From e1c5b001577e938e7419d444bdf089c4c4187790 Mon Sep 17 00:00:00 2001
From: Dong-hee Na <donghee.na92@gmail.com>
Date: Sun, 1 Sep 2019 14:41:29 +0900
Subject: [PATCH 01/20] bpo-24416: Return a namedtuple from date.isocalendar()

---
 Doc/library/datetime.rst                      | 10 ++--
 Doc/whatsnew/3.9.rst                          |  8 ++++
 Lib/datetime.py                               | 10 +++-
 Lib/test/datetimetester.py                    | 10 +++-
 .../2019-09-01-15-17-49.bpo-24416.G8Ww1U.rst  |  4 ++
 Modules/_datetimemodule.c                     | 47 ++++++++++++++++++-
 6 files changed, 81 insertions(+), 8 deletions(-)
 create mode 100644 Misc/NEWS.d/next/Library/2019-09-01-15-17-49.bpo-24416.G8Ww1U.rst

diff --git a/Doc/library/datetime.rst b/Doc/library/datetime.rst
index 2bd25cc4362b26..6292770d4e6427 100644
--- a/Doc/library/datetime.rst
+++ b/Doc/library/datetime.rst
@@ -670,7 +670,7 @@ Instance methods:
 
 .. method:: date.isocalendar()
 
-   Return a 3-tuple, (ISO year, ISO week number, ISO weekday).
+   Return a 3-namedtuple, (ISO year, ISO week number, ISO weekday).
 
    The ISO calendar is a widely used variant of the Gregorian calendar. [#]_
 
@@ -688,6 +688,10 @@ Instance methods:
        >>> date(2004, 1, 4).isocalendar()
        (2004, 1, 7)
 
+   .. versionchanged:: 3.9
+      Result changed from a tuple to a namedtuple.
+      It can't be unpickled in previous versions.
+
 .. method:: date.isoformat()
 
    Return a string representing the date in ISO 8601 format, ``YYYY-MM-DD``::
@@ -1399,8 +1403,8 @@ Instance methods:
 
 .. method:: datetime.isocalendar()
 
-   Return a 3-tuple, (ISO year, ISO week number, ISO weekday). The same as
-   ``self.date().isocalendar()``.
+   Return a 3-namedtuple, (ISO year, ISO week number, ISO weekday).
+   The same as ``self.date().isocalendar()``.
 
 
 .. method:: datetime.isoformat(sep='T', timespec='auto')
diff --git a/Doc/whatsnew/3.9.rst b/Doc/whatsnew/3.9.rst
index 7cf49bfbb93f94..706e171f53b979 100644
--- a/Doc/whatsnew/3.9.rst
+++ b/Doc/whatsnew/3.9.rst
@@ -145,6 +145,14 @@ Add :func:`curses.get_escdelay`, :func:`curses.set_escdelay`,
 :func:`curses.get_tabsize`, and :func:`curses.set_tabsize` functions.
 (Contributed by Anthony Sottile in :issue:`38312`.)
 
+datetime
+--------
+The :meth:`~datetime.date.isocalendar()` of :class:`datetime.date`
+and :meth:`~datetime.datetime.isocalendar()` of :class:`datetime.datetime`
+methods now returns a :func:`~collections.namedtuple` instead of a :class:`tuple`.
+It can't be unpickled in previous versions.
+(Contributed by Dong-hee Na in :issue:`24416`.)
+
 fcntl
 -----
 
diff --git a/Lib/datetime.py b/Lib/datetime.py
index 67555191d02c18..dc402a150ea534 100644
--- a/Lib/datetime.py
+++ b/Lib/datetime.py
@@ -12,6 +12,9 @@
 import math as _math
 import sys
 
+from collections import namedtuple
+
+
 def _cmp(x, y):
     return 0 if x == y else 1 if x > y else -1
 
@@ -1095,7 +1098,7 @@ def isoweekday(self):
         return self.toordinal() % 7 or 7
 
     def isocalendar(self):
-        """Return a 3-tuple containing ISO year, week number, and weekday.
+        """Return a 3-named tuple containing ISO year, week number, and weekday.
 
         The first ISO week of the year is the (Mon-Sun) week
         containing the year's first Thursday; everything else derives
@@ -1120,7 +1123,7 @@ def isocalendar(self):
             if today >= _isoweek1monday(year+1):
                 year += 1
                 week = 0
-        return year, week+1, day+1
+        return IsoCalendarDate(year, week+1, day+1)
 
     # Pickle support.
 
@@ -1559,6 +1562,9 @@ def __reduce__(self):
 time.max = time(23, 59, 59, 999999)
 time.resolution = timedelta(microseconds=1)
 
+IsoCalendarDate = namedtuple('IsoCalendarDate', 'year week weekday')
+
+
 class datetime(date):
     """datetime(year, month, day[, hour[, minute[, second[, microsecond[,tzinfo]]]]])
 
diff --git a/Lib/test/datetimetester.py b/Lib/test/datetimetester.py
index 42e2cecaeb724e..b57f8a32322262 100644
--- a/Lib/test/datetimetester.py
+++ b/Lib/test/datetimetester.py
@@ -76,7 +76,8 @@ def test_name_cleanup(self):
         names = set(name for name in dir(datetime)
                     if not name.startswith('__') and not name.endswith('__'))
         allowed = set(['MAXYEAR', 'MINYEAR', 'date', 'datetime',
-                       'datetime_CAPI', 'time', 'timedelta', 'timezone',
+                       'datetime_CAPI', 'IsoCalendarDate', 'namedtuple',
+                       'time', 'timedelta', 'timezone',
                        'tzinfo', 'sys'])
         self.assertEqual(names - allowed, set([]))
 
@@ -1369,6 +1370,13 @@ def test_isocalendar(self):
             d = self.theclass(2010, 1, 4+i)
             self.assertEqual(d.isocalendar(), (2010, 1, i+1))
 
+    def test_isocalendar_named(self):
+        d = self.theclass(2008, 12, 3)
+        t = d.isocalendar()
+        self.assertEqual(t.year, 2008)
+        self.assertEqual(t.week, 49)
+        self.assertEqual(t.weekday, 3)
+
     def test_iso_long_years(self):
         # Calculate long ISO years and compare to table from
         # http://www.phys.uu.nl/~vgent/calendar/isocalendar.htm
diff --git a/Misc/NEWS.d/next/Library/2019-09-01-15-17-49.bpo-24416.G8Ww1U.rst b/Misc/NEWS.d/next/Library/2019-09-01-15-17-49.bpo-24416.G8Ww1U.rst
new file mode 100644
index 00000000000000..7a0d8ae8558a1c
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2019-09-01-15-17-49.bpo-24416.G8Ww1U.rst
@@ -0,0 +1,4 @@
+The :meth:`~datetime.date.isocalendar()` of :class:`datetime.date` and
+:meth:`~datetime.datetime.isocalendar()` of :class:`datetime.datetime`
+methods now returns a :func:`~collections.namedtuple` instead of a
+:class:`tuple`. It can't be unpickled in previous versions.
diff --git a/Modules/_datetimemodule.c b/Modules/_datetimemodule.c
index c1b24073436e63..3f5cbb90d15581 100644
--- a/Modules/_datetimemodule.c
+++ b/Modules/_datetimemodule.c
@@ -3225,6 +3225,26 @@ date_isoweekday(PyDateTime_Date *self, PyObject *Py_UNUSED(ignored))
     return PyLong_FromLong(dow + 1);
 }
 
+static PyStructSequence_Field struct_iso_calendar_date_fields[] = {
+    {"year", "year, for example, 1993"},
+    {"week", "week, range [1, 53]"},
+    {"weekday", "week day, range [1, 7]"},
+    {0}
+};
+
+static PyStructSequence_Desc struct_iso_calendar_date_desc = {
+    "datetime.IsoCalendarDate",
+    "The result of date.isocalendar() or datetime.isocalendar().\n\n"
+    "This object may be accessed either as a tuple of\n"
+    "  (year,week, weekday)\n"
+    "or via the object attributes as named in the above tuple.",
+    struct_iso_calendar_date_fields,
+    3
+};
+
+static int initialized;
+static PyTypeObject StructIsoCalendarDateType;
+
 static PyObject *
 date_isocalendar(PyDateTime_Date *self, PyObject *Py_UNUSED(ignored))
 {
@@ -3234,6 +3254,9 @@ date_isocalendar(PyDateTime_Date *self, PyObject *Py_UNUSED(ignored))
     int  week;
     int  day;
 
+    PyObject* v = PyStructSequence_New(&StructIsoCalendarDateType);
+    if (!v) return NULL;
+
     week = divmod(today - week1_monday, 7, &day);
     if (week < 0) {
         --year;
@@ -3244,7 +3267,16 @@ date_isocalendar(PyDateTime_Date *self, PyObject *Py_UNUSED(ignored))
         ++year;
         week = 0;
     }
-    return Py_BuildValue("iii", year, week + 1, day + 1);
+
+    PyStructSequence_SET_ITEM(v, 0, PyLong_FromLong(year));
+    PyStructSequence_SET_ITEM(v, 1, PyLong_FromLong(week + 1));
+    PyStructSequence_SET_ITEM(v, 2, PyLong_FromLong(day + 1));
+
+    if (PyErr_Occurred()) {
+        Py_XDECREF(v);
+        return NULL;
+    }
+    return v;
 }
 
 /* Miscellaneous methods. */
@@ -3383,7 +3415,7 @@ static PyMethodDef date_methods[] = {
      PyDoc_STR("Return time tuple, compatible with time.localtime().")},
 
     {"isocalendar", (PyCFunction)date_isocalendar,  METH_NOARGS,
-     PyDoc_STR("Return a 3-tuple containing ISO year, week number, and "
+     PyDoc_STR("Return a 3-named tuple containing ISO year, week number, and "
                "weekday.")},
 
     {"isoformat",   (PyCFunction)date_isoformat,        METH_NOARGS,
@@ -6516,6 +6548,17 @@ PyInit__datetime(void)
     PyModule_AddIntMacro(m, MINYEAR);
     PyModule_AddIntMacro(m, MAXYEAR);
 
