[GRASS-dev] libgis: G_FATAL_EXIT|PRINT|RETURN

[Markus Metz]

On Sun, Apr 7, 2013 at 11:21 AM, Martin Landa <landa.martin at gmail.com> wrote:
> Hi,
>
> 2013/4/6 Markus Metz <markus.metz.giswork at gmail.com>:
>>> These defines are used by a few functions, eg.
>>> G_check_input_output_name(). Other candidates could eg.
>>> Vect_open_old() and similar functions (eg. call G__error() when vector
>>> map is not found). I would suggest to add G__error() and
>>> G__set_error_code() just for internal use (see the attached path).
>>
>> What's your motivation for adding G__error() and G__set_error_code()?
>> Are there problems with e.g. Vect_open_old()?
>
> first of all, G_FATAL_EXIT|PRINT|RETURN codes exist in libgis for a
> long time. Some functions use them as an argument. In raster library
> Rast_open_old() calls G_fatal_error() when raster map is not found.
> Currently Vect_open_old() calls G_warning() and return -1. Some vector
> modules do not check return code of Vect_open_old().

Previous to r49405, Vect_open_old() called G_fatal_error() by default,
therefore there was no need to check if Vect_open_old() failed. Vector
modules were not updated for the changes introduced with r49405.

> My idea was to
> call G__error() when vector map is not found. Then the program would
> terminate if `err_code` in `error.c` is G_FATAL_EXIT. Otherwise
> message would be printed out (G_FATAL_PRINT) or the function would
> finish just with return code without printing any message
> (G_FATAL_RETURN). Similarly to G_check_input_output(), adding
> G__error() and G__set_error_code() would also avoid adding extra
> arguments to these functions.

Why not just use G_fatal_error() like Rast_open_old()? Why this more
complicated G_FATAL_EXIT|PRINT|RETURN?

BTW, you changed some G_fatal_error() to G_warning(), particularly for
Vect_write_line() and Vect_delete_line(). Consequently, the return
values need now be checked whenever these functions are called (very
often). IMHO, it is worth a fatal error if Vect_write_line() or
Vect_delete_line() fail.

Markus M