Why is my function not CLS-compliant?

Question

I'm getting the following warning message...

Return type of function 'ConnectionNew' is not CLS-compliant.

...for this function:

Public Function ConnectionNew(ByVal DataBaseName As String) As MySqlConnection
      Dim connection As MySqlConnection = Nothing
      connection = getConnection(DataBaseName())
      Return connection
End Function

What does this message mean, and how can I fix it?

Austin

What is MySqlConnection? Where is it defined? The error indicates that is the problem. – Billingsgate

MySqlConnection is a member of MySql.Data.MySqlClient. Am I not allowed to use that? – Austin

Of course you are allowed. But it is not an assembly that is CLS compliant. And as such, the only thing you can do is follow the answer from @Hans. – Billingsgate

Answer 1

It is because you are returning an object of a type that's not CLS compliant. Nothing you can do about that, you didn't write the type. Just acknowledge that you know that it isn't compliant, it isn't otherwise likely to cause any problems. Unless you use the function in another language that doesn't support all the .NET types. Fix:

<CLSCompliant(False)> _
Public Function ConnectionNew(ByVal DataBaseName As String) As MySqlConnection
   '' etc...
End Function

Viyella

Is that underscore deliberate, or a typo? Never mind, I see in a StructLayout "decoration" that it has the space and underscore appended, too, so it is now obvious to me that it was no typo. – Mcchesney

The underscore signifies a line continuation in VB, as if you'd written <CLSCompliant(False)> Public Function ConnectionNew ... (sorry to necromance) – Hudis