[GRASS5] Need help debugging problem with thematic mapping script

[Michael Barton]

Thanks much Glynn.

If I add >/dev/null or >@stdout to the grass commands (d.mon only?) inside
d.vect.thematic will this do the trick? Any reason to choose one over the
other? 

The run_panel procedure in d.m.tcl traps stdout at the level of the tcl open
command, at least. Will this carry through to the output from commands
inside the script if I use >@stdout?

Michael
______________________________
Michael Barton, Professor of Anthropology
School of Human Evolution and Social Change
Arizona State University
Tempe, AZ  85287-2402
USA

voice: 480-965-6262; fax: 480-965-7671
www: http://www.public.asu.edu/~cmbarton


> From: Glynn Clements <glynn at gclements.plus.com>
> Date: Mon, 14 Nov 2005 09:58:02 +0000
> To: Michael Barton <michael.barton at asu.edu>
> Cc: Grass Developers List <grass5 at grass.itc.it>
> Subject: Re: [GRASS5] Need help debugging problem with thematic mapping script
> 
> 
> Michael Barton wrote:
> 
>> I¹ve run into a small but annoying bug that shows up when implementing the
>> thematic mapping script in the GIS Manager.  I¹ve tried innumerable ways to
>> fix this...trying tweaks in d.m.tcl, d.vect.thematic, and thematic.tcl--but
>> it
>> still occurs. Here is the strange behavior.
>> 
>> If you create a thematic map layer in the GIS Manager, and select the option
>> to create a graphic legend, the GIS Manager will hang unless the monitor for
>> the legend display is already running. If the monitor for the legend is NOT
>> running, d.vect.thematic will start the monitor and draw the legend.
>> However, all processing will then stop and the GIS Manager will hang. If you
>> close this monitor, processing will continue and the GIS Manager will
>> respond. If the monitor chosen for the legend IS running, processing will
>> proceed normally.
>> 
>> As far as I can tell, this behavior is the same regardless of how the script
>> is actually run in the GIS Manger (i.e., run using the TclTk open command,
>> run in a terminal, run using exec, etc.).
>> 
>> Here is what is actually happening in the script. If you create a thematic
>> map layer in the GIS Manager, and select the option to create a graphic
>> legend, the d.vect.thematic script will use an if clause to check to see if
>> the monitor selected for the legend is running. If the monitor chosen for
>> the legend is NOT running, the script will start the monitor (d.mon start=).
>> If it IS running, the script will select that monitor (d.mon select=). Then
>> the script will continue to erase the monitor (d.erase), draw the legend
>> using d.graph (d.graph input=), and reselect the original display monitor
>> used for thematic map display (d.mon select=).
> 
> Tcl's exec command (which is being called by the default undefined
> command handler; you're trying to run d.mon as a Tcl command, where it
> should really be "exec d.mon ...") sets the process' stdout to a pipe.
> 
> The result of the exec command is the data which the process writes to
> its stdout (the pipe), so exec can't return until it receives EOF,
> i.e. when the write end of the pipe has been closed.
> 
> The driver is a child of d.mon, and so inherits the pipe as its
> stdout. It never closes it, so the exec command won't get EOF and
> won't terminate.
> 
> The easiest solution is to add >/dev/null or >@stdout to the exec
> command.
> 
> -- 
> Glynn Clements <glynn at gclements.plus.com>