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Q255683: BUG: The GETOBJECT() Function Fails When Calling a Visual FoxPro

Article: Q255683
Product(s): Microsoft FoxPro
Version(s): 6.0
Operating System(s): 
Keyword(s): kbCOMt kbvfp600 kbGrpDSFox kbDSupport kbCodeSnippet
Last Modified: 17-MAY-2002

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The information in this article applies to:

- Microsoft Visual FoxPro for Windows, version 6.0 
-------------------------------------------------------------------------------

SYMPTOMS
========

The GETOBJECT() function in Visual FoxPro activates an Automation object and
creates a reference to the object. If the application is already running, you
can prevent additional instances of the application from starting by omitting
FileName and including ClassName, as in this example:

  oleApp = GETOBJECT(, "Excel.Application")

This type of approach is also useful when you want to share Component Object
Model (COM) objects between applications, sharing the object's properties,
events, or methods (PEMs). For instance, a Microsoft Visual Basic application
and a Microsoft Visual C++ application could exchange and share data via
separate connections to the same instance of Microsoft Excel.

While Visual FoxPro allows you to create a COM server, the GETOBJECT() function
cannot be used to instantiate it. The command fails with the following error
message when you try:

  OLE error code 0x800401e3: Operation unavailable.

Trying to call a Visual FoxPro COM server from Visual Basic using the Visual
Basic GETOBJECT() function also results in an error message.

STATUS
======

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

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

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

To demonstrate this problem, save the following code to a new program in Visual
FoxPro 6.0 and run it. Please close any open projects, designers, and so forth,
before doing so. The program programmatically creates and builds a Visual FoxPro
COM .exe file. It then attempts to instantiate it using the GETOBJECT()
function.

  **********
  * Start sample code to reproduce GETOBJECT() problem calling VFP COM .exe
  *
  *
  LOCAL lnFileHand, lnBuildSuccess, lcOldConsole, lcOldSafety
  SET DEFAULT TO JUSTPATH(SYS(16))
  *!* Clean up any project files/program files from any previous runs.
  DELETE FILE GETFOXCOM.*
  *!* Retain environmental settings for later restoration.
  lcOldConsole = SET('CONSOLE')
  SET CONSOLE OFF
  lcOldSafety = SET('SAFETY')
  SET SAFETY OFF

  *!* Create the main program with the class definition of the COM server.
  SET TEXTMERGE TO 'GETFOXCOM.PRG'
  TEXT
  	DEFINE CLASS myserver AS CUSTOM OLEPUBLIC
  		HEIGHT = 69
  		WIDTH = 172
  		NAME = "myserver"
  		NEWPROP = 1
  	ENDDEFINE
  ENDTEXT
  SET TEXTMERGE TO

  *!* Create a project for the server.
  CREATE PROJECT GETFOXCOM NOWAIT
  *!* Add the main program.
  _VFP.ACTIVEPROJECT.FILES.ADD('GETFOXCOM.PRG')
  *!* Clean up the project.
  _VFP.ACTIVEPROJECT.CLEANUP()
  *!* Build a multi-instantiating (default COM .exe), looking for build success.
  lnBuildSuccess = _VFP.ACTIVEPROJECT.BUILD("GETFOXCOM",3,.T.,.T.)

  IF ! lnBuildSuccess	&& Build failed
  	WAIT WINDOW "Build Errors"
  	RETURN .F.
  ENDIF

  *!* Build success. Test GETOBJECT() on the server.
  WAIT WINDOW "COM server GETFOXCOM.MYSERVER built successfully" + CHR(13) + ;
  	"Press Any key to attempt GETOBJECT(, 'GETFOXCOM.MYSERVER')" + CHR(13) + CHR(13) +;
  	"Click 'IGNORE' on the error to finish the demo."

  *!* The GETOBJECT() call here should produce error message:
  *!* " OLE error code 0x800401e3: Operation unavailable"
  oVFPServer1 = CREATEOBJECT("GETFOXCOM.MYSERVER")
  oVFPServer2 = GETOBJECT(, "GETFOXCOM.MYSERVER")

  *!* Restore environmental settings.
  SET CONSOLE &lcOldConsole
  SET SAFETY &lcOldSafety
  *
  *
  ******* END CODE ****************

(c) Microsoft Corporation 2000, All Rights Reserved. Contributions by Trevor
Hancock, Microsoft Corporation.


Additional query words:

======================================================================
Keywords          : kbCOMt kbvfp600 kbGrpDSFox kbDSupport kbCodeSnippet 
Technology        : kbVFPsearch kbAudDeveloper kbVFP600
Version           : :6.0
Issue type        : kbbug
Solution Type     : kbpending

=============================================================================

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