Add Constant to _ast_util

Python 3.8 seems to require this be present for expression
generation to succeed.

Fixes: #287
Change-Id: I4a3ac22c74e3c96f5f15d349fc8fe2523d6e7def

3 files changed, 12 insertions, 1 deletions

diff --git a/doc/build/changelog.rst b/doc/build/changelog.rst
index 1e9e698..f330d8f 100644
--- a/doc/build/changelog.rst
+++ b/doc/build/changelog.rst
@@ -9,6 +9,13 @@ Changelog
     :version: 1.0.8
 
     .. change::
+        :tags: bug
+        :tickets: 281
+
+     Fixed an element in the AST Python generator which changed
+     for Python 3.8, causing expression generation to fail.
+
+    .. change::
         :tags: feature
         :tickets: 271
 
diff --git a/mako/_ast_util.py b/mako/_ast_util.py
index c410287..caf157d 100644
--- a/mako/_ast_util.py
+++ b/mako/_ast_util.py
@@ -680,6 +680,10 @@ class SourceGenerator(NodeVisitor):
     def visit_Num(self, node):
         self.write(repr(node.n))
 
+    # newly needed in Python 3.8
+    def visit_Constant(self, node):
+        self.write(repr(node.n))
+
     def visit_Tuple(self, node):
         self.write('(')
         idx = -1
diff --git a/tox.ini b/tox.ini
index 7a89f0a..45d7f00 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,7 +1,7 @@
 # content of: tox.ini , put in same dir as setup.py
 [tox]
 minversion=1.8.dev1
-envlist = py{26,27,34,35,36,37}
+envlist = py{26,27,34,35,36,37,38}
 
 [testenv]
 cov_args=--cov=mako --cov-report term --cov-report xml