empty object managers were evaluating to boolean false since Hanno fully...

empty object managers were evaluating to boolean false since Hanno fully implemented IContainer, because boolean checks fall through to __len__ if __nonzero__ is not implemented.  always evaluating to true is the backwards-compatible approach

doc/CHANGES.rst

@@ -32,6 +32,10 @@ Restructuring
   newer versions of the dependencies. This kind of KGS information needs
   to be expressed in a different way.
 
+Bugs Fixed
+++++++++++
+
+- Object managers should evaluate to True in a boolean test.
 
 2.12.0a1 (2009-02-26)
 ---------------------

src/OFS/ObjectManager.py

@@ -789,6 +789,9 @@ class ObjectManager(CopyContainer,
     def __len__(self):
         return len(self.objectIds())
 
+    def __nonzero__(self):
+        return True
+
     security.declareProtected(access_contents_information, 'get')
     def get(self, key, default=None):
         return self._getOb(key, default)

src/OFS/tests/testObjectManager.py

@@ -379,6 +379,10 @@ class ObjectManagerTests(PlacelessSetup, unittest.TestCase):
         om['2'] = si2
         self.failUnless(len(om) == 2)
 
+    def test_nonzero(self):
+        om = self._makeOne()
+        self.failUnless(om)
+
     def test_get(self):
         om = self._makeOne()
         si1 = SimpleItem('1')