https://github.com/python/cpython/commit/abb90ba46c597a1b192027e914ad312dd62d2462
commit: abb90ba46c597a1b192027e914ad312dd62d2462
branch: main
author: Sayandip Dutta <[email protected]>
committer: erlend-aasland <[email protected]>
date: 2024-11-12T13:11:58Z
summary:
gh-125916: Allow functools.reduce() 'initial' to be a keyword argument (#125917)
files:
A Misc/NEWS.d/next/Library/2024-10-24-13-40-20.gh-issue-126916.MAgz6D.rst
M Doc/library/functools.rst
M Doc/whatsnew/3.14.rst
M Lib/functools.py
M Lib/test/test_functools.py
M Misc/ACKS
M Modules/_functoolsmodule.c
M Modules/clinic/_functoolsmodule.c.h
diff --git a/Doc/library/functools.rst b/Doc/library/functools.rst
index e26a2226aa947a..a9aceee4170004 100644
--- a/Doc/library/functools.rst
+++ b/Doc/library/functools.rst
@@ -453,7 +453,7 @@ The :mod:`functools` module defines the following functions:
.. versionadded:: 3.4
-.. function:: reduce(function, iterable[, initial], /)
+.. function:: reduce(function, iterable, /[, initial])
Apply *function* of two arguments cumulatively to the items of *iterable*,
from
left to right, so as to reduce the iterable to a single value. For example,
@@ -468,7 +468,7 @@ The :mod:`functools` module defines the following functions:
initial_missing = object()
- def reduce(function, iterable, initial=initial_missing, /):
+ def reduce(function, iterable, /, initial=initial_missing):
it = iter(iterable)
if initial is initial_missing:
value = next(it)
@@ -481,6 +481,9 @@ The :mod:`functools` module defines the following functions:
See :func:`itertools.accumulate` for an iterator that yields all
intermediate
values.
+ .. versionchanged:: next
+ *initial* is now supported as a keyword argument.
+
.. decorator:: singledispatch
Transform a function into a :term:`single-dispatch <single
diff --git a/Doc/whatsnew/3.14.rst b/Doc/whatsnew/3.14.rst
index 9c032637d651ec..66f8c432aead61 100644
--- a/Doc/whatsnew/3.14.rst
+++ b/Doc/whatsnew/3.14.rst
@@ -320,6 +320,11 @@ functools
to reserve a place for positional arguments.
(Contributed by Dominykas Grigonis in :gh:`119127`.)
+* Allow the *initial* parameter of :func:`functools.reduce` to be passed
+ as a keyword argument.
+ (Contributed by Sayandip Dutta in :gh:`125916`.)
+
+
getopt
------
diff --git a/Lib/functools.py b/Lib/functools.py
index 27abd622a8cff1..bde0a3e95b8275 100644
--- a/Lib/functools.py
+++ b/Lib/functools.py
@@ -236,7 +236,7 @@ def __ge__(self, other):
def reduce(function, sequence, initial=_initial_missing):
"""
- reduce(function, iterable[, initial], /) -> value
+ reduce(function, iterable, /[, initial]) -> value
Apply a function of two arguments cumulatively to the items of an
iterable, from left to right.
diff --git a/Lib/test/test_functools.py b/Lib/test/test_functools.py
index d590af090abc6e..6d60f6941c4c5d 100644
--- a/Lib/test/test_functools.py
+++ b/Lib/test/test_functools.py
@@ -1005,6 +1005,29 @@ def __getitem__(self, i):
d = {"one": 1, "two": 2, "three": 3}
self.assertEqual(self.reduce(add, d), "".join(d.keys()))
+ # test correctness of keyword usage of `initial` in `reduce`
+ def test_initial_keyword(self):
+ def add(x, y):
+ return x + y
+ self.assertEqual(
+ self.reduce(add, ['a', 'b', 'c'], ''),
+ self.reduce(add, ['a', 'b', 'c'], initial=''),
+ )
+ self.assertEqual(
+ self.reduce(add, [['a', 'c'], [], ['d', 'w']], []),
+ self.reduce(add, [['a', 'c'], [], ['d', 'w']], initial=[]),
+ )
+ self.assertEqual(
+ self.reduce(lambda x, y: x*y, range(2,8), 1),
+ self.reduce(lambda x, y: x*y, range(2,8), initial=1),
+ )
+ self.assertEqual(
+ self.reduce(lambda x, y: x*y, range(2,21), 1),
+ self.reduce(lambda x, y: x*y, range(2,21), initial=1),
+ )
+ self.assertRaises(TypeError, self.reduce, add, [0, 1], initial="")
+ self.assertEqual(self.reduce(42, "", initial="1"), "1") # func is
never called with one item
+
@unittest.skipUnless(c_functools, 'requires the C _functools module')
class TestReduceC(TestReduce, unittest.TestCase):
diff --git a/Misc/ACKS b/Misc/ACKS
index 6b5d7bf80cee6d..dce322fc867743 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -485,6 +485,7 @@ Luke Dunstan
Virgil Dupras
Bruno Dupuis
Andy Dustman
+Sayandip Dutta
Gary Duzan
Eugene Dvurechenski
Karmen Dykstra
diff --git
a/Misc/NEWS.d/next/Library/2024-10-24-13-40-20.gh-issue-126916.MAgz6D.rst
b/Misc/NEWS.d/next/Library/2024-10-24-13-40-20.gh-issue-126916.MAgz6D.rst
new file mode 100644
index 00000000000000..cbe2fc166ba6af
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2024-10-24-13-40-20.gh-issue-126916.MAgz6D.rst
@@ -0,0 +1,2 @@
+Allow the *initial* parameter of :func:`functools.reduce` to be passed as a
keyword argument.