+    /* IsoCalendarDate */
+    if (!initialized) {
+        if (PyStructSequence_InitType2(&StructIsoCalendarDateType,
+                                       &struct_iso_calendar_date_desc) < 0) {
+            return NULL;
+        }
+        initialized = 1;
+    }
+    Py_INCREF((PyObject *) &StructIsoCalendarDateType);
+    PyModule_AddObject(m, "IsoCalendarDate", (PyObject *) &StructIsoCalendarDateType);
+
     Py_INCREF(&PyDateTime_DateType);
     PyModule_AddObject(m, "date", (PyObject *) &PyDateTime_DateType);
 

From 309b1f150b2e77a8d2c3ed1645b9013d1a486c52 Mon Sep 17 00:00:00 2001
From: Dong-hee Na <donghee.na92@gmail.com>
Date: Sun, 1 Sep 2019 22:28:33 +0900
Subject: [PATCH 02/20] bpo-24416: Apply code review

---
 Doc/library/datetime.rst                      |  4 ++--
 Lib/datetime.py                               |  7 +++---
 Lib/test/datetimetester.py                    |  1 +
 .../2019-09-01-15-17-49.bpo-24416.G8Ww1U.rst  |  5 ++--
 Modules/_datetimemodule.c                     | 23 +++++++++++--------
 5 files changed, 23 insertions(+), 17 deletions(-)

diff --git a/Doc/library/datetime.rst b/Doc/library/datetime.rst
index 6292770d4e6427..a73c93529ede5d 100644
--- a/Doc/library/datetime.rst
+++ b/Doc/library/datetime.rst
@@ -670,7 +670,7 @@ Instance methods:
 
 .. method:: date.isocalendar()
 
-   Return a 3-namedtuple, (ISO year, ISO week number, ISO weekday).
+   Return a named tuple, (ISO year, ISO week number, ISO weekday).
 
    The ISO calendar is a widely used variant of the Gregorian calendar. [#]_
 
@@ -1403,7 +1403,7 @@ Instance methods:
 
 .. method:: datetime.isocalendar()
 
-   Return a 3-namedtuple, (ISO year, ISO week number, ISO weekday).
+   Return a named tuple, (ISO year, ISO week number, ISO weekday).
    The same as ``self.date().isocalendar()``.
 
 
diff --git a/Lib/datetime.py b/Lib/datetime.py
index dc402a150ea534..571903897c4940 100644
--- a/Lib/datetime.py
+++ b/Lib/datetime.py
@@ -15,6 +15,9 @@
 from collections import namedtuple
 
 
+IsoCalendarDate = namedtuple('IsoCalendarDate', 'year week weekday')
+
+
 def _cmp(x, y):
     return 0 if x == y else 1 if x > y else -1
 
@@ -1098,7 +1101,7 @@ def isoweekday(self):
         return self.toordinal() % 7 or 7
 
     def isocalendar(self):
-        """Return a 3-named tuple containing ISO year, week number, and weekday.
+        """Return a named tuple containing ISO year, week number, and weekday.
 
         The first ISO week of the year is the (Mon-Sun) week
         containing the year's first Thursday; everything else derives
@@ -1562,8 +1565,6 @@ def __reduce__(self):
 time.max = time(23, 59, 59, 999999)
 time.resolution = timedelta(microseconds=1)
 
-IsoCalendarDate = namedtuple('IsoCalendarDate', 'year week weekday')
-
 
 class datetime(date):
     """datetime(year, month, day[, hour[, minute[, second[, microsecond[,tzinfo]]]]])
diff --git a/Lib/test/datetimetester.py b/Lib/test/datetimetester.py
index b57f8a32322262..42dd56206758f3 100644
--- a/Lib/test/datetimetester.py
+++ b/Lib/test/datetimetester.py
@@ -1376,6 +1376,7 @@ def test_isocalendar_named(self):
         self.assertEqual(t.year, 2008)
         self.assertEqual(t.week, 49)
         self.assertEqual(t.weekday, 3)
+        self.assertEqual((2008, 49, 3), t)
 
     def test_iso_long_years(self):
         # Calculate long ISO years and compare to table from
diff --git a/Misc/NEWS.d/next/Library/2019-09-01-15-17-49.bpo-24416.G8Ww1U.rst b/Misc/NEWS.d/next/Library/2019-09-01-15-17-49.bpo-24416.G8Ww1U.rst
index 7a0d8ae8558a1c..4a95fb13ac7d43 100644
--- a/Misc/NEWS.d/next/Library/2019-09-01-15-17-49.bpo-24416.G8Ww1U.rst
+++ b/Misc/NEWS.d/next/Library/2019-09-01-15-17-49.bpo-24416.G8Ww1U.rst
@@ -1,4 +1,3 @@
-The :meth:`~datetime.date.isocalendar()` of :class:`datetime.date` and
-:meth:`~datetime.datetime.isocalendar()` of :class:`datetime.datetime`
-methods now returns a :func:`~collections.namedtuple` instead of a
+The ``isocalendar()`` methods of :class:`datetime.date` and
+:class:`datetime.datetime` now return a :term:`named tuple` instead of a
 :class:`tuple`. It can't be unpickled in previous versions.
diff --git a/Modules/_datetimemodule.c b/Modules/_datetimemodule.c
index 3f5cbb90d15581..068043ff89f8ee 100644
--- a/Modules/_datetimemodule.c
+++ b/Modules/_datetimemodule.c
@@ -3232,12 +3232,15 @@ static PyStructSequence_Field struct_iso_calendar_date_fields[] = {
     {0}
 };
 
+PyDoc_STRVAR(struct_iso_calendar_date__doc__,
+"The result of date.isocalendar() or datetime.isocalendar()\n\n\
+This object may be accessed either as a tuple of\n\
+  ((year, week, weekday)\n\
+or via the object attributes as named in the above tuple.");
+
 static PyStructSequence_Desc struct_iso_calendar_date_desc = {
     "datetime.IsoCalendarDate",
-    "The result of date.isocalendar() or datetime.isocalendar().\n\n"
-    "This object may be accessed either as a tuple of\n"
-    "  (year,week, weekday)\n"
-    "or via the object attributes as named in the above tuple.",
+    struct_iso_calendar_date__doc__,
     struct_iso_calendar_date_fields,
     3
 };
@@ -3254,9 +3257,6 @@ date_isocalendar(PyDateTime_Date *self, PyObject *Py_UNUSED(ignored))
     int  week;
     int  day;
 
-    PyObject* v = PyStructSequence_New(&StructIsoCalendarDateType);
-    if (!v) return NULL;
-
     week = divmod(today - week1_monday, 7, &day);
     if (week < 0) {
         --year;
@@ -3268,12 +3268,17 @@ date_isocalendar(PyDateTime_Date *self, PyObject *Py_UNUSED(ignored))
         week = 0;
     }
 
+    PyObject *v = PyStructSequence_New(&StructIsoCalendarDateType);
+    if (v == NULL) {
+        return NULL;
+    }
+
     PyStructSequence_SET_ITEM(v, 0, PyLong_FromLong(year));
     PyStructSequence_SET_ITEM(v, 1, PyLong_FromLong(week + 1));
     PyStructSequence_SET_ITEM(v, 2, PyLong_FromLong(day + 1));
 
     if (PyErr_Occurred()) {
-        Py_XDECREF(v);
+        Py_DECREF(v);
         return NULL;
     }
     return v;
@@ -3415,7 +3420,7 @@ static PyMethodDef date_methods[] = {
      PyDoc_STR("Return time tuple, compatible with time.localtime().")},
 
     {"isocalendar", (PyCFunction)date_isocalendar,  METH_NOARGS,
-     PyDoc_STR("Return a 3-named tuple containing ISO year, week number, and "
+     PyDoc_STR("Return a named tuple containing ISO year, week number, and "
                "weekday.")},
 
     {"isoformat",   (PyCFunction)date_isoformat,        METH_NOARGS,

From bf168c935b2ce177f46bfc300a74035ba17dae2b Mon Sep 17 00:00:00 2001
From: Dong-hee Na <donghee.na92@gmail.com>
Date: Wed, 11 Sep 2019 00:46:50 +0900
Subject: [PATCH 03/20] bpo-24416: Apply code review

---
 Doc/library/datetime.rst                      |  6 +--
 Lib/datetime.py                               | 25 ++++++++--
 Lib/test/datetimetester.py                    | 49 ++++++++++---------
 .../2019-09-01-15-17-49.bpo-24416.G8Ww1U.rst  |  4 +-
 4 files changed, 54 insertions(+), 30 deletions(-)

diff --git a/Doc/library/datetime.rst b/Doc/library/datetime.rst
index a73c93529ede5d..f977b145d5ad73 100644
--- a/Doc/library/datetime.rst
+++ b/Doc/library/datetime.rst
@@ -670,7 +670,7 @@ Instance methods:
 
 .. method:: date.isocalendar()
 
-   Return a named tuple, (ISO year, ISO week number, ISO weekday).
+   Return a :class:`IsoCalendarDate`, (ISO year, ISO week number, ISO weekday).
 
    The ISO calendar is a widely used variant of the Gregorian calendar. [#]_
 
@@ -689,7 +689,7 @@ Instance methods:
        (2004, 1, 7)
 
    .. versionchanged:: 3.9
-      Result changed from a tuple to a namedtuple.
+      Result changed from a tuple to a :class:`IsoCalendarDate`.
       It can't be unpickled in previous versions.
 
