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bpo-42345: Fix three issues with typing.Literal parameters by uriyyo · Pull Request #23294 · python/cpython · GitHub
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bpo-42345: Fix three issues with typing.Literal parameters #23294

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Merged
miss-islington merged 8 commits into from
Nov 17, 2020
Merged

bpo-42345: Fix three issues with typing.Literal parameters #23294

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03637e2
bpo-42345: Literal equality no longer depends on order of arguments
uriyyo Nov 15, 2020
4fbf590
Use value and type for Literal equality check
uriyyo Nov 15, 2020
ea06129
Return Literal equality test
uriyyo Nov 15, 2020
b8a597a
Use typed lru_cache for Literal type
uriyyo Nov 15, 2020
19b0952
Update Misc/NEWS
uriyyo Nov 15, 2020
9d2187a
Update signature of _tp_cache function
uriyyo Nov 16, 2020
942dece
Add Literal arguments deduplication
uriyyo Nov 16, 2020
f653d68
Update News. Add tests for Literal.__args__
uriyyo Nov 17, 2020
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10 changes: 10 additions & 0 deletions Lib/test/test_typing.py
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Original file line number Diff line number Diff line change
Expand Up @@ -559,6 +559,16 @@ def test_no_multiple_subscripts(self):
with self.assertRaises(TypeError):
Literal[1][1]

def test_equal(self):
self.assertEqual(Literal[1], Literal[1])
self.assertEqual(Literal[1, 2], Literal[2, 1])
self.assertEqual(Literal[1, 2, 3], Literal[1, 2, 3, 3])

def test_flatten(self):
self.assertEqual(Literal[Literal[1], Literal[2], Literal[3]], Literal[1, 2, 3])
self.assertEqual(Literal[Literal[1, 2], 3], Literal[1, 2, 3])
self.assertEqual(Literal[Literal[1, 2, 3]], Literal[1, 2, 3])
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XK = TypeVar('XK', str, bytes)
XV = TypeVar('XV')
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32 changes: 31 additions & 1 deletion Lib/typing.py
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Expand Up @@ -228,6 +228,17 @@ def _remove_dups_flatten(parameters):
return tuple(params)


def _flatten_literal_params(parameters):
"""An internal helper for Literal creation: flatten Literals among parameters"""
params = []
for p in parameters:
if isinstance(p, _LiteralGenericAlias):
params.extend(p.__args__)
else:
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params.append(p)
return tuple(params)


_cleanups = []


Expand Down Expand Up @@ -460,7 +471,11 @@ def open_helper(file: str, mode: MODE) -> str:
"""
# There is no '_type_check' call because arguments to Literal[...] are
# values, not types.
return _GenericAlias(self, parameters)
if not isinstance(parameters, tuple):
parameters = (parameters,)

parameters = _flatten_literal_params(parameters)
return _LiteralGenericAlias(self, parameters)


@_SpecialForm
Expand Down Expand Up @@ -930,6 +945,21 @@ def __subclasscheck__(self, cls):
return True


def _value_and_type_iter(parameters):
return ((p, type(p)) for p in parameters)


class _LiteralGenericAlias(_GenericAlias, _root=True):

def __eq__(self, other):
if not isinstance(other, _LiteralGenericAlias):
return NotImplemented

return set(_value_and_type_iter(self.__args__)) == set(_value_and_type_iter(other.__args__))
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def __hash__(self):
return hash(tuple(_value_and_type_iter(self.__args__)))


class Generic:
"""Abstract base class for generic types.
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1 change: 1 addition & 0 deletions Misc/ACKS
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Original file line number Diff line number Diff line change
Expand Up @@ -861,6 +861,7 @@ Jan Kanis
Rafe Kaplan
Jacob Kaplan-Moss
Allison Kaptur
Yurii Karabas
Janne Karila
Per Øyvind Karlsen
Anton Kasyanov
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2 changes: 2 additions & 0 deletions Misc/NEWS.d/next/Library/2020-11-15-15-23-34.bpo-42345.hiIR7x.rst
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@@ -0,0 +1,2 @@
Literal equality no longer depends on order of arguments. Patch provided by
Yurii Karabas.