FIX: Servers Do Not Release if Init Returns .F.

• Microsoft Visual FoxPro for Windows, version 6.0

SYMPTOMS

The following rrors are received when you try to load a Visual FoxPro COM DLL or COM EXE.

In Visual FoxPro, the error is:

OLE error code 0x80004005: Unspecified error.

Run-time error '-2147467259(80004005)':
Automation error
Unspecified error

CAUSE

This is known to happen if the Visual FoxPro COM server's Init method returns False (.F.).

STATUS

Microsoft has confirmed this to be a bug in the Microsoft products listed at the beginning of this article.

This bug was corrected in Visual Studio 6.0 Service Pack 3. For more information about Visual Studio service packs, please see the following articles in the Microsoft Knowledge Base:

Q194022 INFO: Visual Studio 6.0 Service Packs, What, Where, Why

Q194295 HOWTO: Tell That Visual Studio 6.0 Service Packs Are Installed

MORE INFORMATION

This article helps you attempt to delete the Visual FoxPro COM DLL to test to see if there is a sharing violation. If there is, this is an indication that the COM DLL is loaded in memory.

Note that if you attempt to load COM DLL in Visual Basic 6.0, you can delete Visual FoxPro COM DLL. This is different than attempting to load Visual FoxPro COM DLL into Excel 97 VBA. In Excel 97 VBA, you cannot delete the COM DLL until Excel is closed. However, attempting to load a Visual FoxPro COM EXE in Visual Basic 6.0 leaves the VFP COM EXE running.

Steps to Reproduce Behavior

1. Place the following code into a new program file and save it as falseinit.prg:




   DEFINE CLASS falseinit AS custom OLEPUBLIC

        Name = "falseinit"

        PROCEDURE Init
           RETURN .F.
        ENDPROC

        PROCEDURE hello
           RETURN "Hello There"
        ENDPROC

        PROCEDURE ERROR()
           LPARAMETERS nError, cMethod, nLine
           errStr="ErrorNum: " + STR(nError) + ;
             "Method Name: " + cMethod + ;
             "On Line: " + STR(nLine) + ;
             "Message: " + MESSAGE()

           STRTOFILE(errStr,"c:\falseinit.txt",.T.)
           COMRETURNERROR(cMethod,errStr)
        ENDPROC

   ENDDEFINE
 

2. Add the program to a new project named falseinit.prg and build the project into a Visual FoxPro EXE.



3. Issue the following commands in the Visual FoxPro Command window to attempt to load the COM EXE and check the variable type:




ox=CreateObject("falseinit.falseinit")
? VARTYPE(ox) 

4. Press the ENTER key to run the first line of code above, and note that the "OLE error code 0x80004005: Unspecified error" is received. The VARTYPE() function should return "U," indicating that the ox variable does not contain an object reference.



5. Bring up the Windows NT Task Manager and go to the Processes tab. Falseinit.exe should be listed. End Process on it to unload the VFP COM EXE from memory.



6. The following code can be used in Visual Basic or Excel 97 Visual Basic for Applications to load the Visual FoxPro COM EXE built previously. It assumes that you have a working knowledge of Visual Basic or Visual Basic for Applications.




Sub VFPTest()

Dim ox As Object
Set ox = CreateObject("falseinit.falseinit")
Set ox = Nothing

End Sub
 

Note that there is an Error() method in the code for the VFP COM server. This code should write a file named "falseinit.txt" to the root of the C: drive and also should return information about the error. A search of the C: drive after trying to load the falseinit.exe unsuccessfully does not turn up the falseinit.txt file. This occurs because the Error() method is never run; the Init() method returns False and the COM server does not fully instantiate. This is the bug.

Additional query words:

Keywords : kbservicepack kbCOMt kbOOP kbVFp600 kbVFp600bug kbVS600sp2 kbVS600SP1 kbVS600sp3fix kbGrpFox
Version : WINDOWS:6.0
Platform : WINDOWS
Issue type : kbbug