 .. method:: date.isoformat()
@@ -1403,7 +1403,7 @@ Instance methods:
 
 .. method:: datetime.isocalendar()
 
-   Return a named tuple, (ISO year, ISO week number, ISO weekday).
+   Return a :class:`IsoCalendarDate`, (ISO year, ISO week number, ISO weekday).
    The same as ``self.date().isocalendar()``.
 
 
diff --git a/Lib/datetime.py b/Lib/datetime.py
index 571903897c4940..0f227f7211aa64 100644
--- a/Lib/datetime.py
+++ b/Lib/datetime.py
@@ -12,10 +12,29 @@
 import math as _math
 import sys
 
-from collections import namedtuple
 
+class IsoCalendarDate(tuple):
+    def __new__(cls, seq):
+        if len(seq) != 3:
+            raise TypeError(f'{cls.__name__}() takes a 3-sequence '
+                    f'({len(seq)}-sequence given)')
+        return tuple.__new__(cls, seq)
 
-IsoCalendarDate = namedtuple('IsoCalendarDate', 'year week weekday')
+    @property
+    def year(self):
+        return self[0]
+
+    @property
+    def week(self):
+        return self[1]
+
+    @property
+    def weekday(self):
+        return self[2]
+
+    def __repr__(self):
+        return (f'{self.__class__.__name__}'
+            f'(year={self[0]}, week={self[1]}, weekday={self[2]})')
 
 
 def _cmp(x, y):
@@ -1126,7 +1145,7 @@ def isocalendar(self):
             if today >= _isoweek1monday(year+1):
                 year += 1
                 week = 0
-        return IsoCalendarDate(year, week+1, day+1)
+        return IsoCalendarDate((year, week+1, day+1))
 
     # Pickle support.
 
diff --git a/Lib/test/datetimetester.py b/Lib/test/datetimetester.py
index 42dd56206758f3..e05098650f0e9a 100644
--- a/Lib/test/datetimetester.py
+++ b/Lib/test/datetimetester.py
@@ -76,7 +76,7 @@ def test_name_cleanup(self):
         names = set(name for name in dir(datetime)
                     if not name.startswith('__') and not name.endswith('__'))
         allowed = set(['MAXYEAR', 'MINYEAR', 'date', 'datetime',
-                       'datetime_CAPI', 'IsoCalendarDate', 'namedtuple',
+                       'datetime_CAPI', 'IsoCalendarDate',
                        'time', 'timedelta', 'timezone',
                        'tzinfo', 'sys'])
         self.assertEqual(names - allowed, set([]))
@@ -1356,27 +1356,32 @@ def test_weekday(self):
     def test_isocalendar(self):
         # Check examples from
         # http://www.phys.uu.nl/~vgent/calendar/isocalendar.htm
-        for i in range(7):
-            d = self.theclass(2003, 12, 22+i)
-            self.assertEqual(d.isocalendar(), (2003, 52, i+1))
-            d = self.theclass(2003, 12, 29) + timedelta(i)
-            self.assertEqual(d.isocalendar(), (2004, 1, i+1))
-            d = self.theclass(2004, 1, 5+i)
-            self.assertEqual(d.isocalendar(), (2004, 2, i+1))
-            d = self.theclass(2009, 12, 21+i)
-            self.assertEqual(d.isocalendar(), (2009, 52, i+1))
-            d = self.theclass(2009, 12, 28) + timedelta(i)
-            self.assertEqual(d.isocalendar(), (2009, 53, i+1))
-            d = self.theclass(2010, 1, 4+i)
-            self.assertEqual(d.isocalendar(), (2010, 1, i+1))
-
-    def test_isocalendar_named(self):
-        d = self.theclass(2008, 12, 3)
-        t = d.isocalendar()
-        self.assertEqual(t.year, 2008)
-        self.assertEqual(t.week, 49)
-        self.assertEqual(t.weekday, 3)
-        self.assertEqual((2008, 49, 3), t)
+        week_mondays = [
+                ((2003, 12, 22), (2003, 52, 1)),
+                ((2003, 12, 29), (2004, 1, 1)),
+                ((2004, 1, 5), (2004, 2, 1)),
+                ((2009, 12, 21), (2009, 52, 1)),
+                ((2009, 12, 28), (2009, 53, 1)),
+                ((2010, 1, 4), (2010, 1, 1)),
+        ]
+
+        test_cases = []
+        for cal_date, iso_date in week_mondays:
+            base_date = self.theclass(*cal_date)
+            # Adds one test case for every day of the specified weeks
+            for i in range(7):
+                new_date = base_date + timedelta(i)
+                new_iso = iso_date[0:2] + (iso_date[2] + i,)
+                test_cases.append((new_date, new_iso))
+
+        for d, exp_iso in test_cases:
+            with self.subTest(d=d, comparison="tuple"):
+                self.assertEqual(d.isocalendar(), exp_iso)
+
+            # Check that the tuple contents are accessible by field name
+            with self.subTest(d=d, comparison="fields"):
+                t = d.isocalendar()
+                self.assertEqual((t.year, t.week, t.weekday), exp_iso)
 
     def test_iso_long_years(self):
         # Calculate long ISO years and compare to table from
diff --git a/Misc/NEWS.d/next/Library/2019-09-01-15-17-49.bpo-24416.G8Ww1U.rst b/Misc/NEWS.d/next/Library/2019-09-01-15-17-49.bpo-24416.G8Ww1U.rst
index 4a95fb13ac7d43..66ac3992d5f8a9 100644
--- a/Misc/NEWS.d/next/Library/2019-09-01-15-17-49.bpo-24416.G8Ww1U.rst
+++ b/Misc/NEWS.d/next/Library/2019-09-01-15-17-49.bpo-24416.G8Ww1U.rst
@@ -1,3 +1,3 @@
 The ``isocalendar()`` methods of :class:`datetime.date` and
-:class:`datetime.datetime` now return a :term:`named tuple` instead of a
-:class:`tuple`. It can't be unpickled in previous versions.
+:class:`datetime.datetime` now return a :class:`IsoCalendarDate`
+instead of a :class:`tuple`. It can't be unpickled in previous versions.

From f3c02ada6c72122d0a6c69ccbd26e11f068580e0 Mon Sep 17 00:00:00 2001
From: Dong-hee Na <donghee.na92@gmail.com>
Date: Wed, 11 Sep 2019 00:53:28 +0900
Subject: [PATCH 04/20] bpo-24416: Update docstrings

---
 Lib/datetime.py           | 2 +-
 Modules/_datetimemodule.c | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/Lib/datetime.py b/Lib/datetime.py
index 0f227f7211aa64..28fbb76647cde5 100644
--- a/Lib/datetime.py
+++ b/Lib/datetime.py
@@ -1120,7 +1120,7 @@ def isoweekday(self):
         return self.toordinal() % 7 or 7
 
     def isocalendar(self):
-        """Return a named tuple containing ISO year, week number, and weekday.
+        """Return a IsoCalendarDate containing ISO year, week number, and weekday.
 
         The first ISO week of the year is the (Mon-Sun) week
         containing the year's first Thursday; everything else derives
diff --git a/Modules/_datetimemodule.c b/Modules/_datetimemodule.c
index 068043ff89f8ee..3b3427d9e97bb9 100644
--- a/Modules/_datetimemodule.c
+++ b/Modules/_datetimemodule.c
@@ -3420,7 +3420,7 @@ static PyMethodDef date_methods[] = {
      PyDoc_STR("Return time tuple, compatible with time.localtime().")},
 
     {"isocalendar", (PyCFunction)date_isocalendar,  METH_NOARGS,
-     PyDoc_STR("Return a named tuple containing ISO year, week number, and "
+     PyDoc_STR("Return a IsoCalendarDate containing ISO year, week number, and "
                "weekday.")},
 
     {"isoformat",   (PyCFunction)date_isoformat,        METH_NOARGS,

From 9ae18863cdc7760e5a667a0e60352b29e9e75e60 Mon Sep 17 00:00:00 2001
From: Dong-hee Na <donghee.na92@gmail.com>
Date: Wed, 11 Sep 2019 09:30:07 +0900
Subject: [PATCH 05/20] bpo-24416: Apply third's codereview

---
 Doc/library/datetime.rst   |  9 +++---
 Lib/datetime.py            | 58 +++++++++++++++++++++-----------------
 Lib/test/datetimetester.py |  7 ++---
 Modules/_datetimemodule.c  |  5 ++--
 4 files changed, 41 insertions(+), 38 deletions(-)

diff --git a/Doc/library/datetime.rst b/Doc/library/datetime.rst
index f977b145d5ad73..46a12e6c77050c 100644
--- a/Doc/library/datetime.rst
+++ b/Doc/library/datetime.rst
@@ -670,7 +670,8 @@ Instance methods:
 
 .. method:: date.isocalendar()
 
-   Return a :class:`IsoCalendarDate`, (ISO year, ISO week number, ISO weekday).
+   Return a :term:`named tuple` object with three components: `year`, `week`
+   and `weekday`.
 
    The ISO calendar is a widely used variant of the Gregorian calendar. [#]_
 
@@ -689,8 +690,7 @@ Instance methods:
        (2004, 1, 7)
 
    .. versionchanged:: 3.9
-      Result changed from a tuple to a :class:`IsoCalendarDate`.
-      It can't be unpickled in previous versions.
+      Result changed from a tuple to a :term:`named tuple`.
 
 .. method:: date.isoformat()
 
@@ -1403,7 +1403,8 @@ Instance methods:
 
 .. method:: datetime.isocalendar()
 
-   Return a :class:`IsoCalendarDate`, (ISO year, ISO week number, ISO weekday).
+   Return a :term:`named tuple` object with three components: `year`, `week`
+   and `weekday`.
    The same as ``self.date().isocalendar()``.
 
 
diff --git a/Lib/datetime.py b/Lib/datetime.py
index 28fbb76647cde5..9ef5f0fd158243 100644
--- a/Lib/datetime.py
+++ b/Lib/datetime.py
@@ -13,30 +13,6 @@
 import sys
 
 
-class IsoCalendarDate(tuple):
-    def __new__(cls, seq):
-        if len(seq) != 3:
-            raise TypeError(f'{cls.__name__}() takes a 3-sequence '
-                    f'({len(seq)}-sequence given)')
-        return tuple.__new__(cls, seq)
-
-    @property
-    def year(self):
-        return self[0]
-
-    @property
-    def week(self):
-        return self[1]
-
-    @property
-    def weekday(self):
-        return self[2]
-
-    def __repr__(self):
-        return (f'{self.__class__.__name__}'
-            f'(year={self[0]}, week={self[1]}, weekday={self[2]})')
-
-
 def _cmp(x, y):
     return 0 if x == y else 1 if x > y else -1
 
@@ -1145,7 +1121,7 @@ def isocalendar(self):
             if today >= _isoweek1monday(year+1):
                 year += 1
                 week = 0
-        return IsoCalendarDate((year, week+1, day+1))
+        return _IsoCalendarDate((year, week+1, day+1))
 
     # Pickle support.
 
@@ -1235,6 +1211,36 @@ def __reduce__(self):
         else:
             return (self.__class__, args, state)
 
