VB.NET: Is there a way to keep Nothing from defaulting to 0 for number types?
Pregunta
It's really bugging me that the VS 2010 IDE isn't barking at me for trying to pass Nothing through a method parameter that takes an user-defined enum. Instead, it's passing 0 through to the method. c# would never allow this. Is there some module-level modifier I can add like option strict
that will force the IDE to not allow these types of implicit conversions?
Solución
Sadly, no.
But you can assign values to your enumeration members while skipping 0
(or use a placeholder named None
or something like that), and at least handle this case at run time.
Sub Main
MyMethod(Nothing) ' throws Exception
End Sub
Sub MyMethod(e as MyEnum)
If e = 0 Then
Throw New Exception
End If
End Sub
Enum MyEnum
a=1
b=2
c=3
End Enum
Otros consejos
Nothing is the equivalent of default in the C# language. So no.
Reconsider your programming style, Nothing should be used very sparingly. Basically only in generic code, same place you'd use default in C#. You don't need it anywhere else, VB.NET doesn't insist on variable initialization like C# does. Any variable of a reference type gets initialized to Nothing automatically. Cringe-worthy to a C# programmer perhaps, but entirely idiomatic in VB.NET code.