Question

"cannot quit visual foxpro"

Asked by: mjacobs2929

I know about issuing  "ON SHUTDOWN CLEAR EVENTS" before "READ EVENTS" and I know about reissuing "ON SHUTDOWN" in your exit routine etc etc. And I've got a system which works exactly as I expect it to while I'm still in the VFP environment. I can deliberately cause an untrapped error and the program will shut itself down. However, as soon as I turn that into a standalone executable, the same error will produce the dreaded "cannot quit visual foxpro" and it's driving me mad!

The only clue I'm getting is that the refusal to quit seems to be tied up with native class Form Release code. (I've eliminated the possibility that it's my own code by only running that "if not quitting" (and the variable "quitting" exists))

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Asked On
2009-08-18 at 09:08:09ID24661916
Tags

visual foxpro

Topic

FoxPro Database

Participating Experts
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Answers

 

by: jrbbldrPosted on 2009-08-18 at 09:49:33ID: 25125168

Many times this problem is caused by a Modal form being open when the shutdown is attempted.

If that is the case, then you need to make certain that your Shutdown closes all forms.

Good Luck


 

by: pcelbaPosted on 2009-08-18 at 10:55:34ID: 25125779

You can try:

ON SHUTDOWN EXECSCRIPT([on shutdown]+CHR(13)+[on error *]+CHR(13)+[clear events]+CHR(13)+[release all]+CHR(13)+[quit])

 

by: mjacobs2929Posted on 2009-08-18 at 12:54:49ID: 25126920

pcelba: I don't quite see what you're aiming for.  Your "script" woudl run (a subset of) what is already in my exit routine - which runs already.

jrbblda - that's a very interesting point. I hadn't considered the Modality of the forms. You're probably on the right track. The obvious question, however, is how the hell do I force them to close?

My exit routine already tries to close any open forms with a standard loop

FOR each oFrm in _SCREEN.Forms
      oFrm.abandoned=.t.
      quitting=.t.
      oFrm.Release()
ENDFOR

(I use the two variables to make the forms skip code that I don't want to run if I'm quitting and, yes, I've tried it with and without them and different combinations)

I even thought of including "Thisform.windowtype=0" as a line in the class release code but that isn't permitted (gives an error "WINDOWTYPE IS READ ONLY" at run time.

So how else can we force a modal window to shut?

 

by: CaptainCyrilPosted on 2009-08-18 at 13:20:55ID: 25127220

RELEASE ALL
CLEAR ALL
ON SHUTDOWN
CLEAR EVENTS

 

by: pcelbaPosted on 2009-08-18 at 13:24:59ID: 25127277

The script should close all modal forms.

 

by: Olaf_DoschkePosted on 2009-08-18 at 13:48:04ID: 25127515

Rather do ON SHUTDOWN QUIT instead of any more or less fancy script or procedure making any attempts to clear things.

Bye, Olaf.

 

by: pcelbaPosted on 2009-08-18 at 13:53:47ID: 25127567

But ON SHUTDOWN QUIT does not work when modal form exists.

 

by: pcelbaPosted on 2009-08-18 at 13:56:26ID: 25127590

It seems I am wrong... Sorry

 

by: Olaf_DoschkePosted on 2009-08-18 at 15:18:27ID: 25128193

Don't worry. I've had this and other worries about a simple QUIT. But in fact it's "stronger" than CLEAR EVENTS and also gives you the chance to do more, as it does release all forms, you run through all the events, eg QueryUnload(). It still has problems with a Messagebox() though, IIRC, but there's little you can do about that.

Bye, Olaf.

 

by: tusharkanvindePosted on 2009-08-18 at 21:45:28ID: 25129661

Is quitting a public variable?

 

by: CaptainCyrilPosted on 2009-08-18 at 22:44:13ID: 25129862

What I would do is have  cleanup procedure.

It closes everything with TRY CATCH just in case it could not and at the end of it I have a QUIT command.

 

by: Olaf_DoschkePosted on 2009-08-18 at 23:50:04ID: 25130118

Hi Tushar,

QUIT does also clear variables in the end, it also closes databases, connections. There are things holding a quit: Messagebox as said, and open transactions. Even ON ERROR * does not suppress the error message. Another reason to handle transactions correctly and as short as possible. You can DO WHILE TXNLEVEL()>0 ROLLBACK ENDDO before QUIT.

QUIT also does not quit immediately, it does cause forms to close and triggers QueryUnload()s. If you have good tidy up code in destroy events of classes and queryunload, unload and destroy of forms, then QUIT does it's job very well.

Cyril,
I don't see that a cleanup procedure can really do more than that. If you finally QUIT after first trying to do what QUIT also does, then you don't gain anything.

Remarks on QUIT in the help:
Always use QUIT to terminate a Visual FoxPro session. If you turn the computer off without issuing QUIT, open files might become damaged and data lost, and temporary work files that would normally be deleted may be left on disk.

One thing you can do additionally in a cleanup or exit procedure is Killprocess, that is, if you get to the line after QUIT. When you use a cleanup procedure, make sure you have it within the main.prg, where it's always on the program stack and therefore can't be "forgotten". Prevent modal states through Messageboxes without timeout. I think print previews can also be a stopper.

Bye, Olaf.

 

by: CaptainCyrilPosted on 2009-08-18 at 23:53:12ID: 25130135

I do a cleanup because my software have Excel, PowerPoint, Word, Outlook, MSProject or any other software open. So I make sure they are closed and the files are either saved or properly gotten rid off. I also clean up the temp directory.

 

by: Olaf_DoschkePosted on 2009-08-20 at 00:11:33ID: 25139891

Cryl, okay, QUIT would also destroy references to office and other OLE servers, but itself would not handle any tidy up in them. Still, as I already said twice QUIT does not QUIT directly, it triggers QueryUnload() of forms and Destroy of objects. So these tasks would then need to be part of the classes you have handling office.

You don't need  a cleanup routine as QUIT already triggers all clean up routines in all class instances running. The proof is below.

o = CreateObject("quitcustom")
Quit 
Define Class quitcustom as custom
   Procedure destroy()
      MessageBox("bye")
   EndProc 
EndDefine 
                                              
1:
2:
3:
4:
5:
6:
7:

Select allOpen in new window

 

by: mjacobs2929Posted on 2009-08-23 at 05:09:15ID: 25162306

I have solved the problem.

None of the discussion above was directly relevant. I'm already doing the transaction testing and rollbacks, the try catch endtrys, the clear events, the on shutdown (various). NONE had the slightest effect. But I'm inclined to award the points to jrbbldr who - by mentioning the modal forms - forced me to look in the right places.

By a process of elimination I found two guilty parties. Both objects I included in my standard FORM class. One is the cryptpak component which allows me to use encryption and hashing throughout my applications. This is an activex component which we can't modify. Closing forms with it normally presents no problems but when it's on a bunch of forms you're trying to close in an errortrapping situation, it somehow becomes a "dangling object" and simply will not let go. I solved that problem by removing it from the form class and declaring it as a universal object at the beginning of my apps. That way it only needs a single release and stops causing problems.

The other was the microsoft timer object, which I also include in my standard form class. That too caused a problem IF THE TIMER WAS STILL ACTIVE when you tried to force a shutdown. The solution here was to explicitly disable the timer as part of the standard form release code.

20120131-EE-VQP-002

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