[GRASS-dev] [grass-code I][478] tcl/tk gui startup screen launches grass even when 'Exit' is pushed

[Maris Nartiss]

Hi, some comments inline.
2007/9/24, Paul Kelly <paul-grass at stjohnspoint.co.uk>:
> Hello all
> (sorry for delayed response on this; been travelling a lot and only have
> time to "dip in" to mailing list discussions at the minute...)
>

> I think it's a good idea to change the behaviour here, but I feel the
> patch doesn't really address the problem: rather it adds more code to work
> around it.
Hm. 6 lines isn't a lot and those lines fix probelm instead of
working-a-round it.

>In particular, clicking exit in the gis_set.tcl Window won't
> work with init.bat (Windows) now, as it used the exit code of 1 to
> indicate exit (whereas the patch makes an exit code of 2 now indicate
> exit). I notice also the patch makes the exit code of the Python version
> of gis_set.tcl be interpreted differently - has anybody checked what
> effect this will have?
Before this patch GUI exit code was not used at all due wrong use of
eval. It should not affect Python version at all, but I can not test
it as still there is no Gentoo ebuild for recent wx* stuff.
About init.bat You are right - it needs to be fixed. Please, fix this in CVS.
Exit code "2" isn't mandatory, it just can NOT be 0 (success - launch
GRASS) or 1 (error - use some failback or other things for error
handling).

>
> The problem is the historical behaviour that an error in gis_set.tcl (e.g.
> the wrong version of Tcl/Tk) caused it to drop out from attempting the GUI
> startup but go ahead and start an interactive GRASS shell. When I made
> a few changes to the return codes from gis_set.tcl I deliberately avoided
> tackling this because I wasn't sure what was the best solution. But on
> thinking about it more, I think dropping to an interactive shell is the
> wrong approach. It should print a warning/error message and then exit, and
> if the user wants to start in text-based mode instead they can use the
> -text switch next time round.
This is debatable question - what's better - provide failback
mechanism or just give error message. IMHO better is to use some
failback, as most errors are trapped within gis_set and exit code 1
should mean some serious error.

>
> init.bat assumes a return code of 1 means exit. I vaguely intended the
> same interpretation for Init.sh, and to remove the facility to drop to an
> interactive shell when there was an error in gis_set.tcl, but I didn't
> implement this nor tell anybody about my plans: my fault ;)
User exit is not an error. As GRASS is hybrid GUI/CLI system, there
should be some clear exit code for user's canceled action instead of
error.

>
> I think it would simplify things if we made Init.sh always exit when a
> non-zero exit code is returned from gis_set.tcl- any other thoughts? (I
> should probably update init.bat too so it goes ahead when 0 is returned,
> rather than exiting when 1 is returned).
As I wrote - user exit is not an error. If You think, that GRASS
should not use text mode as failback - that's OK, but still there
should be as minimum 3 cases - no error (start GRASS); error (print
error and exit or use text mode) and user exit (just exit GRASS).

>
> Paul
>

Thanks for Your input,
Maris.