+Patch by Sayandip Dutta.
diff --git a/Modules/_functoolsmodule.c b/Modules/_functoolsmodule.c
index d2afe1a1bea018..5e0cf057dcd1a2 100644
--- a/Modules/_functoolsmodule.c
+++ b/Modules/_functoolsmodule.c
@@ -937,8 +937,8 @@ _functools.reduce
function as func: object
iterable as seq: object
- initial as result: object = NULL
/
+ initial as result: object = NULL
Apply a function of two arguments cumulatively to the items of an iterable,
from left to right.
@@ -953,7 +953,7 @@ calculates ((((1 + 2) + 3) + 4) + 5).
static PyObject *
_functools_reduce_impl(PyObject *module, PyObject *func, PyObject *seq,
PyObject *result)
-/*[clinic end generated code: output=30d898fe1267c79d input=d233c2670cba7f66]*/
+/*[clinic end generated code: output=30d898fe1267c79d input=1511e9a8c38581ac]*/
{
PyObject *args, *it;
diff --git a/Modules/clinic/_functoolsmodule.c.h
b/Modules/clinic/_functoolsmodule.c.h
index 760877928db60d..afd5eb4eb12b78 100644
--- a/Modules/clinic/_functoolsmodule.c.h
+++ b/Modules/clinic/_functoolsmodule.c.h
@@ -69,7 +69,7 @@ _functools_cmp_to_key(PyObject *module, PyObject *const
*args, Py_ssize_t nargs,
}
PyDoc_STRVAR(_functools_reduce__doc__,
-"reduce($module, function, iterable, initial=<unrepresentable>, /)\n"
+"reduce($module, function, iterable, /, initial=<unrepresentable>)\n"
"--\n"
"\n"
"Apply a function of two arguments cumulatively to the items of an iterable,
from left to right.\n"
@@ -82,30 +82,59 @@ PyDoc_STRVAR(_functools_reduce__doc__,
"calculates ((((1 + 2) + 3) + 4) + 5).");
#define _FUNCTOOLS_REDUCE_METHODDEF \
- {"reduce", _PyCFunction_CAST(_functools_reduce), METH_FASTCALL,
_functools_reduce__doc__},
+ {"reduce", _PyCFunction_CAST(_functools_reduce),
METH_FASTCALL|METH_KEYWORDS, _functools_reduce__doc__},
static PyObject *
_functools_reduce_impl(PyObject *module, PyObject *func, PyObject *seq,
PyObject *result);
static PyObject *
-_functools_reduce(PyObject *module, PyObject *const *args, Py_ssize_t nargs)
+_functools_reduce(PyObject *module, PyObject *const *args, Py_ssize_t nargs,
PyObject *kwnames)
{
PyObject *return_value = NULL;
+ #if defined(Py_BUILD_CORE) && !defined(Py_BUILD_CORE_MODULE)
+
+ #define NUM_KEYWORDS 1
+ static struct {
+ PyGC_Head _this_is_not_used;
+ PyObject_VAR_HEAD
+ PyObject *ob_item[NUM_KEYWORDS];
+ } _kwtuple = {
+ .ob_base = PyVarObject_HEAD_INIT(&PyTuple_Type, NUM_KEYWORDS)
+ .ob_item = { &_Py_ID(initial), },
+ };
+ #undef NUM_KEYWORDS
+ #define KWTUPLE (&_kwtuple.ob_base.ob_base)
+
+ #else // !Py_BUILD_CORE
+ # define KWTUPLE NULL
+ #endif // !Py_BUILD_CORE
+
+ static const char * const _keywords[] = {"", "", "initial", NULL};
+ static _PyArg_Parser _parser = {
+ .keywords = _keywords,
+ .fname = "reduce",
+ .kwtuple = KWTUPLE,
+ };
+ #undef KWTUPLE
+ PyObject *argsbuf[3];
+ Py_ssize_t noptargs = nargs + (kwnames ? PyTuple_GET_SIZE(kwnames) : 0) -
2;
PyObject *func;
PyObject *seq;
PyObject *result = NULL;
- if (!_PyArg_CheckPositional("reduce", nargs, 2, 3)) {
+ args = _PyArg_UnpackKeywords(args, nargs, NULL, kwnames, &_parser,
+ /*minpos*/ 2, /*maxpos*/ 3, /*minkw*/ 0, /*varpos*/ 0, argsbuf);
+ if (!args) {
goto exit;
}
func = args[0];
seq = args[1];
- if (nargs < 3) {
- goto skip_optional;
+ if (!noptargs) {
+ goto skip_optional_pos;
}
result = args[2];
-skip_optional:
+skip_optional_pos:
return_value = _functools_reduce_impl(module, func, seq, result);
exit:
@@ -159,4 +188,4 @@ _functools__lru_cache_wrapper_cache_clear(PyObject *self,
PyObject *Py_UNUSED(ig
return return_value;
}
-/*[clinic end generated code: output=0c3df7e5131200b7 input=a9049054013a1b77]*/
+/*[clinic end generated code: output=e6edcc01f0720daf input=a9049054013a1b77]*/
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