in reply to Re: Getting segfaults when destroying and recreating Tk box
in thread Getting segfaults when destroying and recreating Tk box

Thanks for your comment....
When I click the shutdown button the window closes and the following additional text is generated:
abort_routine Array_Index: 1
+abort_routine
abort_routine Array_Index: 1
-abort_routine
-abort_routine
-MAIN
I get a different series of responses than you....

Firstly when I run the code and the first box opens... 

+MAIN

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Then when I click on something in the first box... 
+do_button
do_button Array_Index: 1
-do_button
==MAIN - the first box has been closed

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Then in the last box, when I click on the "shutdown and close" button... 
+abort_routine
abort_routine Array_Index: 1
Segmentation fault

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Alternately, if I slimply click the close box, I instead see... 
Segmentation fault

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You see this is quite different from your response, ending in a segfault. But I notice you're using windows and I'm using Linux.

I'm running Fedora 7, perl -v says "This is perl, v5.8.8 built for x86_64-linux-thread-multi", the Tk rpm which is installed is tk-8.4.13-5.fc7.src.rpm from the livna rpm repository.

Is there any other info from me that would help work out what is going on?

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Re^3: Getting segfaults when destroying and recreating Tk box
by GrandFather (Saint) on Sep 05, 2007 at 03:02 UTC

    I suspect there is something nasty happening when you re-enter abort_routine. You could add:

    my $inAbort;

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    at the top of the script and change abort_routine to:

    sub abort_routine {
    return if $inAbort;
    
    $inAbort = 1;
    
    debug("+abort_routine");
    debug("abort_routine Array_Index: $Array_Index");

    # DO SOMETHING USEFUL HERE TO CLEAN UP THE PROCESS

    $MW->destroy();
    debug("-abort_routine");
}

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    so that abort_routine is not re-entered during the destroy or (probably better) change the button command to initiate a different sub that just performs $MW->destroy ();:

    ...

        $button = $MW->Button(
            -text    => "Shutdown and close",
            -command => [ \&do_close ] )->pack( -side => 'bottom' );

...

sub abort_routine {
    debug("+abort_routine");
    debug("abort_routine Array_Index: $Array_Index");

    # DO SOMETHING USEFUL HERE TO CLEAN UP THE PROCESS

    debug("-abort_routine");
}


sub do_close {
    $MW->destroy();
}

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    DWIM is Perl's answer to Gödel
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      Thanks again... I've followed your suggestions and learned something, but not solved the problem.

      If I use the original code (above) and simply remove the $MW->destroy() call from abort_routine, the segmentation fault disappears. Each time I click the button, the abort_routine gets called again, but of course without the $MW->destroy, the box never closes and the programme never exits.

      When I modify the abort_routine code to include the counter you suggested and test for non-zero at the outset, the segmentation fault still happens as soon as I try and destroy the box. Also, if I replace abort_routine with a do_close which contains only the $MW->destroy, I also get the segmentation fault.

      I've also tried using an alternate handle for the second box ($MW2), but I still get the segfault.

      It seems that its the second call to $MW->destroy that's doing the damage. Is there something I need to do to clean-up after the first call???

      Thanks,
      Stefan

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        I've sort of run out of ideas, especially as I've not actually seen the problem! However $mw->OnDestroy and Dialog Box may be of some help.

        DWIM is Perl's answer to Gödel
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