[3.8] bpo-36917: Add default implementation of ast.NodeVisitor.visit_… · python/cpython@522a394 · GitHub
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[3.8] bpo-36917: Add default implementation of ast.NodeVisitor.visit_Constant(). (GH-15490) (GH-15509)
It emits a deprecation warning and calls corresponding method visit_Num(), visit_Str(), etc. (cherry picked from commit c3ea41e)
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‎Doc/library/ast.rst‎

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‎Doc/whatsnew/3.8.rst‎

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@@ -1360,6 +1360,13 @@ Deprecated
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versions. :class:`~ast.Constant` should be used instead.
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(Contributed by Serhiy Storchaka in :issue:`32892`.)
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* :class:`ast.NodeVisitor` methods ``visit_Num()``, ``visit_Str()``,
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``visit_Bytes()``, ``visit_NameConstant()`` and ``visit_Ellipsis()`` are
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deprecated now and will not be called in future Python versions.
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Add the :meth:`~ast.NodeVisitor.visit_Constant` method to handle all
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constant nodes.
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(Contributed by Serhiy Storchaka in :issue:`36917`.)
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* The following functions and methods are deprecated in the :mod:`gettext`
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module: :func:`~gettext.lgettext`, :func:`~gettext.ldgettext`,
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:func:`~gettext.lngettext` and :func:`~gettext.ldngettext`.

‎Lib/ast.py‎

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@@ -360,6 +360,27 @@ def generic_visit(self, node):
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elif isinstance(value, AST):
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self.visit(value)
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def visit_Constant(self, node):
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value = node.value
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type_name = _const_node_type_names.get(type(value))
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if type_name is None:
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for cls, name in _const_node_type_names.items():
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if isinstance(value, cls):
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type_name = name
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break
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if type_name is not None:
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method = 'visit_' + type_name
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try:
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visitor = getattr(self, method)
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except AttributeError:
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pass
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else:
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import warnings
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warnings.warn(f"{method} is deprecated; add visit_Constant",
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PendingDeprecationWarning, 2)
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return visitor(node)
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return self.generic_visit(node)
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class NodeTransformer(NodeVisitor):
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"""
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_const_types_not = {
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Num: (bool,),
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}
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_const_node_type_names = {
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bool: 'NameConstant', # should be before int
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type(None): 'NameConstant',
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int: 'Num',
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float: 'Num',
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complex: 'Num',
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str: 'Str',
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bytes: 'Bytes',
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type(...): 'Ellipsis',
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}

‎Lib/test/test_ast.py‎

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@@ -3,6 +3,7 @@
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import os
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import sys
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import unittest
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import warnings
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import weakref
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from textwrap import dedent
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@@ -1662,6 +1663,56 @@ class C:
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self.assertEqual(ast.get_source_segment(s, cdef.body[0], padded=True), s_method)
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class NodeVisitorTests(unittest.TestCase):
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def test_old_constant_nodes(self):
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class Visitor(ast.NodeVisitor):
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def visit_Num(self, node):
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log.append((node.lineno, 'Num', node.n))
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def visit_Str(self, node):
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log.append((node.lineno, 'Str', node.s))
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def visit_Bytes(self, node):
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log.append((node.lineno, 'Bytes', node.s))
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def visit_NameConstant(self, node):
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log.append((node.lineno, 'NameConstant', node.value))
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def visit_Ellipsis(self, node):
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log.append((node.lineno, 'Ellipsis', ...))
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mod = ast.parse(dedent('''\
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i = 42
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f = 4.25
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c = 4.25j
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s = 'string'
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b = b'bytes'
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t = True
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n = None
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e = ...
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'''))
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visitor = Visitor()
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log = []
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with warnings.catch_warnings(record=True) as wlog:
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warnings.filterwarnings('always', '', PendingDeprecationWarning)
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visitor.visit(mod)
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self.assertEqual(log, [
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(1, 'Num', 42),
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(2, 'Num', 4.25),
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(3, 'Num', 4.25j),
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(4, 'Str', 'string'),
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(5, 'Bytes', b'bytes'),
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(6, 'NameConstant', True),
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(7, 'NameConstant', None),
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(8, 'Ellipsis', ...),
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])
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self.assertEqual([str(w.message) for w in wlog], [
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'visit_Num is deprecated; add visit_Constant',
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'visit_Num is deprecated; add visit_Constant',
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'visit_Num is deprecated; add visit_Constant',
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'visit_Str is deprecated; add visit_Constant',
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'visit_Bytes is deprecated; add visit_Constant',
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'visit_NameConstant is deprecated; add visit_Constant',
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'visit_NameConstant is deprecated; add visit_Constant',
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'visit_Ellipsis is deprecated; add visit_Constant',
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])
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def main():
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if __name__ != '__main__':
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return

‎Misc/NEWS.d/next/Library/2019-08-25-14-56-42.bpo-36917.GBxdw2.rst‎

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