Merge pull request #695 from QuLogic/optional-pillow

Make cartopy.feature.WFSFeature imports lazier.

lib/cartopy/feature.py

@@ -29,7 +29,6 @@
 import shapely.geometry
 import six
 
-from cartopy.io.ogc_clients import WFSGeometrySource
 import cartopy.io.shapereader as shapereader
 import cartopy.crs
 
@@ -298,6 +297,8 @@ class WFSFeature(Feature):
     A class capable of drawing a collection of geometries
     obtained from an OGC Web Feature Service (WFS).
 
+    This feature requires additional dependencies. If installed via pip,
+    try ``pip install cartopy[ows]``.
     """
     def __init__(self, wfs, features, **kwargs):
         """
@@ -315,6 +316,12 @@ def __init__(self, wfs, features, **kwargs):
             Keyword arguments to be used when drawing this feature.
 
         """
+        try:
+            from cartopy.io.ogc_clients import WFSGeometrySource
+        except ImportError as e:
+            six.raise_from(ImportError(
+                'WFSFeature requires additional dependencies. If installed '
+                'via pip, try `pip install cartopy[ows]`.\n'), e)
 
         self.source = WFSGeometrySource(wfs, features)
         crs = self.source.default_projection()

requirements/ows.txt

@@ -1 +1,2 @@
 OWSLib>=0.8.7
+pillow>=1.7.8