Re: [Pythondialog-users] Catching errors in a dialog window

[Florent R. <f.r...@fr...>]

Hi,

Paraic OCeallaigh <par...@gm...> wrote:

> I have a fully working script but in the interest of catching something
> unexpected, I would like to catch any errors in the script itself and have
> it displayed in a infobox or similar, allowing the user to click OK and
> continue.
> Right now any errors I generate crash the script and are echoed to the
> command prompt. This is not desired as the script is a login menu which
> should not allow access to the shell. All others methods of getting to the
> shell have bee captured except these errors.

The normal approach would be something like:

  d = ...               # setup your Dialog instance

  try:
      all_the_rest()
  except:               # should be the same as "except BaseException:"
      d.msgbox(...)

This will even catch KeyboardInterrupt (generated when the Python script
receives SIGINT, typically when using Ctrl-C---but maybe dialog gets it
instead of python in this particular case, this is worth a little
check). If you don't want that, you can use "except Exception:" instead
of "except:". If you want to print some details about the problem, you
could catch the exception with "except BaseException as e:" or "except
Exception as e:" and use str(e) or something similar in the message to
be printed.

Of course, there are some kinds of error conditions that are likely to
prevent the script from printing the msgbox (e.g., if someone uninstalls
dialog while the script is running; hard disk corruption preventing
correct execution of dialog or Python; MemoryError...). It's a bit as if
taking "all" precautions not to fall when walking. Should an earthquake
start right under your feet, it would be difficult not to fall
nevertheless...

Regards


P.S.: if you really use your script as a login shell, I'm a bit
      surprised that you could obtain an interactive shell in case the
      script is terminated by an unhandled exception. I would rather
      expect you to get back to the login prompt. I assume you ran the
      program from an interactive shell rather than as a login shell, or
      that you are just concerned about the traceback being displayed on
      the terminal in case of an unhandled exception.

-- 
Florent