[GRASS-user] r.fillnulls in the latest cvs version doesn't work appropriately

[Glynn Clements]

Martin Landa wrote:

> > > -g implies that you want output. You shouldn't have to add -p as well.
> > > I still don't fully understand the logic of why it was changed.
> 
> my idea was to make the -g flag more general (i.e. *"how"* to print
> not "what" to print).
> 
> >
> > The idea was that the choices of what to print and how to print it are
> > orthogonal.
> >
> > There should be a fallback so that if you don't specify *what* to
> > print, -p should be assumed. However, the code which is meant to do
> > this isn't sufficiently general; it treats -g as -gp and -gz as -gzp,
> > but doesn't add -p in other cases which might need it.
> >
> > Rather than having one variable (print_flag), there should be two: one
> > for the "what" and another for the "how". If the "what" is empty, it
> > should add -p.
> 
> I agree,
> 
> *what* to print
> #define PRINT_REG    0x01
> #define PRINT_LL     0x04
> #define PRINT_EXTENT 0x08
> #define PRINT_CENTER 0x10
> #define PRINT_METERS 0x20
> #define PRINT_3D     0x40
> #define PRINT_MBBOX  0x80
> 
> *how* to print:
> #define PRINT_SH     0x02
> 
> should be OK?

I would have thought that PRINT_LL and PRINT_METERS should be in the
"how" category. I'm aware that the issue is complicated by the fact
that the existing flags combine "what" and "how":

       -p  Print the current region
       -l  Print the current region in lat/long on current ellipsoid/datum
       -e  Print the current region extent
       -c  Print the current region map center coordinates
       -m  Print region resolution in meters (geodesic)
       -3  Print also 3D settings
       -b  Print the maximum bounding box in lat/long on WGS84
       -g  Print in shell script style

E.g. -m combines a what (resolution) with a how (metres).

AFAICT, the "what" category consists of:

	region (bounds, resolution, rows/cols)
	extent
	centre
	resolution only
	also 3D (Z) values

while the "how" category consists of:

	shell-script style ("key=value" rather than "key: value")
	metres (for lat/lon locations)
	degrees (for projected locations)

Any position or dimension should be able to be output in metres,
degrees, or the location's units (in case it uses neither metres nor
degrees, but e.g. feet).

The output should be available in either "key: value" style (with
padding to align the "value" column) or "key=value" style.

The bounds, resolution, extent, and centre can be either 2D or 3D.

Thinking about it, the existing mess of printing flags is probably too
far gone to be put into any sane framework without creating major
compatibility problems.

It may be better to simply add a print= option which takes a list of
keywords, each of which controls a single "what" or "how" choice,
e.g.:

	g.region print=bounds,resolution,center,meters,shell

would output:

	n=4928010
	s=4913700
	w=589980
	e=609000
	nsres=30
	ewres=30
	center_northing=4920855
	center_easting=599490

-- 
Glynn Clements <glynn at gclements.plus.com>