[GRASS-dev] How to improve flags related error message in pygrass module?

[Nikos Alexandris]

* Markus Neteler <neteler at osgeo.org> [2018-01-15 11:12:46 +0100]:

>Hi devs,
>
>when accidentially using a wrong flag, the resulting error message is
>"unhelpful":
>
>user at fry ~ $ python grass_scripts/grass_dem.py
>GRASSBIN: grass74
>GISBASE: /home/user/source/grass-7.4.svn/dist.x86_64-pc-linux-gnu
>{u'MAPSET': u"'PERMANENT';", u'GISDBASE': u"'/home/user/grassdata';",
>u'LOCATION_NAME': u"'nrw';"}
>Traceback (most recent call last):
>  File "grass_scripts/grass_dem.py", line 17, in <module>
>
>r.in_gdal(input="/home/user/geodaten/ASTGTM2_N50E007_dem.tif",output="dem_nrw",flags="e",overwrite="OVR")
>  File
>"/home/user/source/grass-7.4.svn/dist.x86_64-pc-linux-gnu/etc/python/grass/pygrass/modules/interface/module.py",
>line 647, in __call__
>    self.check()
>  File
>"/home/user/source/grass-7.4.svn/dist.x86_64-pc-linux-gnu/etc/python/grass/pygrass/modules/interface/module.py",
>line 705, in check
>    if flg and flg.suppress_required:
>TypeError: __nonzero__ should return bool or int, returned str
>
>This script was written by a PyGRASS newcomer who reused code from the
>Wiki. The reason for the error is
>overwrite="OVR"
>
>which is incorrect (must be: overwrite=True or =False).

Even like that, the error message is informative.  It expects a boolean
(True or False) or an integer (say: 0 or 1). Instead a string was returned.

Nikos

>The related code is around l705 in
>lib/python/pygrass/modules/interface/module.py
>
>    def check(self):
>        """Check the correctness of the provide parameters"""
>        required = True
>        for flg in self.flags.values():
>            if flg and flg.suppress_required:
>                required = False
>
>Could a python expert here please suggest how to generate a more
>reasonable error message?
>
>thanks
>Markus
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-- 
Nikos Alexandris | Remote Sensing & Geomatics
GPG Key Fingerprint 6F9D4506F3CA28380974D31A9053534B693C4FB3 
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