Re: [gdal-dev] Towards more user-friendly error messages
Even Rouault wrote: Ari, It's funny because I myself got caught by the same issue a few days ago. So I've just improved error reporting on shapefile layer for SetFeature(), CreateFeature() and DeleteFeature() operations in trunk (r17255). It was trivial in that case as the OGRShapeLayer object has a flag to indicate if it is opened in read-only or update mode. I'm not sure there is a policy for error reporting and how it could be formulated if there was one ! If we can make it clearer in situations where it is not currently, just report it as you did. Ari / Even, My position is that the higher level methods like SetFeature(), CreateFeature() etc ought to be checking read-only status and providing informative errors. In general we need to try and issue informative errors at the highest level we can for the sake of users and developers. Best regards, -- ---+-- I set the clouds in motion - turn up | Frank Warmerdam, warmer...@pobox.com light and sound - activate the windows | http://pobox.com/~warmerdam and watch the world go round - Rush| Geospatial Programmer for Rent ___ gdal-dev mailing list gdal-dev@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/gdal-dev
Re: [gdal-dev] Towards more user-friendly error messages
Ari, It's funny because I myself got caught by the same issue a few days ago. So I've just improved error reporting on shapefile layer for SetFeature(), CreateFeature() and DeleteFeature() operations in trunk (r17255). It was trivial in that case as the OGRShapeLayer object has a flag to indicate if it is opened in read-only or update mode. I'm not sure there is a policy for error reporting and how it could be formulated if there was one ! If we can make it clearer in situations where it is not currently, just report it as you did. I'd note that you can check for most operations on OGR Layers if they are possible by using the TestCapability() method, which is mapped to swig. For example, for SetFeature() with the OLCRandomWrite flag. (By the way, in that commit I've also fixed a few cases where the answer was not correct for other flags) Best regards, Even Le Wednesday 17 June 2009 16:25:04 Ari Jolma, vous avez écrit : > A colleague of mine is beginning to use GDAL via the Perl bindings (the > bindings are not the main issue however). He makes quite simple errors, > but is perplexed when he gets rather scary looking / uninformative error > messages. For example he forgot to open Shapefile with update turned on > (it is by default off at least in Perl bindings) and when he then calls > SetFeature the error is: > > RuntimeError Error in psSHP->sHooks.FSeek() or fwrite() writing object > to .shp file. > > Which for the initiated hints that maybe the file was opened read-only, > but for a newbie is just scary. > > In this case there are two issues: > > - the error is at layer method, although the data source was opened > read-only (does the layer know its data source and is it easy to query > from the data source, how it was opened - at least in the bindings > there's no method for that?) > > - where to report the error nicely, for example "Can't call SetFeature > with a read-only layer, you moron." > > Is this a policy issue, or is this a case-by-case issue? How could we > find and list the frequently made mistakes? > > Regards, > > Ari ___ gdal-dev mailing list gdal-dev@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/gdal-dev
[gdal-dev] Towards more user-friendly error messages
A colleague of mine is beginning to use GDAL via the Perl bindings (the bindings are not the main issue however). He makes quite simple errors, but is perplexed when he gets rather scary looking / uninformative error messages. For example he forgot to open Shapefile with update turned on (it is by default off at least in Perl bindings) and when he then calls SetFeature the error is: RuntimeError Error in psSHP->sHooks.FSeek() or fwrite() writing object to .shp file. Which for the initiated hints that maybe the file was opened read-only, but for a newbie is just scary. In this case there are two issues: - the error is at layer method, although the data source was opened read-only (does the layer know its data source and is it easy to query from the data source, how it was opened - at least in the bindings there's no method for that?) - where to report the error nicely, for example "Can't call SetFeature with a read-only layer, you moron." Is this a policy issue, or is this a case-by-case issue? How could we find and list the frequently made mistakes? Regards, Ari -- Prof. Ari Jolma Environmental Management Information Technology Teknillinen Korkeakoulu / Helsinki University of Technology tel: +358 9 4511 address: POBox 5300, 02015 TKK, Finland Email: ari.jolma at tkk.fi URL: http://geoinformatics.tkk.fi ___ gdal-dev mailing list gdal-dev@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/gdal-dev
