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Merged
serhiy-storchaka merged 16 commits into from
May 8, 2025
Merged

gh-125028: Prohibit placeholders in partial keywords #126062

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8b08ed5
impl
dg-pb Oct 9, 2024
bea722a
📜🤖 Added by blurb_it.
blurb-it[bot] Oct 9, 2024
f346390
Merge remote-tracking branch 'upstream/main' into gh-125028-prohibit-…
dg-pb Oct 17, 2024
c7ee84b
Merge remote-tracking branch 'upstream/main' into gh-125028-prohibit-…
dg-pb Oct 28, 2024
e741a5c
remove news
dg-pb Oct 28, 2024
71e65c3
📜🤖 Added by blurb_it.
blurb-it[bot] Oct 28, 2024
294f189
no loop for check
dg-pb Oct 28, 2024
5abc61e
Idiomatic C
dg-pb Jan 5, 2025
656361b
remove unrelated changes
dg-pb Jan 5, 2025
da4214a
loosen the regex in test
dg-pb Jan 5, 2025
26dded8
improved error message
dg-pb Jan 5, 2025
e8d7521
doc updates
dg-pb Jan 5, 2025
106e6bc
decouple error checking and kw merging + tests
dg-pb Jan 6, 2025
5e151aa
make test meaningful for ANY check
dg-pb Jan 6, 2025
38ff471
Use ALWAYS_EQ instead of ANY
dg-pb Jan 7, 2025
85955d6
comment update
dg-pb Jan 7, 2025
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3 changes: 1 addition & 2 deletions Doc/library/functools.rst
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Expand Up@@ -403,8 +403,7 @@ The :mod:`functools` module defines the following functions:
>>> remove_first_dear(message)
'Hello, dear world!'

:data:`!Placeholder` has no special treatment when used in a keyword
argument to :func:`!partial`.
:data:`!Placeholder` cannot be passed to :func:`!partial` as a keyword argument.

.. versionchanged:: 3.14
Added support for :data:`Placeholder` in positional arguments.
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3 changes: 3 additions & 0 deletions Lib/functools.py
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Expand Up@@ -326,6 +326,9 @@ def _partial_new(cls, func, /, *args, **keywords):
"or a descriptor")
if args and args[-1] is Placeholder:
raise TypeError("trailing Placeholders are not allowed")
for value in keywords.values():
if value is Placeholder:
raise TypeError("Placeholder cannot be passed as a keyword argument")
if isinstance(func, base_cls):
pto_phcount = func._phcount
tot_args = func.args
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19 changes: 19 additions & 0 deletions Lib/test/test_functools.py
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Expand Up@@ -20,6 +20,7 @@
import contextlib
from inspect import Signature

from test.support import ALWAYS_EQ
from test.support import import_helper
from test.support import threading_helper

Expand DownExpand Up@@ -233,6 +234,13 @@ def test_placeholders(self):
actual_args, actual_kwds = p('x', 'y')
self.assertEqual(actual_args, ('x', 0, 'y', 1))
self.assertEqual(actual_kwds,{})
# Checks via `is` and not `eq`
# thus ALWAYS_EQ isn't treated as Placeholder
p = self.partial(capture, ALWAYS_EQ)
actual_args, actual_kwds = p()
self.assertEqual(len(actual_args), 1)
self.assertIs(actual_args[0], ALWAYS_EQ)
self.assertEqual(actual_kwds,{})

def test_placeholders_optimization(self):
PH = self.module.Placeholder
Expand All@@ -249,6 +257,17 @@ def test_placeholders_optimization(self):
self.assertEqual(p2.args, (PH, 0))
self.assertEqual(p2(1), ((1, 0),{}))

def test_placeholders_kw_restriction(self):
PH = self.module.Placeholder
with self.assertRaisesRegex(TypeError, "Placeholder"):
self.partial(capture, a=PH)
# Passes, as checks via `is` and not `eq`
p = self.partial(capture, a=ALWAYS_EQ)
actual_args, actual_kwds = p()
self.assertEqual(actual_args, ())
self.assertEqual(len(actual_kwds), 1)
self.assertIs(actual_kwds['a'], ALWAYS_EQ)

def test_construct_placeholder_singleton(self):
PH = self.module.Placeholder
tp = type(PH)
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1 change: 1 addition & 0 deletions Misc/NEWS.d/next/Library/2024-10-28-06-54-22.gh-issue-125028.GEY8Ws.rst
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@@ -0,0 +1 @@
:data:`functools.Placeholder` cannot be passed to :func:`functools.partial` as a keyword argument.
13 changes: 13 additions & 0 deletions Modules/_functoolsmodule.c
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Expand Up@@ -196,6 +196,19 @@ partial_new(PyTypeObject *type, PyObject *args, PyObject *kw)
return NULL;
}

/* keyword Placeholder prohibition */
if (kw != NULL){
PyObject *key, *val;
Py_ssize_t pos = 0;
while (PyDict_Next(kw, &pos, &key, &val)){
if (val == phold){
PyErr_SetString(PyExc_TypeError,
"Placeholder cannot be passed as a keyword argument");
return NULL;
}
}
}

/* check wrapped function / object */
pto_args = pto_kw = NULL;
int res = PyObject_TypeCheck(func, state->partial_type);
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