- UNDEFINED evaluates to False

CHANGES

diff --git a/CHANGES b/CHANGES
index cead590..ec1e653 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,3 +1,6 @@
+0.1.3
+- UNDEFINED evaluates to False
+
 0.1.2
 - fix to parsing of code/expression blocks to insure that non-ascii
   characters, combined with a template that indicates a non-standard

lib/mako/runtime.py

diff --git a/lib/mako/runtime.py b/lib/mako/runtime.py
index b499249..20748b9 100644
--- a/lib/mako/runtime.py
+++ b/lib/mako/runtime.py
@@ -76,6 +76,9 @@
     """represents an undefined value in a template."""
     def __str__(self):
         raise NameError("Undefined")
+    def __nonzero__(self):
+        return False
+
 UNDEFINED = Undefined()