New --script flag was: Re: [GRASS-dev] how to display a vector map for d.path in gis.m?

[Glynn Clements]

Michael Barton wrote:

> >>> Hmm; it might be useful to have some means of automatically generating
> >>> the corresponding g.parser description for a given command. There are
> >>> probably quite a few scripts whose options are (almost) identical to
> >>> an existing command. I'll look into it.
> >>>     
> >> 
> >> I've extended G_parser() with a --script flag, which writes out a
> >> script with g.parser syntax to mimic the behaviour of the module. This
> >> shoud make it easier to write scripts which mimic an existing command.
> >>   
> > Really cool! Thanks, Glynn.
> 
> Could you explain how this works a bit more? It sounds cool, but I don't
> quite understand how it might be used.

Taking d.path as an example, you would first run e.g.:

	d.path --script > d.path.sh

This will generate a script which contains the g.parser boilerplate
which would be required for a script with the same set of options as
d.path.

To this script, you would append something like the following:

	cmd=d.path
	if [ "$GIS_FLAG_G"	!= 0  ] ; then cmd="$cmd -g"				; fi
	if [ "$GIS_OPT_MAP"	!= "" ] ; then cmd="$cmd map=$GIS_OPT_MAP"		; fi
	if [ "$GIS_OPT_TYPE"	!= "" ] ; then cmd="$cmd type=$GIS_OPT_TYPE"	 	; fi
	if [ "$GIS_OPT_ALAYER"	!= "" ] ; then cmd="$cmd alayer=$GIS_OPT_ALAYER"	; fi
	if [ "$GIS_OPT_NLAYER"	!= "" ] ; then cmd="$cmd nlayer=$GIS_OPT_NLAYER"	; fi
	if [ "$GIS_OPT_AFCOL"	!= "" ] ; then cmd="$cmd afcol=$GIS_OPT_AFCOL"	 	; fi
	if [ "$GIS_OPT_ABCOL"	!= "" ] ; then cmd="$cmd abcol=$GIS_OPT_ABCOL"	 	; fi
	if [ "$GIS_OPT_NCOL"	!= "" ] ; then cmd="$cmd ncol=$GIS_OPT_NCOL"	 	; fi
	if [ "$GIS_OPT_COLOR"	!= "" ] ; then cmd="$cmd color=$GIS_OPT_COLOR"	 	; fi
	if [ "$GIS_OPT_HCOLOR"	!= "" ] ; then cmd="$cmd hcolor=$GIS_OPT_HCOLOR"	; fi
	if [ "$GIS_OPT_BGCOLOR"	!= "" ] ; then cmd="$cmd bgcolor=$GIS_OPT_BGCOLOR"	; fi
	d.vect "$GIS_OPT_MAP"
	exec $cmd

This script should run "d.vect <map>", then run d.path with whatever
options were passed to the d.path.sh script.

Essentially, if you want to write a script which behaves like some
existing command, the --script option can be used to avoid having to
type out the g.parser boilerplate by hand.

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