Introduce dynamic scope_path regexps Instead of relying on scope_path's being "one slash deep", we should instead allow for either: 1. scope_paths that have a pre-defined depth 2. scope_paths that can be arbitrarily deep We achieve 1 by setting an entities scope_logic to another logic module. We then recursively call getScopeDepth until we get to the topmost entity (that is, an unscoped entity). A little different is the solution to 2, since some entities can have an arbitrarily deep scope (such as Documents), we need to have some way of signaling this to getScopePattern. A clean solution is to return None, rather than a number. If None is returned, the SCOPE_PATH_ARG_PATTERN is returned as regexp instead, which will match an arbitrarily deeply nested scope. The solution for 2 requires that we return None somewhere in the scope_logic chain, the most straight forward method to do so is to override getScopeDepth anywhere such a scope is needed and make it return None. A more elegant solution however, is to set the scope_logic to that module in all entities that require it. Patch by: Sverre Rabbelier

"""
 This module holds the base `SpatialBackend` object, which is
 instantiated by each spatial backend with the features it has.
"""
# TODO: Create a `Geometry` protocol and allow user to use
# different Geometry objects -- for now we just use GEOSGeometry.
from django.contrib.gis.geos import GEOSGeometry, GEOSException

class BaseSpatialBackend(object):
    Geometry = GEOSGeometry
    GeometryException = GEOSException

    def __init__(self, **kwargs):
        kwargs.setdefault('distance_functions', {})
        kwargs.setdefault('limited_where', {})
        for k, v in kwargs.iteritems(): setattr(self, k, v)
 
    def __getattr__(self, name):
        """
        All attributes of the spatial backend return False by default.
        """
        try:
            return self.__dict__[name]
        except KeyError:
            return False