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bpo-39942:Fix TypeVar fails when missing __name__ #19616

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Merged
ilevkivskyi merged 2 commits into from
Apr 20, 2020
Merged

bpo-39942:Fix TypeVar fails when missing __name__ #19616

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59fde6d
Fix `TypeVar` fails when missing `__name__`
hongweipeng Apr 20, 2020
4387dfe
code review
hongweipeng Apr 20, 2020
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@hongweipeng
hongweipeng committed Apr 20, 2020
commit 4387dfe2b66bb7955fc4fe2e3489ee727dbd2945
8 changes: 4 additions & 4 deletions Lib/test/test_typing.py
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Expand Up @@ -222,10 +222,10 @@ def test_bound_errors(self):
TypeVar('X', str, float, bound=Employee)

def test_missing__name__(self):
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@remilapeyre remilapeyre Apr 20, 2020

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    def test_missing__name__(self):
        # See bpo-39942
        code = ("import typing\n"
                "T = typing.TypeVar('T')\n"
                )
        exec(code, {})

would be more like the other tests

code = """if 1:
import typing
T = typing.TypeVar("T")
"""
# See bpo-39942
code = ("import typing\n"
"T = typing.TypeVar('T')\n"
)
exec(code, {})

def test_no_bivariant(self):
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6 changes: 3 additions & 3 deletions Lib/typing.py
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Expand Up @@ -608,10 +608,10 @@ def __init__(self, name, *constraints, bound=None,
self.__bound__ = None
try:
def_mod = sys._getframe(1).f_globals.get('__name__', '__main__') # for pickling
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@remilapeyre remilapeyre Apr 20, 2020

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I don't think it's safe to assume __name__ is __main__ when it's not defined here. I think other classes like enums make the class unpickable when __name__ cannot be determined.

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@ilevkivskyi ilevkivskyi Apr 20, 2020

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I think '__main__' is fine. By the way a similar code is used by TypedDict and NamedTuple, so you can copy it here. Or maybe it would even make sense to factor this out in an internal helper function doing this:

    try:
        module = sys._getframe(1).f_globals.get('__name__', '__main__')
    except (AttributeError, ValueError):
        module = None

if def_mod != 'typing':
self.__module__ = def_mod
except (AttributeError, ValueError):
pass
def_mod = None
if def_mod != 'typing':
self.__module__ = def_mod

def __repr__(self):
if self.__covariant__:
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2 changes: 2 additions & 0 deletions Misc/NEWS.d/next/Library/2020-04-20-20-16-02.bpo-39942.NvGnTc.rst
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Original file line number Diff line number Diff line change
@@ -0,0 +1,2 @@
Set "__main__" as the default module name when "__name__" is missing in
:class:`typing.TypeVar`. Patch by Weipeng Hong.