make Extension responsible for formatting its target name

2 files changed, 15 insertions, 5 deletions

diff --git a/stevedore/driver.py b/stevedore/driver.py
index ea2e122..54cdcae 100644
--- a/stevedore/driver.py
+++ b/stevedore/driver.py
@@ -34,12 +34,12 @@ class DriverManager(NamedExtensionManager):
             raise RuntimeError('No %r driver found, looking for %r' %
                                (namespace, name))
         if len(self.extensions) > 1:
+            discovered_drivers = ','.join(e.entry_point_target
+                                          for e in self.extensions)
+
             raise RuntimeError('Multiple %r drivers found: %s' %
-                               (namespace,
-                                ','.join('%s:%s' % (e.entry_point.module_name,
-                                                    e.entry_point.attrs[0])
-                                         for e in self.extensions))
-                               )
+                               (namespace, discovered_drivers))
+
 
     def __call__(self, func, *args, **kwds):
         """Invokes func() for the single loaded extension.
diff --git a/stevedore/extension.py b/stevedore/extension.py
index a29af8e..ec71279 100644
--- a/stevedore/extension.py
+++ b/stevedore/extension.py
@@ -34,6 +34,16 @@ class Extension(object):
         self.plugin = plugin
         self.obj = obj
 
+    @property
+    def entry_point_target(self):
+        """The module and attribute referenced by this extension's entry_point.
+
+        :return: A string representation of the target of the entry point in
+            'dotted.module:object' format.
+        """
+        return '%s:%s' % (self.entry_point.module_name,
+                          self.entry_point.attrs[0])
+
 
 class ExtensionManager(object):
     """Base class for all of the other managers.