[3.9] bpo-41631: _ast module uses again a global state (GH-21961) (GH-22258)
Partially revert commit ac46eb4ad6662cf6d771b20d8963658b2186c48c:
"bpo-38113: Update the Python-ast.c generator to PEP384 (gh-15957)".
Using a module state per module instance is causing subtle practical
problems.
For example, the Mercurial project replaces the __import__() function
to implement lazy import, whereas Python expected that "import _ast"
always return a fully initialized _ast module.
Add _PyAST_Fini() to clear the state at exit.
The _ast module has no state (set _astmodule.m_size to 0). Remove
astmodule_traverse(), astmodule_clear() and astmodule_free()
functions..
(cherry picked from commit e5fbe0cbd4be99ced5f000ad382208ad2a561c90)
Co-authored-by: Victor Stinner <vstinner@python.org>
diff --git a/Lib/ast.py b/Lib/ast.py
index 65ebd01..d860917 100644
--- a/Lib/ast.py
+++ b/Lib/ast.py
@@ -497,18 +497,20 @@
return node
-# The following code is for backward compatibility.
-# It will be removed in future.
+# If the ast module is loaded more than once, only add deprecated methods once
+if not hasattr(Constant, 'n'):
+ # The following code is for backward compatibility.
+ # It will be removed in future.
-def _getter(self):
- """Deprecated. Use value instead."""
- return self.value
+ def _getter(self):
+ """Deprecated. Use value instead."""
+ return self.value
-def _setter(self, value):
- self.value = value
+ def _setter(self, value):
+ self.value = value
-Constant.n = property(_getter, _setter)
-Constant.s = property(_getter, _setter)
+ Constant.n = property(_getter, _setter)
+ Constant.s = property(_getter, _setter)
class _ABC(type):
@@ -600,14 +602,19 @@
def __new__(cls, dims=(), **kwargs):
return Tuple(list(dims), Load(), **kwargs)
-def _dims_getter(self):
- """Deprecated. Use elts instead."""
- return self.elts
+# If the ast module is loaded more than once, only add deprecated methods once
+if not hasattr(Tuple, 'dims'):
+ # The following code is for backward compatibility.
+ # It will be removed in future.
-def _dims_setter(self, value):
- self.elts = value
+ def _dims_getter(self):
+ """Deprecated. Use elts instead."""
+ return self.elts
-Tuple.dims = property(_dims_getter, _dims_setter)
+ def _dims_setter(self, value):
+ self.elts = value
+
+ Tuple.dims = property(_dims_getter, _dims_setter)
class Suite(mod):
"""Deprecated AST node class. Unused in Python 3."""