Implement importutils.try_import.

Adds a new (simple) importutils.try_import function which
can return a module name or a default (by default this is None).

This should help clean up some of our

try:
    import foo
except...

blocks in modules.

This commit also drops the dependency on python-extras which is
no longer needed.

Fixes LP Bug #1099501.

Change-Id: I8591f79983bdad67a50d1aaae6dce8428dfce084

1 files changed, 8 insertions, 0 deletions

diff --git a/tests/unit/test_importutils.py b/tests/unit/test_importutils.py
index 4c9ff73..3544fe4 100644
--- a/tests/unit/test_importutils.py
+++ b/tests/unit/test_importutils.py
@@ -109,3 +109,11 @@ class ImportUtilsTest(unittest.TestCase):
         dt = importutils.import_object('datetime.datetime', 2012, 4, 5)
         self.assertTrue(isinstance(dt, sys.modules['datetime'].datetime))
         self.assertEqual(dt, datetime.datetime(2012, 4, 5))
+
+    def test_try_import(self):
+        dt = importutils.try_import('datetime')
+        self.assertEqual(sys.modules['datetime'], dt)
+
+    def test_try_import_returns_default(self):
+        foo = importutils.try_import('foo.bar')
+        self.assertEqual(None, foo)