[GRASS-dev] r.external no cats file?

Glynn Clements glynn at gclements.plus.com
Tue Jun 28 18:23:53 EDT 2011

Markus Metz wrote:

> When linking external raster maps with r.external, I have to manually
> create a corresponding cats file, otherwise a number of modules, e.g.
> d.rast do not work properly. Is there any reason why no corresponding
> cats file is produced?

IMHO, modules should not be required to explicitly write a cats file. 
GRASS 4.x is ancient history, and raster maps are no longer inherently

Raster modules should only write a cats file if they actually have
something meaningful to put in it.

Either Rast_read_cats() should silently return an empty category
structure if no cats file is present, or Rast_close() should
automatically generate an empty cats file if no cats file was
explicitly written.

I'm inclined towards the former, unless there might be cases where the
distinction between "no category list" and "empty category list" would

Glynn Clements <glynn at gclements.plus.com>

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