Q299491: FIX: Program Stops With Outstanding Class Reference

Article: Q299491
Product(s): Microsoft FoxPro
Version(s): 5.0,5.0a,6.0,7.0
Operating System(s): 
Keyword(s): kbOOP kbvfp500aBUG kbvfp500bug kbvfp600bug kbGrpDSFox kbCodeSnippet kbvfp700fixkbfixlis
Last Modified: 29-AUG-2001

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The information in this article applies to:

- Microsoft Visual FoxPro for Windows, versions 5.0, 5.0a, 6.0, 7.0 
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SYMPTOMS
========

Program A runs program B. Program B instantiates a programmatically defined
class, then exits. If program A attempts to COMPILE program B, the COMPILE
command fails and program execution stops, but no error is given in Visual
FoxPro (VFP) 5.0 or 6.0 when this occurs.

STATUS
======

This problem was corrected in Visual FoxPro version 7.0 for Windows.

In VFP 7.0, the following error message (error 1184) is given:

  File cannot be closed because outstanding references exist.

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

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

1. In VFP 5.0 or 6.0, paste the following code in a new program:

  CLEAR
  LOCAL lcOldConsole, lcOldSafety
  lcOldConsole = SET("CONSOLE")
  lcOldSafety = SET("SAFETY")
  SET CONSOLE OFF
  SET SAFETY OFF

  SET TEXTMERGE TO "MyTestProg.prg"
  TEXT
  	LOCAL loMyClass, lnRetVal
  	loMyClass = CREATEOBJECT("MyClass")
  	lnRetVal = loMyClass.TstProc()
  	RELEASE loMyClass
  	RETURN lnRetVal

  	DEFINE CLASS MyClass as Custom
  		PROCEDURE TstProc
  			RETURN 33
  		ENDPROC
  	ENDDEFINE
  ENDTEXT
  SET TEXTMERGE TO
  SET CONSOLE &lcOldConsole
  SET SAFETY &lcOldSafety

  COMPILE MyTestProg.prg

  SET PROCEDURE TO MyTestProg.prg
  ? SET("PROCEDURE")
  ? "Result: ", MyTestProg()

  *!* Program ends here if MyClass class is not cleared. There is no error given in VFP6.
  *!*	CLEAR CLASS MyClass  && Uncomment for VFP5/6 workaround.
  RELEASE PROCEDURE MyTestProg.prg
  COMPILE MyTestProg.prg

  ?  "This is the last line of code. It ran!"

2. Save and run this code (the program name is unimportant).

When the code runs in VFP 5.0 and 6.0, the output to the screen includes the
current PROCEDURE setting and "Result: 33" (that is, the return value from
MyTestProg.prg). The final line of code ("This is the last line...") is not
printed to _SCREEN. This is because an outstanding reference to MyClass exists,
so that the COMPILE MyTestProg.prg line does not run successfully. The program
exits without error and you may notice the message "Do Canceled" displayed on
the status bar.

In VFP7, when this code is run as-is, a new error message (error 1184) is given
on the "COMPILE..." line.

Uncomment the line that reads "Clear Class MyClass" to work around this in VFP
5.0, 6.0, and 7.0 and allow the COMPILE command to complete.

Additional query words:

======================================================================
Keywords          : kbOOP kbvfp500aBUG kbvfp500bug kbvfp600bug kbGrpDSFox kbCodeSnippet kbvfp700fix kbfixlist
Technology        : kbVFPsearch kbAudDeveloper kbVFP500 kbVFP600 kbVFP700 kbVFP500a
Version           : :5.0,5.0a,6.0,7.0
Issue type        : kbbug
Solution Type     : kbfix

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