Make sure ZopePythonExpr and PythonExpr are separate classes

There are ZCML files out there (zope.app.pagetemplate) that want to
define permissions for ZopePythonExpr and PythonExpr, and get conflicts
if these are two names referring to the same class.

2 files changed, 11 insertions, 10 deletions

diff --git a/CHANGES.txt b/CHANGES.txt
index c76212f..cdc1d94 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -5,8 +5,9 @@ CHANGES
 4.0.4 (unreleased)
 ------------------
 
-- Nothing changed yet.
-
+- Make sure ``ZopePythonExpr`` and ``PythonExpr`` are separate classes even
+  when ``zope.untrustedpython`` is not available.  Fixes a ZCML conflict error
+  in ``zope.app.pagetemplate``.
 
 4.0.3 (2013-02-28)
 ------------------
diff --git a/src/zope/pagetemplate/engine.py b/src/zope/pagetemplate/engine.py
index d74e137..99634fa 100644
--- a/src/zope/pagetemplate/engine.py
+++ b/src/zope/pagetemplate/engine.py
@@ -95,16 +95,16 @@ class TrustedZopePathExpr(PathExpr):
 
 class ZopePythonExpr(PythonExpr):
 
-    def __call__(self, econtext):
-        __traceback_info__ = self.text
-        vars = self._bind_used_names(econtext, SafeBuiltins)
-        return eval(self._code, vars)
+    if HAVE_UNTRUSTED:
 
-    def _compile(self, text, filename):
-        return rcompile.compile(text, filename, 'eval')
+        def __call__(self, econtext):
+            __traceback_info__ = self.text
+            vars = self._bind_used_names(econtext, SafeBuiltins)
+            return eval(self._code, vars)
+
+        def _compile(self, text, filename):
+            return rcompile.compile(text, filename, 'eval')
 
-if not HAVE_UNTRUSTED:
-    ZopePythonExpr = PythonExpr
 
 class ZopeContextBase(Context):
     """Base class for both trusted and untrusted evaluation contexts."""