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mvanhornmvanhorn
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Address vstinner review: frozendict wrapper, types.NoneType, doctest
1. Restore frozendict() wrapper for _CROSS_LANGUAGE_HINTS table (lost during the isinstance() refactor in e2c12ec). Convert inner lists to tuples for consistency with immutable container. 2. Replace type(None) with types.NoneType per review. 3. Replace contrived None.keys() doctest with a realistic example: lst = [3, 1, 2].sort() followed by lst.pop(), showing the common "method returned None" mistake vstinner suggested.
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Lines changed: 45 additions & 43 deletions

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‎Doc/whatsnew/3.15.rst‎

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@@ -457,15 +457,17 @@ Improved error messages
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...
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AttributeError: 'tuple' object has no attribute 'append'. Did you mean to use a 'list' object?
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When a common method is called on ``None``, the hint suggests the type
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the user likely expected:
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When a common method is called on ``None`` (often because a method like
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:meth:`list.sort` returned ``None`` instead of the expected object), the
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hint suggests the type the user likely expected:
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.. doctest::
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>>> None.keys() # doctest: +ELLIPSIS
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>>> lst = [3, 1, 2].sort()
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>>> lst.pop() # doctest: +ELLIPSIS
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Traceback (most recent call last):
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...
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AttributeError: 'NoneType' object has no attribute 'keys'. Did you expect a 'dict'?
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AttributeError: 'NoneType' object has no attribute 'pop'. Did you expect a 'list' or 'dict'?
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These hints also work for subclasses of builtin types.
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‎Lib/traceback.py‎