+
+class _IsoCalendarDate(tuple):
+
+    def __new__(cls, seq):
+        if len(seq) != 3:
+            raise TypeError(f'{cls.__name__}() takes a 3-sequence '
+                    f'({len(seq)}-sequence given)')
+        return tuple.__new__(cls, seq)
+
+    @property
+    def year(self):
+        return self[0]
+
+    @property
+    def week(self):
+        return self[1]
+
+    @property
+    def weekday(self):
+        return self[2]
+
+    def __repr__(self):
+        return ('datetime.IsoCalendarDate'
+            f'(year={self[0]}, week={self[1]}, weekday={self[2]})')
+
+
+_IsoCalendarDate.__name__ = "IsoCalendarDate"
+_IsoCalendarDate.__qualname__ = "IsoCalendarDate"
+
+
 _tzinfo_class = tzinfo
 
 class time:
@@ -2540,7 +2546,7 @@ def _name_from_offset(delta):
          _format_time, _format_offset, _is_leap, _isoweek1monday, _math,
          _ord2ymd, _time, _time_class, _tzinfo_class, _wrap_strftime, _ymd2ord,
          _divide_and_round, _parse_isoformat_date, _parse_isoformat_time,
-         _parse_hh_mm_ss_ff)
+         _parse_hh_mm_ss_ff, _IsoCalendarDate)
     # XXX Since import * above excludes names that start with _,
     # docstring does not get overwritten. In the future, it may be
     # appropriate to maintain a single module level docstring and
diff --git a/Lib/test/datetimetester.py b/Lib/test/datetimetester.py
index e05098650f0e9a..9339b6111ae0ad 100644
--- a/Lib/test/datetimetester.py
+++ b/Lib/test/datetimetester.py
@@ -1375,13 +1375,10 @@ def test_isocalendar(self):
                 test_cases.append((new_date, new_iso))
 
         for d, exp_iso in test_cases:
-            with self.subTest(d=d, comparison="tuple"):
-                self.assertEqual(d.isocalendar(), exp_iso)
-
-            # Check that the tuple contents are accessible by field name
-            with self.subTest(d=d, comparison="fields"):
+            with self.subTest(d=d, comparison="fields and tuple"):
                 t = d.isocalendar()
                 self.assertEqual((t.year, t.week, t.weekday), exp_iso)
+                self.assertEqual(d.isocalendar(), exp_iso)
 
     def test_iso_long_years(self):
         # Calculate long ISO years and compare to table from
diff --git a/Modules/_datetimemodule.c b/Modules/_datetimemodule.c
index 3b3427d9e97bb9..1a788fd175c801 100644
--- a/Modules/_datetimemodule.c
+++ b/Modules/_datetimemodule.c
@@ -3420,7 +3420,7 @@ static PyMethodDef date_methods[] = {
      PyDoc_STR("Return time tuple, compatible with time.localtime().")},
 
     {"isocalendar", (PyCFunction)date_isocalendar,  METH_NOARGS,
-     PyDoc_STR("Return a IsoCalendarDate containing ISO year, week number, and "
+     PyDoc_STR("Return a named tuple containing ISO year, week number, and "
                "weekday.")},
 
     {"isoformat",   (PyCFunction)date_isoformat,        METH_NOARGS,
@@ -6561,8 +6561,7 @@ PyInit__datetime(void)
         }
         initialized = 1;
     }
-    Py_INCREF((PyObject *) &StructIsoCalendarDateType);
-    PyModule_AddObject(m, "IsoCalendarDate", (PyObject *) &StructIsoCalendarDateType);
+
 
     Py_INCREF(&PyDateTime_DateType);
     PyModule_AddObject(m, "date", (PyObject *) &PyDateTime_DateType);

From c592159c697167f1200e9fa4ea0a930c21c96a71 Mon Sep 17 00:00:00 2001
From: Dong-hee Na <donghee.na92@gmail.com>
Date: Wed, 11 Sep 2019 13:24:55 +0900
Subject: [PATCH 06/20] bpo-24416: Revert to support pickle

---
 Doc/library/datetime.rst  |  9 ++++-----
 Lib/datetime.py           | 14 +++++---------
 Modules/_datetimemodule.c |  3 ++-
 3 files changed, 11 insertions(+), 15 deletions(-)

diff --git a/Doc/library/datetime.rst b/Doc/library/datetime.rst
index 46a12e6c77050c..0f2951a3ee037d 100644
--- a/Doc/library/datetime.rst
+++ b/Doc/library/datetime.rst
@@ -670,8 +670,8 @@ Instance methods:
 
 .. method:: date.isocalendar()
 
-   Return a :term:`named tuple` object with three components: `year`, `week`
-   and `weekday`.
+   Return a :term:`named tuple` object with three components: ``year``,
+   ``week`` and ``weekday``.
 
    The ISO calendar is a widely used variant of the Gregorian calendar. [#]_
 
@@ -1403,9 +1403,8 @@ Instance methods:
 
 .. method:: datetime.isocalendar()
 
-   Return a :term:`named tuple` object with three components: `year`, `week`
-   and `weekday`.
-   The same as ``self.date().isocalendar()``.
+   Return a :term:`named tuple` with three components: ``year``, ``week``
+   and ``weekday``. The same as ``self.date().isocalendar()``.
 
 
 .. method:: datetime.isoformat(sep='T', timespec='auto')
diff --git a/Lib/datetime.py b/Lib/datetime.py
index 9ef5f0fd158243..fa3c46bdd65890 100644
--- a/Lib/datetime.py
+++ b/Lib/datetime.py
@@ -1096,7 +1096,7 @@ def isoweekday(self):
         return self.toordinal() % 7 or 7
 
     def isocalendar(self):
-        """Return a IsoCalendarDate containing ISO year, week number, and weekday.
+        """Return a named tuple containing ISO year, week number, and weekday.
 
         The first ISO week of the year is the (Mon-Sun) week
         containing the year's first Thursday; everything else derives
@@ -1121,7 +1121,7 @@ def isocalendar(self):
             if today >= _isoweek1monday(year+1):
                 year += 1
                 week = 0
-        return _IsoCalendarDate((year, week+1, day+1))
+        return IsoCalendarDate((year, week+1, day+1))
 
     # Pickle support.
 
@@ -1212,7 +1212,7 @@ def __reduce__(self):
             return (self.__class__, args, state)
 
 
-class _IsoCalendarDate(tuple):
+class IsoCalendarDate(tuple):
 
     def __new__(cls, seq):
         if len(seq) != 3:
@@ -1233,14 +1233,10 @@ def weekday(self):
         return self[2]
 
     def __repr__(self):
-        return ('datetime.IsoCalendarDate'
+        return (f'{self.__class__.__name__}'
             f'(year={self[0]}, week={self[1]}, weekday={self[2]})')
 
 
-_IsoCalendarDate.__name__ = "IsoCalendarDate"
-_IsoCalendarDate.__qualname__ = "IsoCalendarDate"
-
-
 _tzinfo_class = tzinfo
 
 class time:
@@ -2546,7 +2542,7 @@ def _name_from_offset(delta):
          _format_time, _format_offset, _is_leap, _isoweek1monday, _math,
          _ord2ymd, _time, _time_class, _tzinfo_class, _wrap_strftime, _ymd2ord,
          _divide_and_round, _parse_isoformat_date, _parse_isoformat_time,
-         _parse_hh_mm_ss_ff, _IsoCalendarDate)
+         _parse_hh_mm_ss_ff)
     # XXX Since import * above excludes names that start with _,
     # docstring does not get overwritten. In the future, it may be
     # appropriate to maintain a single module level docstring and
diff --git a/Modules/_datetimemodule.c b/Modules/_datetimemodule.c
index 1a788fd175c801..068043ff89f8ee 100644
--- a/Modules/_datetimemodule.c
+++ b/Modules/_datetimemodule.c
@@ -6561,7 +6561,8 @@ PyInit__datetime(void)
         }
         initialized = 1;
     }
-
+    Py_INCREF((PyObject *) &StructIsoCalendarDateType);
+    PyModule_AddObject(m, "IsoCalendarDate", (PyObject *) &StructIsoCalendarDateType);
 
     Py_INCREF(&PyDateTime_DateType);
     PyModule_AddObject(m, "date", (PyObject *) &PyDateTime_DateType);

From 87ad62c7aa234780863640750fa6a92dc658c1d1 Mon Sep 17 00:00:00 2001
From: Dong-hee Na <donghee.na92@gmail.com>
Date: Wed, 11 Sep 2019 13:26:50 +0900
Subject: [PATCH 07/20] bpo-24416: Update misc/news

---
 .../next/Library/2019-09-01-15-17-49.bpo-24416.G8Ww1U.rst     | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Misc/NEWS.d/next/Library/2019-09-01-15-17-49.bpo-24416.G8Ww1U.rst b/Misc/NEWS.d/next/Library/2019-09-01-15-17-49.bpo-24416.G8Ww1U.rst
index 66ac3992d5f8a9..ee9af990f079db 100644
--- a/Misc/NEWS.d/next/Library/2019-09-01-15-17-49.bpo-24416.G8Ww1U.rst
+++ b/Misc/NEWS.d/next/Library/2019-09-01-15-17-49.bpo-24416.G8Ww1U.rst
@@ -1,3 +1,3 @@
 The ``isocalendar()`` methods of :class:`datetime.date` and
-:class:`datetime.datetime` now return a :class:`IsoCalendarDate`
-instead of a :class:`tuple`. It can't be unpickled in previous versions.
+:class:`datetime.datetime` now return a :term:`named tuple`
+instead of a :class:`tuple`.

From 63d1ed9a4d48cd32408e1044ab6b952a6ad93d09 Mon Sep 17 00:00:00 2001
From: Dong-hee Na <donghee.na92@gmail.com>
Date: Wed, 11 Sep 2019 15:56:41 +0900
Subject: [PATCH 08/20] bpo-24416: Update __new__

---
 Lib/datetime.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Lib/datetime.py b/Lib/datetime.py
index fa3c46bdd65890..eae63c4a668c92 100644
--- a/Lib/datetime.py
+++ b/Lib/datetime.py
@@ -1218,7 +1218,7 @@ def __new__(cls, seq):
         if len(seq) != 3:
             raise TypeError(f'{cls.__name__}() takes a 3-sequence '
                     f'({len(seq)}-sequence given)')
-        return tuple.__new__(cls, seq)
+        return super().__new__(cls, seq)
 
     @property
     def year(self):

From 752aad8d77db1ad5c7464b50b19f6ceb090f9e2a Mon Sep 17 00:00:00 2001
From: Paul Ganssle <paul@ganssle.io>
Date: Wed, 11 Sep 2019 12:43:04 +0100
Subject: [PATCH 09/20] Change pickling behavior of isocalendar() objects

In order to leave IsocalendarDate as a private class and to improve what
backwards compatibility is offered for pickling the result of a
datetime.isocalendar() call, add a __reduce__ method to the named tuples
that reduces them to plain tuples.

