Limitations of VB 3.0 as a Client When Calling a VB 4.0 Server

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The Limitations

1. It is not possible to use early binding while creating object instances. This is because Visual Basic version 3.0 only supports late binding. In other words, the only way to create an object of type MyClass implemented by a server called MyServer is:

      Dim obj As Object
      Set Obj = CreateObject("MyServer.MyClass")
   						

2. You cannot call in-process OLE Servers (that is, Visual Basic version 4.0 OLE DLLs) from Visual Basic version 3.0. This is because you can only create 32-bit OLE DLLs in Visual Basic version 4.0.
3. You cannot return an array data type to Visual Basic version 3.0 from a Visual Basic version 4.0 OLE server because this is not supported in Visual Basic version 3.0.
4. Visual Basic version 3.0 does not support rich Error information like that provided by Visual Basic version 4.0's Error Object. So, if the server raises an error, only a default error message is returned back to the Visual Basic version 3.0 client. One way to work around this is to implement your own error object in the server, and have the Visual Basic version 3.0 client call that object in the error handler for the default error message.