[mousetrap/gnome3-wip: 89/240] Add HaarNameError.

[Heidi Ellis <heidiellis src gnome org>]

commit a251ca4ea7c60ae812ce31262105478f22edadcc
Author: Stoney Jackson <dr stoney gmail com>
Date:   Thu Jun 12 14:17:50 2014 -0400

    Add HaarNameError.

 src/mousetrap/vision.py |   10 ++++++++--
 1 files changed, 8 insertions(+), 2 deletions(-)
---
diff --git a/src/mousetrap/vision.py b/src/mousetrap/vision.py
index 8cb7cae..2a076fd 100644
--- a/src/mousetrap/vision.py
+++ b/src/mousetrap/vision.py
@@ -51,8 +51,7 @@ class HaarLoader(object):
     @staticmethod
     def from_name(name):
         if not name in HaarLoader._haar_files:
-            # TODO: Throw an exception
-            pass
+            raise HaarNameError(name)
 
         haar_file = HaarLoader._haar_files[name]
 
@@ -80,6 +79,13 @@ class HaarLoader(object):
         return haar
 
 
+class HaarNameError(Exception):
+    def __init__(self, message):
+        self.message = message
+    def __str__(self):
+        return repr(self.message)
+
+
 class FeatureDetector(object):
     def __init__(self, name, scale_factor=1.1, min_neighbors=3):
         '''