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gh-92391: Add __class_getitem__ to csv.DictReader and csv.DictWriter #92393

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Merged
merged 3 commits into from
May 8, 2022
+12 −1
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gh-92391: Add __class_getitem__ to csv.DictReader and csv.DictWriter #92393

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808c603
Add __class_getitem__ to csv.DictReader and csv.DictWriter
cdce8p May 6, 2022
607e5a2
Merge remote-tracking branch 'upstream/main' into csv-class_getitem
cdce8p May 8, 2022
6c15d12
Merge branch 'main' into csv-class_getitem
JelleZijlstra May 8, 2022
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5 changes: 5 additions & 0 deletions Lib/csv.py
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Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,7 @@
"""

import re
import types
from _csv import Error, __version__, writer, reader, register_dialect, \
unregister_dialect, get_dialect, list_dialects, \
field_size_limit, \
Expand Down Expand Up @@ -126,6 +127,8 @@ def __next__(self):
d[key] = self.restval
return d

__class_getitem__ = classmethod(types.GenericAlias)


class DictWriter:
def __init__(self, f, fieldnames, restval="", extrasaction="raise",
Expand Down Expand Up @@ -156,6 +159,8 @@ def writerow(self, rowdict):
def writerows(self, rowdicts):
return self.writer.writerows(map(self._dict_to_list, rowdicts))

__class_getitem__ = classmethod(types.GenericAlias)

# Guard Sniffer's type checking against builds that exclude complex()
try:
complex
Expand Down
4 changes: 3 additions & 1 deletion Lib/test/test_genericalias.py
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Expand Up @@ -11,6 +11,7 @@
from concurrent.futures.thread import _WorkItem
from contextlib import AbstractContextManager, AbstractAsyncContextManager
from contextvars import ContextVar, Token
from csv import DictReader, DictWriter
from dataclasses import Field
from functools import partial, partialmethod, cached_property
from graphlib import TopologicalSorter
Expand Down Expand Up @@ -122,7 +123,8 @@ class BaseTest(unittest.TestCase):
WeakSet, ReferenceType, ref,
ShareableList,
Future, _WorkItem,
Morsel]
Morsel,
DictReader, DictWriter]
if ctypes is not None:
generic_types.extend((ctypes.Array, ctypes.LibraryLoader))
if ValueProxy is not None:
Expand Down
1 change: 1 addition & 0 deletions Misc/ACKS
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Expand Up @@ -1228,6 +1228,7 @@ Alessandro Moura
Pablo Mouzo
Mher Movsisyan
Ruslan Mstoi
Marc Mueller
Valentina Mukhamedzhanova
Michael Mulich
Sape Mullender
Expand Down
3 changes: 3 additions & 0 deletions Misc/NEWS.d/next/Library/2022-05-06-13-00-57.gh-issue-92391.s-Lase.rst
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@@ -0,0 +1,3 @@
Add :meth:`~object.__class_getitem__` to :class:`csv.DictReader` and
:class:`csv.DictWriter`, allowing them to be parameterized at runtime.
Patch by Marc Mueller.