Also add a test to this effect.
---
 Lib/datetime.py            |  5 +++-
 Lib/test/datetimetester.py | 15 +++++++++++
 Modules/_datetimemodule.c  | 55 ++++++++++++++++++++++++++++++++------
 3 files changed, 66 insertions(+), 9 deletions(-)

diff --git a/Lib/datetime.py b/Lib/datetime.py
index eae63c4a668c92..19f0754b7feb36 100644
--- a/Lib/datetime.py
+++ b/Lib/datetime.py
@@ -1232,9 +1232,12 @@ def week(self):
     def weekday(self):
         return self[2]
 
+    def __reduce__(self):
+        return (tuple, (tuple(self),))
+
     def __repr__(self):
         return (f'{self.__class__.__name__}'
-            f'(year={self[0]}, week={self[1]}, weekday={self[2]})')
+                f'(year={self[0]}, week={self[1]}, weekday={self[2]})')
 
 
 _tzinfo_class = tzinfo
diff --git a/Lib/test/datetimetester.py b/Lib/test/datetimetester.py
index 9339b6111ae0ad..4ef93df7aa355d 100644
--- a/Lib/test/datetimetester.py
+++ b/Lib/test/datetimetester.py
@@ -2,6 +2,7 @@
 
 See http://www.zope.org/Members/fdrake/DateTimeWiki/TestCases
 """
+import io
 import itertools
 import bisect
 import copy
@@ -1380,6 +1381,20 @@ def test_isocalendar(self):
                 self.assertEqual((t.year, t.week, t.weekday), exp_iso)
                 self.assertEqual(d.isocalendar(), exp_iso)
 
+    def test_isocalendar_pickling(self):
+        """Test that the result of datetime.isocalendar() can be pickled.
+
+        The result of a round trip should be a plain tuple.
+        """
+        d = self.theclass(2019, 1, 1)
+        f = io.BytesIO()
+        pickle.dump(d.isocalendar(), f)
+        f.seek(0)
+
+        res = pickle.load(f)
+
+        self.assertEqual(res, (2019, 1, 2))
+
     def test_iso_long_years(self):
         # Calculate long ISO years and compare to table from
         # http://www.phys.uu.nl/~vgent/calendar/isocalendar.htm
diff --git a/Modules/_datetimemodule.c b/Modules/_datetimemodule.c
index 068043ff89f8ee..27971317e2dadb 100644
--- a/Modules/_datetimemodule.c
+++ b/Modules/_datetimemodule.c
@@ -3245,9 +3245,53 @@ static PyStructSequence_Desc struct_iso_calendar_date_desc = {
     3
 };
 
-static int initialized;
+static int isocalendardate_initialized;
 static PyTypeObject StructIsoCalendarDateType;
 
+// Required for pickling as a tuple
+static PyObject *
+isocalendardate_reduce(PyObject *self, PyObject *Py_UNUSED(ignored))
+{
+    // Construct the tuple that this reduces to
+    PyObject * reduce_tuple = Py_BuildValue(
+        "O((OOO))", &PyTuple_Type,
+        PyStructSequence_GET_ITEM(self, 0),
+        PyStructSequence_GET_ITEM(self, 1),
+        PyStructSequence_GET_ITEM(self, 2)
+    );
+
+    return reduce_tuple;
+}
+
+/* Method to add our custom reduce type to the IsoCalendarDate type */
+static int
+_initialize_isocalendardate() {
+    if (isocalendardate_initialized) {
+        return 0;
+    }
+
+    if (PyStructSequence_InitType2(&StructIsoCalendarDateType,
+                                   &struct_iso_calendar_date_desc) < 0) {
+        return -1;
+    }
+
+    // Add our custom __reduce__
+    PyMethodDef *method = StructIsoCalendarDateType.tp_methods;
+    int reduce_missing = 1;
+    while (method != NULL) {
+        if (strcmp("__reduce__", method->ml_name) == 0) {
+            reduce_missing = 0;
+            method->ml_meth = (PyCFunction)isocalendardate_reduce;
+            method->ml_doc = "Reduce IsoCalendarDate to a simple tuple";
+
+            break;
+        }
+    }
+
+    assert(!reduce_missing);
+    return 0;
+}
+
 static PyObject *
 date_isocalendar(PyDateTime_Date *self, PyObject *Py_UNUSED(ignored))
 {
@@ -6554,15 +6598,10 @@ PyInit__datetime(void)
     PyModule_AddIntMacro(m, MAXYEAR);
 
     /* IsoCalendarDate */
-    if (!initialized) {
-        if (PyStructSequence_InitType2(&StructIsoCalendarDateType,
-                                       &struct_iso_calendar_date_desc) < 0) {
-            return NULL;
-        }
-        initialized = 1;
+    if (_initialize_isocalendardate()) {
+        return NULL;
     }
     Py_INCREF((PyObject *) &StructIsoCalendarDateType);
-    PyModule_AddObject(m, "IsoCalendarDate", (PyObject *) &StructIsoCalendarDateType);
 
     Py_INCREF(&PyDateTime_DateType);
     PyModule_AddObject(m, "date", (PyObject *) &PyDateTime_DateType);

From 4b2dc8b373f9acebcd020db86e468feeb92b0faa Mon Sep 17 00:00:00 2001
From: Paul Ganssle <paul@ganssle.io>
Date: Wed, 11 Sep 2019 12:47:15 +0100
Subject: [PATCH 10/20] Rename IsoCalendarDate to _IsoCalendarDate

---
 Lib/datetime.py | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/Lib/datetime.py b/Lib/datetime.py
index 19f0754b7feb36..b806ee099a7e32 100644
--- a/Lib/datetime.py
+++ b/Lib/datetime.py
@@ -1121,7 +1121,7 @@ def isocalendar(self):
             if today >= _isoweek1monday(year+1):
                 year += 1
                 week = 0
-        return IsoCalendarDate((year, week+1, day+1))
+        return _IsoCalendarDate((year, week+1, day+1))
 
     # Pickle support.
 
@@ -1239,6 +1239,9 @@ def __repr__(self):
         return (f'{self.__class__.__name__}'
                 f'(year={self[0]}, week={self[1]}, weekday={self[2]})')
 
+_IsoCalendarDate = IsoCalendarDate
+del IsoCalendarDate
+
 
 _tzinfo_class = tzinfo
 
@@ -2545,7 +2548,7 @@ def _name_from_offset(delta):
          _format_time, _format_offset, _is_leap, _isoweek1monday, _math,
          _ord2ymd, _time, _time_class, _tzinfo_class, _wrap_strftime, _ymd2ord,
          _divide_and_round, _parse_isoformat_date, _parse_isoformat_time,
-         _parse_hh_mm_ss_ff)
+         _parse_hh_mm_ss_ff, _IsoCalendarDate)
     # XXX Since import * above excludes names that start with _,
     # docstring does not get overwritten. In the future, it may be
     # appropriate to maintain a single module level docstring and

From 205b6c54aeef1532d8dbfc14d869b264fb63c7cb Mon Sep 17 00:00:00 2001
From: Dong-hee Na <donghee.na92@gmail.com>
Date: Wed, 11 Sep 2019 21:52:58 +0900
Subject: [PATCH 11/20] bpo-24416: Update datetime.rst

---
 Doc/library/datetime.rst | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/Doc/library/datetime.rst b/Doc/library/datetime.rst
index 0f2951a3ee037d..ea0d3c0d2d9592 100644
--- a/Doc/library/datetime.rst
+++ b/Doc/library/datetime.rst
@@ -683,11 +683,11 @@ Instance methods:
    For example, 2004 begins on a Thursday, so the first week of ISO year 2004
    begins on Monday, 29 Dec 2003 and ends on Sunday, 4 Jan 2004::
 
-       >>> from datetime import date
-       >>> date(2003, 12, 29).isocalendar()
-       (2004, 1, 1)
-       >>> date(2004, 1, 4).isocalendar()
-       (2004, 1, 7)
+        >>> from datetime import date
+        >>> date(2003, 12, 29).isocalendar()
+        datetime.IsoCalendarDate(year=2004, week=1, weekday=1)
+        >>> date(2004, 1, 4).isocalendar()
+        datetime.IsoCalendarDate(year=2004, week=1, weekday=7)
 
    .. versionchanged:: 3.9
       Result changed from a tuple to a :term:`named tuple`.

From 32cc8c183873bb01a3dfc7f35f394be2de403077 Mon Sep 17 00:00:00 2001
From: Dong-hee Na <donghee.na92@gmail.com>
Date: Wed, 11 Sep 2019 21:57:37 +0900
Subject: [PATCH 12/20] bpo-24416: Update unittest

---
 Lib/datetime.py            | 1 -
 Lib/test/datetimetester.py | 7 +++++--
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/Lib/datetime.py b/Lib/datetime.py
index b806ee099a7e32..0fefb4262d2838 100644
--- a/Lib/datetime.py
+++ b/Lib/datetime.py
@@ -12,7 +12,6 @@
 import math as _math
 import sys
 
-
 def _cmp(x, y):
     return 0 if x == y else 1 if x > y else -1
 
diff --git a/Lib/test/datetimetester.py b/Lib/test/datetimetester.py
index 4ef93df7aa355d..ccbb31c239bcfb 100644
--- a/Lib/test/datetimetester.py
+++ b/Lib/test/datetimetester.py
@@ -1376,10 +1376,13 @@ def test_isocalendar(self):
                 test_cases.append((new_date, new_iso))
 
         for d, exp_iso in test_cases:
-            with self.subTest(d=d, comparison="fields and tuple"):
+            with self.subTest(d=d, comparison="tuple"):
+                self.assertEqual(d.isocalendar(), exp_iso)
+
+            # Check that the tuple contents are accessible by field name
+            with self.subTest(d=d, comparison="fields"):
                 t = d.isocalendar()
                 self.assertEqual((t.year, t.week, t.weekday), exp_iso)
-                self.assertEqual(d.isocalendar(), exp_iso)
 
     def test_isocalendar_pickling(self):
         """Test that the result of datetime.isocalendar() can be pickled.

