BUG: Object References Might Not Be Released Properly

ID: Q190067

The information in this article applies to:

Microsoft Visual Basic Learning, Professional, and Enterprise Editions for Windows, version 6.0

SYMPTOMS

If a function call to an object returns a Variant and the Variant is not assigned to a local variable, Visual Basic might not dereference the object correctly. As a result, a new thread is created in the object's process space each time the function is called.

RESOLUTION

Assign the function's return value to a local variable, regardless of whether or not it is needed.

Example

The class clsMyObject has a function called MyVariantFunction that returns a Variant:


   Public Function MyVariantFunction() As Variant

If the return result of the function is not needed, calling the function without assigning the return value might cause new threads to be created:


   Public Sub TestFunction()
      clsMyObject.MyVariantFunction
   End Sub

To avoid the unnecessary creation of threads, assign the function's return value to a local variable, regardless of whether or not it is needed:


   Public Sub TestFunction()
      Dim vReturnValue As Variant

      ' Although this will not be used, it guarantees proper dereferencing.
      vReturnValue = clsMyObject.MyVariantFunction
   End Sub

STATUS

Microsoft has confirmed this to be a bug in the Microsoft products listed at the beginning of this article. We are researching this bug and will post new information here in the Microsoft Knowledge Base as it becomes available.

MORE INFORMATION

This type of behavior usually occurs when returning variant arrays that contain user-defined types.

Keywords : kbnokeyword kbNTOS kbVBp600bug kbWinOS kbGrpVB
Version : WINDOWS:6.0;
Platform : WINDOWS
Issue type : kbbug