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Q314849: FIX: Parameters Passed as Empty Placeholders Default to NULL

Article: Q314849
Product(s): Microsoft FoxPro
Version(s): 7.0
Operating System(s): 
Keyword(s): kbCOMt kbGrpDSFox kbDSupport kbCodeSnippet kbvfp700 _IK283
Last Modified: 18-FEB-2002

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The information in this article applies to:

- Microsoft Visual FoxPro for Windows, version 7.0 
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SYMPTOMS
========

When you pass a parameter as an empty placeholder to a COM object from Visual
FoxPro (VFP) 7.0, the placeholder defaults to a value of NULL (rather than .F.
as in earlier versions of VFP).

RESOLUTION
==========

To resolve this problem, obtain the latest service pack for Visual FoxPro for
Windows 7.0. For additional information, please see the following article in the
Microsoft Knowledge Base:

  Q316964 How to Obtain the Latest Visual FoxPro for Windows 7.0 Service Pack

STATUS
======

Microsoft has confirmed this to be a problem in Microsoft Visual FoxPro for
Windows 7.0. This problem was first corrected in Visual FoxPro for Windows 7.0
Service Pack 1.

MORE INFORMATION
================

Steps to Reproduce Behavior
---------------------------

1. Create a new folder on your hard disk.

2. Copy the VFP 7.0 run-time files Vfp7r.dll and Vfp7enu.dll to the new folder.
  The version number of these files should be 9262.

3. Paste the following code in a new program (.prg) file and then save the file
  in the folder that you created in step 1:

  CD JUSTPATH(SYS(16))
  LOCAL lcDLLStr AS STRING, ;
  	loMyDll AS OBJECT
  CLEAR

  TEXT TO lcDLLStr NOSHOW
  DEFINE CLASS SERVER AS SESSION OLEPUBLIC
  	PROCEDURE SomeMethod(p1, p2, p3)
  	   	RETURN p2
  	ENDPROC
  ENDDEFINE
  ENDTEXT

  STRTOFILE(lcDLLStr, "DLLMAIN.PRG", 0)
  CREATE PROJECT DLLMAIN NOWAIT
  _VFP.ACTIVEPROJECT.FILES.ADD("DLLMAIN.PRG")
  _VFP.ACTIVEPROJECT.BUILD('DLLMAIN',4)
  _VFP.ACTIVEPROJECT.CLOSE

  loMyDll = CREATEOBJECT("DLLMAIN.SERVER")
  ? "With params like loMyDll.SomeMethod(.F.,,.F.), P2 =",loMyDll.somemethod(.F.,,.F.)
  RELEASE loMyDll

4. Run the code.

The COM DLL that is created by the sample code returns NULL for the second
parameter that it is passed. If you delete the run-time files from the folder
(causing the COM DLL to use the VFP 7.0 SP1 versions of these files) and then
rerun the sample code, the DLL will instead return .F. for the second parameter.

Additional query words: kbVFP700sp1fix

======================================================================
Keywords          : kbCOMt kbGrpDSFox kbDSupport kbCodeSnippet kbvfp700 _IK283 
Technology        : kbVFPsearch kbAudDeveloper kbVFP700
Version           : :7.0
Issue type        : kbbug
Solution Type     : kbfix

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