From 41057ff40714cc0d8d30f83dab8531e481a25de6 Mon Sep 17 00:00:00 2001
From: Paul Ganssle <paul@ganssle.io>
Date: Wed, 11 Sep 2019 15:03:55 +0100
Subject: [PATCH 13/20] Revert "Rename IsoCalendarDate to _IsoCalendarDate"

This reverts commit 448a2109dfde1558a082de78171d17580995a950.
---
 Lib/datetime.py | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/Lib/datetime.py b/Lib/datetime.py
index 0fefb4262d2838..fb44f211a77487 100644
--- a/Lib/datetime.py
+++ b/Lib/datetime.py
@@ -1120,7 +1120,7 @@ def isocalendar(self):
             if today >= _isoweek1monday(year+1):
                 year += 1
                 week = 0
-        return _IsoCalendarDate((year, week+1, day+1))
+        return IsoCalendarDate((year, week+1, day+1))
 
     # Pickle support.
 
@@ -1238,9 +1238,6 @@ def __repr__(self):
         return (f'{self.__class__.__name__}'
                 f'(year={self[0]}, week={self[1]}, weekday={self[2]})')
 
-_IsoCalendarDate = IsoCalendarDate
-del IsoCalendarDate
-
 
 _tzinfo_class = tzinfo
 
@@ -2547,7 +2544,7 @@ def _name_from_offset(delta):
          _format_time, _format_offset, _is_leap, _isoweek1monday, _math,
          _ord2ymd, _time, _time_class, _tzinfo_class, _wrap_strftime, _ymd2ord,
          _divide_and_round, _parse_isoformat_date, _parse_isoformat_time,
-         _parse_hh_mm_ss_ff, _IsoCalendarDate)
+         _parse_hh_mm_ss_ff)
     # XXX Since import * above excludes names that start with _,
     # docstring does not get overwritten. In the future, it may be
     # appropriate to maintain a single module level docstring and

From 9c98a61ad2d127c1883ef9cabca6c77c72f76649 Mon Sep 17 00:00:00 2001
From: Paul Ganssle <paul@ganssle.io>
Date: Wed, 11 Sep 2019 15:03:57 +0100
Subject: [PATCH 14/20] Revert "Change pickling behavior of isocalendar()
 objects"

This reverts commit 104264121ea49795da87fc803a270bdda8fa21d2.
---
 Lib/datetime.py            |  5 +---
 Lib/test/datetimetester.py | 15 -----------
 Modules/_datetimemodule.c  | 55 ++++++--------------------------------
 3 files changed, 9 insertions(+), 66 deletions(-)

diff --git a/Lib/datetime.py b/Lib/datetime.py
index fb44f211a77487..dc55013d1cf860 100644
--- a/Lib/datetime.py
+++ b/Lib/datetime.py
@@ -1231,12 +1231,9 @@ def week(self):
     def weekday(self):
         return self[2]
 
-    def __reduce__(self):
-        return (tuple, (tuple(self),))
-
     def __repr__(self):
         return (f'{self.__class__.__name__}'
-                f'(year={self[0]}, week={self[1]}, weekday={self[2]})')
+            f'(year={self[0]}, week={self[1]}, weekday={self[2]})')
 
 
 _tzinfo_class = tzinfo
diff --git a/Lib/test/datetimetester.py b/Lib/test/datetimetester.py
index ccbb31c239bcfb..e05098650f0e9a 100644
--- a/Lib/test/datetimetester.py
+++ b/Lib/test/datetimetester.py
@@ -2,7 +2,6 @@
 
 See http://www.zope.org/Members/fdrake/DateTimeWiki/TestCases
 """
-import io
 import itertools
 import bisect
 import copy
@@ -1384,20 +1383,6 @@ def test_isocalendar(self):
                 t = d.isocalendar()
                 self.assertEqual((t.year, t.week, t.weekday), exp_iso)
 
-    def test_isocalendar_pickling(self):
-        """Test that the result of datetime.isocalendar() can be pickled.
-
-        The result of a round trip should be a plain tuple.
-        """
-        d = self.theclass(2019, 1, 1)
-        f = io.BytesIO()
-        pickle.dump(d.isocalendar(), f)
-        f.seek(0)
-
-        res = pickle.load(f)
-
-        self.assertEqual(res, (2019, 1, 2))
-
     def test_iso_long_years(self):
         # Calculate long ISO years and compare to table from
         # http://www.phys.uu.nl/~vgent/calendar/isocalendar.htm
diff --git a/Modules/_datetimemodule.c b/Modules/_datetimemodule.c
index 27971317e2dadb..068043ff89f8ee 100644
--- a/Modules/_datetimemodule.c
+++ b/Modules/_datetimemodule.c
@@ -3245,53 +3245,9 @@ static PyStructSequence_Desc struct_iso_calendar_date_desc = {
     3
 };
 
-static int isocalendardate_initialized;
+static int initialized;
 static PyTypeObject StructIsoCalendarDateType;
 
-// Required for pickling as a tuple
-static PyObject *
-isocalendardate_reduce(PyObject *self, PyObject *Py_UNUSED(ignored))
-{
-    // Construct the tuple that this reduces to
-    PyObject * reduce_tuple = Py_BuildValue(
-        "O((OOO))", &PyTuple_Type,
-        PyStructSequence_GET_ITEM(self, 0),
-        PyStructSequence_GET_ITEM(self, 1),
-        PyStructSequence_GET_ITEM(self, 2)
-    );
-
-    return reduce_tuple;
-}
-
-/* Method to add our custom reduce type to the IsoCalendarDate type */
-static int
-_initialize_isocalendardate() {
-    if (isocalendardate_initialized) {
-        return 0;
-    }
-
-    if (PyStructSequence_InitType2(&StructIsoCalendarDateType,
-                                   &struct_iso_calendar_date_desc) < 0) {
-        return -1;
-    }
-
-    // Add our custom __reduce__
-    PyMethodDef *method = StructIsoCalendarDateType.tp_methods;
-    int reduce_missing = 1;
-    while (method != NULL) {
-        if (strcmp("__reduce__", method->ml_name) == 0) {
-            reduce_missing = 0;
-            method->ml_meth = (PyCFunction)isocalendardate_reduce;
-            method->ml_doc = "Reduce IsoCalendarDate to a simple tuple";
-
-            break;
-        }
-    }
-
-    assert(!reduce_missing);
-    return 0;
-}
-
 static PyObject *
 date_isocalendar(PyDateTime_Date *self, PyObject *Py_UNUSED(ignored))
 {
@@ -6598,10 +6554,15 @@ PyInit__datetime(void)
     PyModule_AddIntMacro(m, MAXYEAR);
 
     /* IsoCalendarDate */
-    if (_initialize_isocalendardate()) {
-        return NULL;
+    if (!initialized) {
+        if (PyStructSequence_InitType2(&StructIsoCalendarDateType,
+                                       &struct_iso_calendar_date_desc) < 0) {
+            return NULL;
+        }
+        initialized = 1;
     }
     Py_INCREF((PyObject *) &StructIsoCalendarDateType);
+    PyModule_AddObject(m, "IsoCalendarDate", (PyObject *) &StructIsoCalendarDateType);
 
     Py_INCREF(&PyDateTime_DateType);
     PyModule_AddObject(m, "date", (PyObject *) &PyDateTime_DateType);

From d4ce1e77c73bdf56b4f957b3e11641897bc6e9b0 Mon Sep 17 00:00:00 2001
From: Dong-hee Na <donghee.na92@gmail.com>
Date: Thu, 12 Sep 2019 02:45:27 +0900
Subject: [PATCH 15/20] bpo-24416: Add pickle test

---
 Lib/test/datetimetester.py | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/Lib/test/datetimetester.py b/Lib/test/datetimetester.py
index e05098650f0e9a..990ff504bade72 100644
--- a/Lib/test/datetimetester.py
+++ b/Lib/test/datetimetester.py
@@ -2,6 +2,7 @@
 
 See http://www.zope.org/Members/fdrake/DateTimeWiki/TestCases
 """
+import io
 import itertools
 import bisect
 import copy
@@ -1383,6 +1384,19 @@ def test_isocalendar(self):
                 t = d.isocalendar()
                 self.assertEqual((t.year, t.week, t.weekday), exp_iso)
 
+    def test_isocalendar_pickling(self):
+        """Test that the result of datetime.isocalendar() can be pickled.
+
+        The result of a round trip should be a plain tuple.
+        """
+        d = self.theclass(2019, 1, 1)
+        f = io.BytesIO()
+        pickle.dump(d.isocalendar(), f)
+        f.seek(0)
+        res = pickle.load(f)
+
+        self.assertEqual(res, (2019, 1, 2))
+
     def test_iso_long_years(self):
         # Calculate long ISO years and compare to table from
         # http://www.phys.uu.nl/~vgent/calendar/isocalendar.htm

From 2987fdc791e9df44c133a9ee76d6c1553a8a6eb1 Mon Sep 17 00:00:00 2001
From: Dong-hee Na <donghee.na92@gmail.com>
Date: Sat, 21 Sep 2019 22:14:52 +0900
Subject: [PATCH 16/20] bpo-24416: Update C API to subclass tuple

---
 Modules/_datetimemodule.c          | 189 +++++++++++++++++++++++------
 Modules/clinic/_datetimemodule.c.h |  27 ++++-
 2 files changed, 180 insertions(+), 36 deletions(-)

diff --git a/Modules/_datetimemodule.c b/Modules/_datetimemodule.c
index 068043ff89f8ee..64c2c8b7b11821 100644
--- a/Modules/_datetimemodule.c
+++ b/Modules/_datetimemodule.c
@@ -38,8 +38,9 @@
 module datetime
 class datetime.datetime "PyDateTime_DateTime *" "&PyDateTime_DateTimeType"
 class datetime.date "PyDateTime_Date *" "&PyDateTime_DateType"
+class datetime.IsoCalendarDate "PyDateTime_IsoCalendarDate *" "&PyDateTime_IsoCalendarDateType"
 [clinic start generated code]*/
-/*[clinic end generated code: output=da39a3ee5e6b4b0d input=25138ad6a696b785]*/
+/*[clinic end generated code: output=da39a3ee5e6b4b0d input=81bec0fa19837f63]*/
 