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@@ -1673,55 +1673,55 @@ def print(self, *, file=None, chain=True, **kwargs):
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# If is_raw is True, the suggestion is rendered as-is.
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#
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# See https://github.com/python/cpython/issues/146406.
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_CROSS_LANGUAGE_HINTS = {
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_CROSS_LANGUAGE_HINTS = frozendict({
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# list -- JavaScript/Ruby equivalents
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"push": [(list, "append", False)],
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"concat": [(list, "extend", False)],
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"push": ((list, "append", False),),
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"concat": ((list, "extend", False),),
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# list -- Java/C# equivalents
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"addAll": [(list, "extend", False)],
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"contains": [(list, "Use 'x in list'.", True)],
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"addAll": ((list, "extend", False),),
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"contains": ((list, "Use 'x in list'.", True),),
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# list -- wrong-type suggestion (user expected a set)
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"add": [(list, "Did you mean to use a 'set' object?", True),
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(frozenset, "Did you mean to use a 'set' object?", True)],
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"add": ((list, "Did you mean to use a 'set' object?", True),
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(frozenset, "Did you mean to use a 'set' object?", True)),
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# str -- JavaScript equivalents
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"toUpperCase": [(str, "upper", False)],
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"toLowerCase": [(str, "lower", False)],
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"trimStart": [(str, "lstrip", False)],
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"trimEnd": [(str, "rstrip", False)],
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"toUpperCase": ((str, "upper", False),),
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"toLowerCase": ((str, "lower", False),),
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"trimStart": ((str, "lstrip", False),),
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"trimEnd": ((str, "rstrip", False),),
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# dict -- Java/JavaScript equivalents
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"keySet": [(dict, "keys", False)],
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"entrySet": [(dict, "items", False)],
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"entries": [(dict, "items", False)],
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"putAll": [(dict, "update", False)],
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"put": [(dict, "Use d[k] = v.", True)],
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"keySet": ((dict, "keys", False),),
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"entrySet": ((dict, "items", False),),
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"entries": ((dict, "items", False),),
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"putAll": ((dict, "update", False),),
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"put": ((dict, "Use d[k] = v.", True),),
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# tuple -- mutable method on immutable type (user expected a list)
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"append": [(tuple, "Did you mean to use a 'list' object?", True)],
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"extend": [(tuple, "Did you mean to use a 'list' object?", True)],
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"insert": [(tuple, "Did you mean to use a 'list' object?", True)],
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"remove": [(tuple, "Did you mean to use a 'list' object?", True),
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(frozenset, "Did you mean to use a 'set' object?", True)],
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"append": ((tuple, "Did you mean to use a 'list' object?", True),),
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"extend": ((tuple, "Did you mean to use a 'list' object?", True),),
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"insert": ((tuple, "Did you mean to use a 'list' object?", True),),
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"remove": ((tuple, "Did you mean to use a 'list' object?", True),
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(frozenset, "Did you mean to use a 'set' object?", True)),
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# frozenset -- mutable method on immutable type (user expected a set)
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"discard": [(frozenset, "Did you mean to use a 'set' object?", True)],
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"discard": ((frozenset, "Did you mean to use a 'set' object?", True),),
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# frozendict -- mutable method on immutable type (user expected a dict)
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"update": [(frozenset, "Did you mean to use a 'set' object?", True),
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(frozendict, "Did you mean to use a 'dict' object?", True)],
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"update": ((frozenset, "Did you mean to use a 'set' object?", True),
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(frozendict, "Did you mean to use a 'dict' object?", True)),
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# float -- bitwise operators belong to int
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"__or__": [(float, "Did you mean to use an 'int' object? Bitwise operators are not supported by 'float'.", True)],
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"__and__": [(float, "Did you mean to use an 'int' object? Bitwise operators are not supported by 'float'.", True)],
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"__xor__": [(float, "Did you mean to use an 'int' object? Bitwise operators are not supported by 'float'.", True)],
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"__lshift__": [(float, "Did you mean to use an 'int' object? Bitwise operators are not supported by 'float'.", True)],
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"__rshift__": [(float, "Did you mean to use an 'int' object? Bitwise operators are not supported by 'float'.", True)],
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"__or__": ((float, "Did you mean to use an 'int' object? Bitwise operators are not supported by 'float'.", True),),
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"__and__": ((float, "Did you mean to use an 'int' object? Bitwise operators are not supported by 'float'.", True),),
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"__xor__": ((float, "Did you mean to use an 'int' object? Bitwise operators are not supported by 'float'.", True),),
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"__lshift__": ((float, "Did you mean to use an 'int' object? Bitwise operators are not supported by 'float'.", True),),
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"__rshift__": ((float, "Did you mean to use an 'int' object? Bitwise operators are not supported by 'float'.", True),),
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# NoneType -- common methods tried on None (got None instead of expected type)
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"keys": [(type(None), "Did you expect a 'dict'?", True)],
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"values": [(type(None), "Did you expect a 'dict'?", True)],
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"items": [(type(None), "Did you expect a 'dict'?", True)],
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"upper": [(type(None), "Did you expect a 'str'?", True)],
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"lower": [(type(None), "Did you expect a 'str'?", True)],
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"strip": [(type(None), "Did you expect a 'str'?", True)],
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"split": [(type(None), "Did you expect a 'str'?", True)],
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"sort": [(type(None), "Did you expect a 'list'?", True)],
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"pop": [(type(None), "Did you expect a 'list' or 'dict'?", True)],
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}
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"keys": ((types.NoneType, "Did you expect a 'dict'?", True),),
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"values": ((types.NoneType, "Did you expect a 'dict'?", True),),
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"items": ((types.NoneType, "Did you expect a 'dict'?", True),),
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"upper": ((types.NoneType, "Did you expect a 'str'?", True),),
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"lower": ((types.NoneType, "Did you expect a 'str'?", True),),
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"strip": ((types.NoneType, "Did you expect a 'str'?", True),),
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"split": ((types.NoneType, "Did you expect a 'str'?", True),),
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"sort": ((types.NoneType, "Did you expect a 'list'?", True),),
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"pop": ((types.NoneType, "Did you expect a 'list' or 'dict'?", True),),
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})
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def _substitution_cost(ch_a, ch_b):

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