Microsoft KB Archive/255683
Article ID: 255683
Article Last Modified on 8/27/2002
- Microsoft Visual FoxPro 6.0 Professional Edition
This article was previously published under Q255683
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:
Trying to call a Visual FoxPro COM server from Visual Basic using the Visual Basic GETOBJECT() function also results in an error message.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed at the beginning of this article.
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.
Keywords: kbbug kbcodesnippet kbpending KB255683