 #include "clinic/_datetimemodule.c.h"
 
@@ -131,6 +132,7 @@ class datetime.date "PyDateTime_Date *" "&PyDateTime_DateType"
 static PyTypeObject PyDateTime_DateType;
 static PyTypeObject PyDateTime_DateTimeType;
 static PyTypeObject PyDateTime_DeltaType;
+static PyTypeObject PyDateTime_IsoCalendarDateType;
 static PyTypeObject PyDateTime_TimeType;
 static PyTypeObject PyDateTime_TZInfoType;
 static PyTypeObject PyDateTime_TimeZoneType;
@@ -3225,28 +3227,153 @@ date_isoweekday(PyDateTime_Date *self, PyObject *Py_UNUSED(ignored))
     return PyLong_FromLong(dow + 1);
 }
 
-static PyStructSequence_Field struct_iso_calendar_date_fields[] = {
-    {"year", "year, for example, 1993"},
-    {"week", "week, range [1, 53]"},
-    {"weekday", "week day, range [1, 7]"},
-    {0}
-};
-
-PyDoc_STRVAR(struct_iso_calendar_date__doc__,
+PyDoc_STRVAR(iso_calendar_date__doc__,
 "The result of date.isocalendar() or datetime.isocalendar()\n\n\
 This object may be accessed either as a tuple of\n\
   ((year, week, weekday)\n\
 or via the object attributes as named in the above tuple.");
 
-static PyStructSequence_Desc struct_iso_calendar_date_desc = {
-    "datetime.IsoCalendarDate",
-    struct_iso_calendar_date__doc__,
-    struct_iso_calendar_date_fields,
-    3
+typedef struct {
+    PyTupleObject tuple;
+} PyDateTime_IsoCalendarDate;
+
+static PyObject *
+iso_calendar_date_repr(PyDateTime_IsoCalendarDate *self)
+{
+    PyObject* year = PyTuple_GetItem((PyObject *)self, 0);
+    if (year == NULL) {
+        return NULL;
+    }
+    PyObject* week = PyTuple_GetItem((PyObject *)self, 1);
+    if (week == NULL) {
+        return NULL;
+    }
+    PyObject* weekday = PyTuple_GetItem((PyObject *)self, 2);
+    if (weekday == NULL) {
+        return NULL;
+    }
+
+    return PyUnicode_FromFormat("%.200s(year=%S, week=%S, weekday=%S)",
+                               Py_TYPE(self)->tp_name, year, week, weekday);
+}
+
+static PyObject *
+iso_calendar_date_year(PyDateTime_IsoCalendarDate *self, void *unused)
+{
+    PyObject* year =  PyTuple_GetItem((PyObject *)self, 0);
+    if(year == NULL) {
+        return NULL;
+    }
+    Py_INCREF(year);
+    return year;
+}
+
+static PyObject *
+iso_calendar_date_week(PyDateTime_IsoCalendarDate *self, void *unused)
+{
+    PyObject* week =  PyTuple_GetItem((PyObject *)self, 1);
+    if (week == NULL) {
+        return NULL;
+    }
+    Py_INCREF(week);
+    return week;
+}
+
+static PyObject *
+iso_calendar_date_weekday(PyDateTime_IsoCalendarDate *self, void *unused)
+{
+    PyObject* weekday =  PyTuple_GetItem((PyObject *)self, 2);
+    if(weekday == NULL) {
+        return NULL;
+    }
+    Py_INCREF(weekday);
+    return weekday;
+}
+
+static PyGetSetDef iso_calendar_date_getset[] = {
+    {"year",        (getter)iso_calendar_date_year},
+    {"week",      (getter)iso_calendar_date_week},
+    {"weekday",      (getter)iso_calendar_date_weekday},
+    {NULL}
 };
 
-static int initialized;
-static PyTypeObject StructIsoCalendarDateType;
+static PyTypeObject PyDateTime_IsoCalendarDateType = {
+    PyVarObject_HEAD_INIT(NULL, 0)
+    "datetime.IsoCalendarDate",                         /* tp_name */
+    sizeof(PyDateTime_IsoCalendarDate),                 /* tp_basicsize */
+    0,                                                  /* tp_itemsize */
+    0,                                                  /* tp_dealloc */
+    0,                                                  /* tp_vectorcall_offset */
+    0,                                                  /* tp_getattr */
+    0,                                                  /* tp_setattr */
+    0,                                                  /* tp_as_async */
+    (reprfunc) iso_calendar_date_repr,                  /* tp_repr */
+    0,                                                  /* tp_as_number */
+    0,                                                  /* tp_as_sequence */
+    0,                                                  /* tp_as_mapping */
+    0,                                                  /* tp_hash */
+    0,                                                  /* tp_call */
+    0,                                                  /* tp_str */
+    0,                                                  /* tp_getattro */
+    0,                                                  /* tp_setattro */
+    0,                                                  /* tp_as_buffer */
+    Py_TPFLAGS_DEFAULT,                                 /* tp_flags */
+    iso_calendar_date__doc__,                           /* tp_doc */
+    0,                                                  /* tp_traverse */
+    0,                                                  /* tp_clear */
+    0,                                                  /* tp_richcompare */
+    0,                                                  /* tp_weaklistoffset */
+    0,                                                  /* tp_iter */
+    0,                                                  /* tp_iternext */
+    0,                                                  /* tp_methods */
+    0,                                                  /* tp_members */
+    iso_calendar_date_getset,                           /* tp_getset */
+    &PyTuple_Type,                                      /* tp_base */
+    0,                                                  /* tp_dict */
+    0,                                                  /* tp_descr_get */
+    0,                                                  /* tp_descr_set */
+    0,                                                  /* tp_dictoffset */
+    0,                                                  /* tp_init */
+    0,                                                  /* tp_alloc */
+    iso_calendar_date_new,                              /* tp_new */
+};
+
+/*[clinic input]
+@classmethod
+datetime.IsoCalendarDate.__new__ as iso_calendar_date_new
+    sequence as seq: object
+[clinic start generated code]*/
+
+static PyObject *
+iso_calendar_date_new_impl(PyTypeObject *type, PyObject *seq)
+/*[clinic end generated code: output=bf2e1982e7012dae input=f9bb6626d4947edc]*/
+{
+    PyDateTime_IsoCalendarDate* self;
+    Py_ssize_t len = PyObject_Length(seq);
+    if (len == -1) {
+        return NULL;
+    }
+
+    if (len != 3) {
+        PyErr_Format(PyExc_TypeError,
+                     "%.500s() takes a 3-sequence (%zd-sequence given)",
+                     type->tp_name, len);
+        return NULL;
+    }
+
+    self = (PyDateTime_IsoCalendarDate *) type->tp_alloc(type, len);
+    if (self == NULL) {
+        return NULL;
+    }
+
+    for (int i = 0; i < len; ++i) {
+        PyObject* v = PyTuple_GetItem(seq, i);
+        Py_INCREF(v);
+        PyTuple_SET_ITEM(self, i, v);
+    }
+
+    return (PyObject *)self;
+}
 
 static PyObject *
 date_isocalendar(PyDateTime_Date *self, PyObject *Py_UNUSED(ignored))
@@ -3268,19 +3395,17 @@ date_isocalendar(PyDateTime_Date *self, PyObject *Py_UNUSED(ignored))
         week = 0;
     }
 
-    PyObject *v = PyStructSequence_New(&StructIsoCalendarDateType);
-    if (v == NULL) {
+    PyObject *seq = Py_BuildValue("iii", year, week + 1, day + 1);
+    if (seq == NULL) {
         return NULL;
     }
 
-    PyStructSequence_SET_ITEM(v, 0, PyLong_FromLong(year));
-    PyStructSequence_SET_ITEM(v, 1, PyLong_FromLong(week + 1));
-    PyStructSequence_SET_ITEM(v, 2, PyLong_FromLong(day + 1));
-
-    if (PyErr_Occurred()) {
-        Py_DECREF(v);
+    PyObject* v = iso_calendar_date_new_impl(&PyDateTime_IsoCalendarDateType, seq);
+    if(v == NULL) {
+        Py_DECREF(seq);
         return NULL;
     }
+    Py_DECREF(seq);
     return v;
 }
 
@@ -6430,6 +6555,8 @@ PyInit__datetime(void)
         return NULL;
     if (PyType_Ready(&PyDateTime_DeltaType) < 0)
         return NULL;
+    if (PyType_Ready(&PyDateTime_IsoCalendarDateType) < 0)
+        return NULL;
     if (PyType_Ready(&PyDateTime_TimeType) < 0)
         return NULL;
     if (PyType_Ready(&PyDateTime_TZInfoType) < 0)
@@ -6553,17 +6680,6 @@ PyInit__datetime(void)
     PyModule_AddIntMacro(m, MINYEAR);
     PyModule_AddIntMacro(m, MAXYEAR);
 
-    /* IsoCalendarDate */
-    if (!initialized) {
-        if (PyStructSequence_InitType2(&StructIsoCalendarDateType,
-                                       &struct_iso_calendar_date_desc) < 0) {
-            return NULL;
-        }
-        initialized = 1;
-    }
-    Py_INCREF((PyObject *) &StructIsoCalendarDateType);
-    PyModule_AddObject(m, "IsoCalendarDate", (PyObject *) &StructIsoCalendarDateType);
-
     Py_INCREF(&PyDateTime_DateType);
     PyModule_AddObject(m, "date", (PyObject *) &PyDateTime_DateType);
 
@@ -6571,6 +6687,9 @@ PyInit__datetime(void)
     PyModule_AddObject(m, "datetime",
                        (PyObject *)&PyDateTime_DateTimeType);
 
+    Py_INCREF((PyObject *) &PyDateTime_IsoCalendarDateType);
+    PyModule_AddObject(m, "IsoCalendarDate", (PyObject *) &PyDateTime_IsoCalendarDateType);
+
     Py_INCREF(&PyDateTime_TimeType);
     PyModule_AddObject(m, "time", (PyObject *) &PyDateTime_TimeType);
 
diff --git a/Modules/clinic/_datetimemodule.c.h b/Modules/clinic/_datetimemodule.c.h
index 447036ca03814c..6f121ad72d5b88 100644
--- a/Modules/clinic/_datetimemodule.c.h
+++ b/Modules/clinic/_datetimemodule.c.h
@@ -14,6 +14,31 @@ PyDoc_STRVAR(datetime_date_fromtimestamp__doc__,
 #define DATETIME_DATE_FROMTIMESTAMP_METHODDEF    \
     {"fromtimestamp", (PyCFunction)datetime_date_fromtimestamp, METH_O|METH_CLASS, datetime_date_fromtimestamp__doc__},
 
