[GRASSLIST:7690] Re: Interactive GUI input/output

[Paul Kelly]

Glynn Clements wrote:
> Personally, I'd rather modules which are supposed to be
> non-interactive (e.g. r.in.gdal) were fixed so that they really were
> non-interactive. The pervasive assumption that a module can fall back
> to communicating with the user via a terminal is the biggest issue
> standing in the way of a decent GUI for GRASS.

r.in.gdal requires user input if it is creating a new location based on 
the co-ordinate system associated with an external dataset *and* the 
datum specified in that co-ordinate system has more than one possible 
set of transformation parameters. There is no way to automatically 
determine which set is most appropriate; it depends on several factors, 
most notably what part of the country the dataset is situated in.

To make a non-interactive guess or assumption would be lulling the user 
into a false sense of security and might result in loss of accuracy 
later if the most appropriate set of datum parameters had not been 
chosen. IMHO the best way around this is to provide the user with all 
the information available about the various sets of transformation 
parameters and let him or her choose the most appropriate set for the 
area. As there is still no GRASS library for user interaction like this 
the most foolproof way of doing it remains the traditional interactive 
terminal approach.

Hence the problem as outlined previously.

Perhaps the best thing to do for now (although controversial I'm sure) 
might be to remove the capability to automatically create a new location 
from r.in.gdal and v.in.ogr, leaving g.proj as the only module with the 
capability? There could be multiple Tcl/Tk GUI entries for g.proj: one 
of them could be specifically for creating a new location based on the 
co-ordinate system associated with an existing external dataset and this 
could be forced to always spawn a terminal (although it still sometimes 
wouldn't be needed, e.g. when creating a WGS84 location where there is 
only one possible set of datum transformation parameters). This 
functionality should probably also be added to the start-up screen. But 
I know virtually nothing of the GRASS GUI especially the recent 
improvements.

Paul