Support Python object serialization (pickle) of OGRGeometry

[jack.riley@…]

[Originally posted to FWTools list February 2007, and Frank suggested that I submit as an enhancement request against GDAL]

I have a Python (v2.3.5-based) application which stores OGR feature geometry objects (<OGRFeature>.GetGeometryRef().Clone()) in a dict.  To support pickling of these OGRGeometry instances (w/o spatial reference system), I added the following __getstate__ and __setstate__ methods to the Geometry class in (my copy of) ogr.py:

  def __getstate__(self):
      return self.ExportToWkb()
  def __setstate__(self, state):
      result = CreateGeometryFromWkb(state)
      self._o = result._o
      self.thisown = result.thisown
      result.thisown = 0

Note that a similar thing was done in Python Cartographic Library's geometry.py--see trac changeset 411:
http://trac.gispython.org/projects/PCL/changeset/411

Frank's response to my posting of this on the FWTools list included the comment:  "I don't like that the spatial reference would not be captured though I can see that doing so would be quite hard."


Best regards,
Jack