geopy distance calculation pitfall

Geopy is a great little Python library for working with geocoding and distances using various online services such as Google's geocoder API.

Today I spent nearly half an hour trying to debug what was going on with my web application since I was getting this strange error:

AttributeError: 'VincentyDistance' object has no attribute '_kilometers'

To debug it I wrapped the calls to geopy.distance.distance in various try-and-except statements to see what was going on and run these queries in a separate file. After a while I discovered that was what so special about the coordinates I fed it was that the coordinates where the same. Now my wrapping function looks like this instead:

from geopy import distance as geopy_distance
def geocode_distance((x1, y1), (x2, y2), unit='km'):
   if (x1, y1) == (x2, y2):
       return 0
   d = geopy_distance.distance((x1, y1), (x2, y2))
   if unit == 'miles':
       return d.miles
   else:
       return d.kilometers

Here's the mailing list thread about the very same issue