--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/app/django/contrib/gis/db/models/proxy.py	Tue Oct 14 16:00:59 2008 +0000
@@ -0,0 +1,62 @@
+"""
+ The GeometryProxy object, allows for lazy-geometries.  The proxy uses
+ Python descriptors for instantiating and setting Geometry objects
+ corresponding to geographic model fields.
+
+ Thanks to Robert Coup for providing this functionality (see #4322).
+"""
+
+from types import NoneType, StringType, UnicodeType
+
+class GeometryProxy(object): 
+    def __init__(self, klass, field): 
+        """
+        Proxy initializes on the given Geometry class (not an instance) and 
+        the GeometryField.
+        """
+        self._field = field 
+        self._klass = klass
+     
+    def __get__(self, obj, type=None): 
+        """
+        This accessor retrieves the geometry, initializing it using the geometry
+        class specified during initialization and the HEXEWKB value of the field.  
+        Currently, only GEOS or OGR geometries are supported.
+        """
+        # Getting the value of the field.
+        geom_value = obj.__dict__[self._field.attname] 
+        
+        if isinstance(geom_value, self._klass): 
+            geom = geom_value
+        elif (geom_value is None) or (geom_value==''):
+            geom = None
+        else: 
+            # Otherwise, a Geometry object is built using the field's contents,
+            # and the model's corresponding attribute is set.
+            geom = self._klass(geom_value)
+            setattr(obj, self._field.attname, geom) 
+        return geom 
+     
+    def __set__(self, obj, value):
+        """
+        This accessor sets the proxied geometry with the geometry class
+        specified during initialization.  Values of None, HEXEWKB, or WKT may
+        be used to set the geometry as well.
+        """
+        # The OGC Geometry type of the field.
+        gtype = self._field._geom
+        
+        # The geometry type must match that of the field -- unless the
+        # general GeometryField is used.
+        if isinstance(value, self._klass) and (str(value.geom_type).upper() == gtype or gtype == 'GEOMETRY'):
+            # Assigning the SRID to the geometry.
+            if value.srid is None: value.srid = self._field._srid
+        elif isinstance(value, (NoneType, StringType, UnicodeType)):
+            # Set with None, WKT, or HEX
+            pass
+        else:
+            raise TypeError('cannot set %s GeometryProxy with value of type: %s' % (obj.__class__.__name__, type(value)))
+
+        # Setting the objects dictionary with the value, and returning.
+        obj.__dict__[self._field.attname] = value 
+        return value