Avoid deprecation warnings when using Python 3.8+. (#218)

.meta.toml

@@ -2,7 +2,7 @@
 # https://github.com/zopefoundation/meta/tree/master/config/pure-python
 [meta]
 template = "pure-python"
-commit-id = "3ffdf08eda5163647c93d7e25faca354d176ae77"
+commit-id = "886173bf647a6e80a985544c32053c932b1949e2"
 
 [python]
 with-pypy = false
@@ -51,7 +51,7 @@ testenv-additional = [
     "    coverage combine",
     "    coverage html",
     "    coverage report -m --fail-under=100",
-    "depends = py27,py35,py36,py39-datetime,py37,py38,py39,coverage",
+    "depends = py27,py35,py36,py37,py38,py39,py39-datetime,py310,coverage",
     ]
 coverage-basepython = "python3.8"
 coverage-command = "pytest --cov=src --cov=tests --cov-report= {posargs}"
@@ -60,7 +60,7 @@ coverage-setenv = [
     ]
 
 [coverage]
-fail-under = 98.9
+fail-under = 98.7
 
 [manifest]
 additional-rules = [

CHANGES.rst

@@ -6,6 +6,9 @@ Changes
 
 - Document that ``__name__`` is needed to define classes.
 
+- Avoid deprecation warnings when using Python 3.8+.
+  (`#192 <https://github.com/zopefoundation/RestrictedPython/issues/192>`_)
+
 - Allow to use the package with Python 3.10 -- Caution: No security audit has
   been done so far.
 

constraints.txt

@@ -5,3 +5,6 @@ isort >= 4.3.2
 # Needed for Appveyor as long as PY2 is supported:
 pytest < 5
 pytest-html < 2
+# coverage 6+ no longer supports Python 2 and coverage results of older
+# versions cannot not combined with newer ones:
+coverage < 6

src/RestrictedPython/transformer.py

@@ -26,6 +26,7 @@
 from ._compat import IS_PY3
 from ._compat import IS_PY34_OR_GREATER
 from ._compat import IS_PY35_OR_GREATER
+from ._compat import IS_PY38_OR_GREATER
 
 import ast
 import contextlib
@@ -541,27 +542,65 @@ def node_contents_visit(self, node):
 
     # ast for Literals
 
-    def visit_Num(self, node):
-        """Allow integer numbers without restrictions.
+    if IS_PY38_OR_GREATER:
 
-        Replaced by Constant in Python 3.8.
-        """
-        return self.node_contents_visit(node)
+        def visit_Constant(self, node):
+            """Allow constant literals with restriction for Ellipsis.
 
-    def visit_Str(self, node):
-        """Allow string literals without restrictions.
+            Constant replaces Num, Str, Bytes, NameConstant and Ellipsis in
+            Python 3.8+.
+            :see: https://docs.python.org/dev/whatsnew/3.8.html#deprecated
+            """
+            if node.value is Ellipsis:
+                # Deny using `...`.
+                # Special handling necessary as ``self.not_allowed(node)``
+                # would return the Error Message:
+                # 'Constant statements are not allowed.'
+                # which is only partial true.
+                self.error(node, 'Ellipsis statements are not allowed.')
+                return
+            return self.node_contents_visit(node)
 
-        Replaced by Constant in Python 3.8.
-        """
-        return self.node_contents_visit(node)
+    else:
 
-    def visit_Bytes(self, node):
-        """Allow bytes literals without restrictions.
+        def visit_Num(self, node):
+            """Allow integer numbers without restrictions.
 
-        Bytes is Python 3 only.
-        Replaced by Constant in Python 3.8.
-        """
-        return self.node_contents_visit(node)
+            Replaced by Constant in Python 3.8.
+            """
+            return self.node_contents_visit(node)
+
+        def visit_Str(self, node):
+            """Allow string literals without restrictions.
+
+            Replaced by Constant in Python 3.8.
+            """
+            return self.node_contents_visit(node)
+
+        def visit_Bytes(self, node):
+            """Allow bytes literals without restrictions.
+
+            Bytes is Python 3 only.
+            Replaced by Constant in Python 3.8.
+            """
+            return self.node_contents_visit(node)
+
+        def visit_Ellipsis(self, node):
+            """Deny using `...`.
+
+            Ellipsis exists only in Python 3.
+            Replaced by Constant in Python 3.8.
+            """
+            return self.not_allowed(node)
+
+        def visit_NameConstant(self, node):
+            """Allow constant literals (True, False, None) without ...
+
+            restrictions.
+
+            Replaced by Constant in Python 3.8.
+            """
+            return self.node_contents_visit(node)
 
     def visit_List(self, node):
         """Allow list literals without restrictions."""
@@ -587,38 +626,6 @@ def visit_JoinedStr(self, node):
         """Allow joined string without restrictions."""
         return self.node_contents_visit(node)
 
-    def visit_Constant(self, node):
-        """Allow constant literals with restriction for Ellipsis.
-
-        Constant replaces Num, Str, Bytes, NameConstant and Ellipsis in
-        Python 3.8+.
-        :see: https://docs.python.org/dev/whatsnew/3.8.html#deprecated
-        """
-        if node.value is Ellipsis:
-            # Deny using `...`.
-            # Special handling necessary as ``self.not_allowed(node)``
-            # would return the Error Message:
-            # 'Constant statements are not allowed.'
-            # which is only partial true.
-            self.error(node, 'Ellipsis statements are not allowed.')
-            return
-        return self.node_contents_visit(node)
-
-    def visit_Ellipsis(self, node):
-        """Deny using `...`.
-
-        Ellipsis is exists only in Python 3.
-        Replaced by Constant in Python 3.8.
-        """
-        return self.not_allowed(node)
-
-    def visit_NameConstant(self, node):
-        """Allow constant literals (True, False, None) without restrictions.
-
-        Replaced by Constant in Python 3.8.
-        """
-        return self.node_contents_visit(node)
-
     # ast for Variables
 
     def visit_Name(self, node):

tox.ini

@@ -51,7 +51,7 @@ commands =
     coverage combine
     coverage html
     coverage report -m --fail-under=100
-depends = py27,py35,py36,py39-datetime,py37,py38,py39,coverage
+depends = py27,py35,py36,py37,py38,py39,py39-datetime,py310,coverage
 
 [testenv:lint]
 basepython = python3
@@ -92,7 +92,7 @@ commands =
     pytest --cov=src --cov=tests --cov-report= {posargs}
     coverage run -a -m sphinx -b doctest -d {envdir}/.cache/doctrees docs {envdir}/.cache/doctest
     coverage html
-    coverage report -m --fail-under=98.9
+    coverage report -m --fail-under=98.7
 
 [coverage:run]
 branch = True