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Clean up in case of quitting a task window

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  Clean up in case of quitting a task window Thomas Milius <Thomas-Milius@t-online.de> - 2011-11-29 21:02 +0100
    Re: Clean up in case of quitting a task window "David Holden" <SpamBin@apdl.co.uk> - 2011-11-29 20:51 +0000
    Re: Clean up in case of quitting a task window Rick Murray <heyrickmail-usenet@yahoo.co.uk> - 2011-11-30 07:58 +0100
      Re: Clean up in case of quitting a task window Thomas Milius <Thomas-Milius@t-online.de> - 2011-11-30 19:40 +0100

#1095 — Clean up in case of quitting a task window

I am running a BASIC program inside a task window. It is opening a couple
of files. I want to close these files in case that the Taskwindow is quit.
How can I achieve this?

ON ERROR doesn't seem to get aware of the quit. A complicated possibility
might be the installation of a wimp post filter written in assembler in BASIC
but this all complicated.

Many thanks in advance for any hints.

Best Regards

Thomas Milius

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#1097

On 29-Nov-2011, Thomas Milius <Thomas-Milius@t-online.de> wrote:

> I am running a BASIC program inside a task window. It is opening a couple
> of files. I want to close these files in case that the Taskwindow is quit.
> How can I achieve this?

I would suggest that you don't leave files open unless you're actually
accessing them. It's common practice to open a file and leave it open until
the program quits or it's completely finished with. If you open the file,
read/write the data, then immediately close the file the opportunities for
anything external to cause problems are minimal.

-- 
David Holden  -  APDL  -  <http://www.apdl.co.uk>

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#1102

On 29/11/2011 21:02, Thomas Milius wrote:

> I am running a BASIC program inside a task window. It is opening a couple
> of files. I want to close these files in case that the Taskwindow is quit.
> How can I achieve this?

You don't.

I'm not certain if, even, a C atexit() would work in this case?

Essentially TaskWindow allows non-multitasking programs to multitask. It 
is reasonable for a non-multitasking program to assume that something 
else isn't going to come along and quit it.

There doesn't appear, strangely enough, to be even a Service call for 
"TaskWindow_TaskDying" or somesuch.

So, your options:

   1. Only have files open as you actually need them. You'll need to look
      to see if you need to make some sort of locking mechanism (to block
      two different copies of your software working with the same file at
      the same time, risking one copy trashing data written by the other)

   2. Rewrite it as a proper multitasking program.
      [I'll admit, scrolling screen output is complicated, but there may
       be other ways around that, like a slidey-bar thing counting up
       progress instead of lines of output]


Best wishes,

Rick.

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#1112

In message <4ed5d431$0$5677$ba4acef3@reader.news.orange.fr>
          Rick Murray <heyrickmail-usenet@yahoo.co.uk> wrote:

> On 29/11/2011 21:02, Thomas Milius wrote:
> 
> > I am running a BASIC program inside a task window. It is opening a couple
> > of files. I want to close these files in case that the Taskwindow is
> > quit. How can I achieve this?
> 
> You don't.
> 
> I'm not certain if, even, a C atexit() would work in this case?
> 

I think a C-event would be launched so C atexit() would work, but yes the
program is in BASIC. It is a little program watching an USB Port for
asynchronous Messages and writing some results into a log file.

I have meanwhile searched around and in 2005 there was a similar thread.
Several people at that time suggested to claim the event handler of the
TaskWindow task. I shall try this. Of course I shall have to write some
line in assembler but I think only some lines.

Many thanks for the hints.

Best Regards

Thomas Milius

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