Public Function ParseData() As String
        Dim value as string = GetValue()
    End Function

    Private Function GetValue() as String
        Return "halp"
    End Function
End Class

如果必须共享，则使用第一个。如果您可以先初始化对象，或者如果您在同一个类中调用它，请使用第二个。

正如您所指出的，Web 方法必须是共享的（静态的）。在这种情况下，您从 webmethod 调用的方法也必须共享。

编辑：

另一种选择是为“GetValue”创建一个单独的类

Partial Class _Default
    Inherits System.Web.UI.Page

    <WebMethod()> _
    Public Shared Function ParseData() As String
        Dim util As Utilities = New Utilities
        Dim value as string = util.GetValue()
    End Function
End Class

Public Class Utilities  ''# Utilities is completely arbitrary, you can use whatever you like.
    Public Function GetValue() as String
        Return "halp"
    End Function
End Class