Merge 845fbe7 into 1808232

zopefoundation · Jun 17, 2020 · aafe767 · aafe767
2 parents 1808232 + 845fbe7
commit aafe767
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Showing 5 changed files with 33 additions and 1 deletion.
diff --git a/CHANGES.rst b/CHANGES.rst
@@ -10,6 +10,9 @@ https://zope.readthedocs.io/en/2.13/CHANGES.html
 4.4.4 (unreleased)
 ------------------
 
+- Fix ``default`` keyword handling in page templates
+  (`#846 <https://github.com/zopefoundation/Zope/issues/846>`_)
+
 - Update dependencies to newest bugfix releases.
 
 

diff --git a/src/Products/PageTemplates/engine.py b/src/Products/PageTemplates/engine.py
@@ -328,7 +328,18 @@ def __call__(self, context, macros, tal=True, **options):
         kwargs["__zt_engine__"] = self.engine
         kwargs["__zt_context__"] = context
 
-        return self.template.render(**kwargs)
+        template = self.template
+        # work around ``https://github.com/zopefoundation/Zope/issues/846``
+        template.cook_check()  # ensure `_render` is computed
+        rf = getattr(template, "_render", None)
+        if rf is not None:
+            defs = [c for c in rf.__code__.co_consts if c == '__default']
+            if len(defs) == 1:
+                # use the template's private ``default`` representation
+                # as our TALES ``default`` value
+                kwargs["default"] = defs[0]
+
+        return template.render(**kwargs)
 
     @classmethod
     def cook(cls, source_file, text, engine, content_type):

diff --git a/src/Products/PageTemplates/tests/input/Default.html b/src/Products/PageTemplates/tests/input/Default.html
@@ -0,0 +1,8 @@
+<html>
+<head></head>
+<body>
+<p tal:define="foo string:"
+   tal:content="python: foo or default">Default in Python expression</p>
+<p tal:content="context/I_Fail|default">Default in Path expression</p>
+</body>
+</html>
diff --git a/src/Products/PageTemplates/tests/output/Default.html b/src/Products/PageTemplates/tests/output/Default.html
@@ -0,0 +1,7 @@
+<html>
+<head></head>
+<body>
+<p>Default in Python expression</p>
+<p>Default in Path expression</p>
+</body>
+</html>
diff --git a/src/Products/PageTemplates/tests/testHTMLTests.py b/src/Products/PageTemplates/tests/testHTMLTests.py
@@ -189,3 +189,6 @@ def testBadExpression(self):
 
     def testPathAlternativesWithSpaces(self):
         self.assert_expected(self.folder.t, 'PathAlternativesWithSpaces.html')
+
+    def testDefaultKeywordHandling(self):
+        self.assert_expected(self.folder.t, 'Default.html')