I have changed r.mapcalc in 7.x to use G_parser():
$ r.mapcalc --help
Description:
Raster map calculator.
Keywords:
raster
Usage:
r.mapcalc [expression=string] [input=name] [--overwrite] [--verbose]
[--quiet]
Flags:
--o Allow output files to overwrite existing files
--v Verbose module output
--q Quiet module output
Parameters:
expression Expression to evaluate
input File containing expression to evaluate
Note that, as expression= is the first option, it is the default. This
means that passing an expression on the command line is compatible
with both the old and new interfaces, so long as you:
a) quote the expression, and
b) include a space before the first = sign.
E.g.:
r.mapcalc "foo = 1"
or:
r.mapcalc 'foo = 1'
An unquoted expression (i.e. split over multiple arguments) won't
work, nor will omitting the space before the = sign:
$ r.mapcalc 'foo=1'
Sorry, <foo> is not a valid parameter
If no options are given, it manufactures "input=-" (which reads from
stdin), so you can continue to use e.g.:
r.mapcalc < file
or:
r.mapcalc <<EOF
foo = 1
EOF
But unless you need compatibility with previous versions, use input=
explicitly, e.g.:
r.mapcalc input=file
or:
r.mapcalc input=- <<EOF
foo = 1
EOF
Also, it now recognises --o[verwrite] and $GRASS_OVERWRITE, so you
will get an error if you try to overwrite an existing map without one
of those.
Note that older versions don't understand --o, so if you want to write
a shell script which is compatible with both versions, and which will
overwrite existing maps, use e.g.:
GRASS_OVERWRITE=1 r.mapcalc 'foo = 1'
Python scripts only need to work with 7.x, so you can just use --o (or
overwrite=True with grass.run_command etc).
--
Glynn Clements <glynn@gclements.plus.com>