从共享（或静态）函数调用等功能

Question

我得到这个错误：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 

我知道它是与第一功能是共享的，第二个函数大概应该是这样的事实公众也是如此，但我不完全理解它背后的原因。可能不相关，但我从一些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 

如果它必须是共享的，则与第一个去。如果你可以先初始化对象，或者如果你是从同一个类中调用它的话，那就去第二个。

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

编辑：

另一种选择是创建一个单独的类“的GetValue”

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