Use Python expression from z3c.pt (which is compatible with Zope)…

…. This was already the case for the untrusted Zope 2 expression, but not for the trusted Zope 3 expression.

CHANGES.txt

@@ -1,6 +1,16 @@
 Changelog
 =========
 
+In next release ...
+
+- Use the Python expression from the ``z3c.pt`` package for the
+  trusted page template engine. This difference between this and the
+  standard Python expression from Chameleon is that the pipe character
+  (``"|"``) has the meaning of fallback in Chameleon, but not in the
+  reference ZPT implementation (where it's only available for path
+  expressions).
+  [malthe]
+
 2.1.1 (2011-07-15)
 ~~~~~~~~~~~~~~~~~~
 

src/five/pt/patches.py

@@ -19,9 +19,10 @@
 
 from chameleon.tales import StringExpr
 from chameleon.tales import NotExpr
-from chameleon.tales import PythonExpr
 from chameleon.tal import RepeatDict
 
+from z3c.pt.expressions import PythonExpr
+
 from .expressions import PathExpr
 from .expressions import TrustedPathExpr
 from .expressions import ProviderExpr
@@ -30,6 +31,7 @@
 from .expressions import UntrustedPythonExpr
 
 
+
 # Declare Chameleon's repeat dictionary public
 RepeatDict.security = ClassSecurityInfo()
 RepeatDict.security.declareObjectPublic()