[Qgis-developer] QgsField::length semantic

[Even Rouault]

> According to this:
> http://devzone.advantagedatabase.com/dz/webhelp/advantage9.0/server1/dbf_fi
> eld_types_and_specifications.htm
> 
> A DBF field with extended data type "double" does not affect the
> precision of the stored data, and the length information is simply
> ignored.

I had never seen such "double" type in use in .dbf, and it is certainly not 
handled by shapelib/OGR, and I have never seen reports that other shapefile 
producing software generate such field types. Might be a "Visual FoxPro" 
specific thing.

> 
> After all, a "Double" in a DBF is just 8 bytes anyway, so why bother
> attempting to go beyond that ? Qgis is storing values in a Double too,
> and the only reason I see to support "numeric" is storing arbitrary
> precision values, which don't seem to be supported by OGR:
> http://www.gdal.org/ogr__core_8h.html#a787194bea637faf12d61643124a7c9fc

True, OGR ends up storing numeric fields as C double. The width/precision is 
mostly informative (and occasionnaly indeed an annoyance when backends start 
using it...)

> 
> --strk;
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