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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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Use typed lru_cache for Literal type
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@uriyyo
uriyyo committed Nov 15, 2020
commit b8a597a7279d54957158473fa5efa4d81884c586
3 changes: 3 additions & 0 deletions Lib/test/test_typing.py
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Original file line number Diff line number Diff line change
Expand Up @@ -560,6 +560,9 @@ def test_no_multiple_subscripts(self):
Literal[1][1]

def test_equal(self):
self.assertNotEqual(Literal[0], Literal[False])
self.assertNotEqual(Literal[True], Literal[1])
self.assertNotEqual(Literal[1], Literal[2])
self.assertNotEqual(Literal[1, True], Literal[1])
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self.assertEqual(Literal[1], Literal[1])
self.assertEqual(Literal[1, 2], Literal[2, 1])
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36 changes: 24 additions & 12 deletions Lib/typing.py
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Expand Up @@ -242,22 +242,27 @@ def _flatten_literal_params(parameters):
_cleanups = []


def _tp_cache(func):
def _tp_cache(typed=False):
"""Internal wrapper caching __getitem__ of generic types with a fallback to
original function for non-hashable arguments.
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"""
cached = functools.lru_cache()(func)
_cleanups.append(cached.cache_clear)
if callable(typed):
return _tp_cache()(typed)

@functools.wraps(func)
def inner(*args, **kwds):
try:
return cached(*args, **kwds)
except TypeError:
pass # All real errors (not unhashable args) are raised below.
return func(*args, **kwds)
return inner
def decorator(func):
cached = functools.lru_cache(typed=typed)(func)
_cleanups.append(cached.cache_clear)

@functools.wraps(func)
def inner(*args, **kwds):
try:
return cached(*args, **kwds)
except TypeError:
pass # All real errors (not unhashable args) are raised below.
return func(*args, **kwds)
return inner

return decorator

def _eval_type(t, globalns, localns, recursive_guard=frozenset()):
"""Evaluate all forward references in the given type t.
Expand Down Expand Up @@ -330,6 +335,13 @@ def __subclasscheck__(self, cls):
def __getitem__(self, parameters):
return self._getitem(self, parameters)


class _LiteralSpecialForm(_SpecialForm, _root=True):
@_tp_cache(typed=True)
def __getitem__(self, parameters):
return self._getitem(self, parameters)


@_SpecialForm
def Any(self, parameters):
"""Special type indicating an unconstrained type.
Expand Down Expand Up @@ -447,7 +459,7 @@ def Optional(self, parameters):
arg = _type_check(parameters, f"{self} requires a single type.")
return Union[arg, type(None)]

@_SpecialForm
@_LiteralSpecialForm
def Literal(self, parameters):
"""Special typing form to define literal types (a.k.a. value types).

Expand Down