+static PyObject *
+iso_calendar_date_new_impl(PyTypeObject *type, PyObject *seq);
+
+static PyObject *
+iso_calendar_date_new(PyTypeObject *type, PyObject *args, PyObject *kwargs)
+{
+    PyObject *return_value = NULL;
+    static const char * const _keywords[] = {"sequence", NULL};
+    static _PyArg_Parser _parser = {NULL, _keywords, "IsoCalendarDate", 0};
+    PyObject *argsbuf[1];
+    PyObject * const *fastargs;
+    Py_ssize_t nargs = PyTuple_GET_SIZE(args);
+    PyObject *seq;
+
+    fastargs = _PyArg_UnpackKeywords(_PyTuple_CAST(args)->ob_item, nargs, kwargs, NULL, &_parser, 1, 1, 0, argsbuf);
+    if (!fastargs) {
+        goto exit;
+    }
+    seq = fastargs[0];
+    return_value = iso_calendar_date_new_impl(type, seq);
+
+exit:
+    return return_value;
+}
+
 PyDoc_STRVAR(datetime_datetime_now__doc__,
 "now($type, /, tz=None)\n"
 "--\n"
@@ -55,4 +80,4 @@ datetime_datetime_now(PyTypeObject *type, PyObject *const *args, Py_ssize_t narg
 exit:
     return return_value;
 }
-/*[clinic end generated code: output=aae916ab728ca85b input=a9049054013a1b77]*/
+/*[clinic end generated code: output=48b1aa60aca63a57 input=a9049054013a1b77]*/

From 8584bf69ae41b8ad8fd1c4578f2f6a19b9977311 Mon Sep 17 00:00:00 2001
From: Dong-hee Na <donghee.na92@gmail.com>
Date: Sun, 22 Sep 2019 01:02:50 +0900
Subject: [PATCH 17/20] bpo-24416: Change pickling behavior of isocalendar()
 objects

---
 Lib/datetime.py            |  9 +++++++--
 Lib/test/datetimetester.py |  3 +--
 Modules/_datetimemodule.c  | 25 +++++++++++++++++++++----
 3 files changed, 29 insertions(+), 8 deletions(-)

diff --git a/Lib/datetime.py b/Lib/datetime.py
index dc55013d1cf860..c5bf4c74609144 100644
--- a/Lib/datetime.py
+++ b/Lib/datetime.py
@@ -1120,7 +1120,7 @@ def isocalendar(self):
             if today >= _isoweek1monday(year+1):
                 year += 1
                 week = 0
-        return IsoCalendarDate((year, week+1, day+1))
+        return _IsoCalendarDate((year, week+1, day+1))
 
     # Pickle support.
 
@@ -1231,11 +1231,16 @@ def week(self):
     def weekday(self):
         return self[2]
 
+    def __reduce__(self):
+        return (tuple, (tuple(self),))
+
     def __repr__(self):
         return (f'{self.__class__.__name__}'
             f'(year={self[0]}, week={self[1]}, weekday={self[2]})')
 
 
+_IsoCalendarDate = IsoCalendarDate
+del IsoCalendarDate
 _tzinfo_class = tzinfo
 
 class time:
@@ -2541,7 +2546,7 @@ def _name_from_offset(delta):
          _format_time, _format_offset, _is_leap, _isoweek1monday, _math,
          _ord2ymd, _time, _time_class, _tzinfo_class, _wrap_strftime, _ymd2ord,
          _divide_and_round, _parse_isoformat_date, _parse_isoformat_time,
-         _parse_hh_mm_ss_ff)
+         _parse_hh_mm_ss_ff, _IsoCalendarDate)
     # XXX Since import * above excludes names that start with _,
     # docstring does not get overwritten. In the future, it may be
     # appropriate to maintain a single module level docstring and
diff --git a/Lib/test/datetimetester.py b/Lib/test/datetimetester.py
index 990ff504bade72..959fc88b183433 100644
--- a/Lib/test/datetimetester.py
+++ b/Lib/test/datetimetester.py
@@ -77,8 +77,7 @@ def test_name_cleanup(self):
         names = set(name for name in dir(datetime)
                     if not name.startswith('__') and not name.endswith('__'))
         allowed = set(['MAXYEAR', 'MINYEAR', 'date', 'datetime',
-                       'datetime_CAPI', 'IsoCalendarDate',
-                       'time', 'timedelta', 'timezone',
+                       'datetime_CAPI', 'time', 'timedelta', 'timezone',
                        'tzinfo', 'sys'])
         self.assertEqual(names - allowed, set([]))
 
diff --git a/Modules/_datetimemodule.c b/Modules/_datetimemodule.c
index 64c2c8b7b11821..e9d6a5084fe83c 100644
--- a/Modules/_datetimemodule.c
+++ b/Modules/_datetimemodule.c
@@ -3257,6 +3257,20 @@ iso_calendar_date_repr(PyDateTime_IsoCalendarDate *self)
                                Py_TYPE(self)->tp_name, year, week, weekday);
 }
 
+static PyObject *
+isocalendardate_reduce(PyObject *self, PyObject *Py_UNUSED(ignored))
+{
+    // Construct the tuple that this reduces to
+    PyObject * reduce_tuple = Py_BuildValue(
+        "O((OOO))", &PyTuple_Type,
+        PyTuple_GET_ITEM(self, 0),
+        PyTuple_GET_ITEM(self, 1),
+        PyTuple_GET_ITEM(self, 2)
+    );
+
+    return reduce_tuple;
+}
+
 static PyObject *
 iso_calendar_date_year(PyDateTime_IsoCalendarDate *self, void *unused)
 {
@@ -3297,6 +3311,12 @@ static PyGetSetDef iso_calendar_date_getset[] = {
     {NULL}
 };
 
+static PyMethodDef iso_calendar_date_methods[] = {
+    {"__reduce__", (PyCFunction)isocalendardate_reduce, METH_NOARGS,
+     PyDoc_STR("__reduce__() -> (cls, state)")},
+    {NULL, NULL},
+};
+
 static PyTypeObject PyDateTime_IsoCalendarDateType = {
     PyVarObject_HEAD_INIT(NULL, 0)
     "datetime.IsoCalendarDate",                         /* tp_name */
@@ -3325,7 +3345,7 @@ static PyTypeObject PyDateTime_IsoCalendarDateType = {
     0,                                                  /* tp_weaklistoffset */
     0,                                                  /* tp_iter */
     0,                                                  /* tp_iternext */
-    0,                                                  /* tp_methods */
+    iso_calendar_date_methods,                          /* tp_methods */
     0,                                                  /* tp_members */
     iso_calendar_date_getset,                           /* tp_getset */
     &PyTuple_Type,                                      /* tp_base */
@@ -6687,9 +6707,6 @@ PyInit__datetime(void)
     PyModule_AddObject(m, "datetime",
                        (PyObject *)&PyDateTime_DateTimeType);
 
-    Py_INCREF((PyObject *) &PyDateTime_IsoCalendarDateType);
-    PyModule_AddObject(m, "IsoCalendarDate", (PyObject *) &PyDateTime_IsoCalendarDateType);
-
     Py_INCREF(&PyDateTime_TimeType);
     PyModule_AddObject(m, "time", (PyObject *) &PyDateTime_TimeType);
 

From 17104d5d94aa099a3cf3e20cb6be3146db2e293a Mon Sep 17 00:00:00 2001
From: Dong-hee Na <donghee.na92@gmail.com>
Date: Mon, 23 Sep 2019 02:42:10 +0900
Subject: [PATCH 18/20] bpo-24416: Update __new__

---
 Lib/datetime.py                    |  9 ++---
 Modules/_datetimemodule.c          | 54 +++++++++++-------------------
 Modules/clinic/_datetimemodule.c.h | 45 ++++++++++++++++++++-----
 3 files changed, 59 insertions(+), 49 deletions(-)

diff --git a/Lib/datetime.py b/Lib/datetime.py
index c5bf4c74609144..c4feec1ab83fe7 100644
--- a/Lib/datetime.py
+++ b/Lib/datetime.py
@@ -1120,7 +1120,7 @@ def isocalendar(self):
             if today >= _isoweek1monday(year+1):
                 year += 1
                 week = 0
-        return _IsoCalendarDate((year, week+1, day+1))
+        return _IsoCalendarDate(year, week+1, day+1)
 
     # Pickle support.
 
@@ -1213,11 +1213,8 @@ def __reduce__(self):
 
 class IsoCalendarDate(tuple):
 
-    def __new__(cls, seq):
-        if len(seq) != 3:
-            raise TypeError(f'{cls.__name__}() takes a 3-sequence '
-                    f'({len(seq)}-sequence given)')
-        return super().__new__(cls, seq)
+    def __new__(cls, year, week, weekday):
+        return super().__new__(cls, (year, week, weekday))
 
     @property
     def year(self):
diff --git a/Modules/_datetimemodule.c b/Modules/_datetimemodule.c
index e9d6a5084fe83c..0ad61b3df1120e 100644
--- a/Modules/_datetimemodule.c
+++ b/Modules/_datetimemodule.c
@@ -3274,8 +3274,8 @@ isocalendardate_reduce(PyObject *self, PyObject *Py_UNUSED(ignored))
 static PyObject *
 iso_calendar_date_year(PyDateTime_IsoCalendarDate *self, void *unused)
 {
-    PyObject* year =  PyTuple_GetItem((PyObject *)self, 0);
-    if(year == NULL) {
+    PyObject *year = PyTuple_GetItem((PyObject *)self, 0);
+    if (year == NULL) {
         return NULL;
     }
     Py_INCREF(year);
@@ -3285,7 +3285,7 @@ iso_calendar_date_year(PyDateTime_IsoCalendarDate *self, void *unused)
 static PyObject *
 iso_calendar_date_week(PyDateTime_IsoCalendarDate *self, void *unused)
 {
-    PyObject* week =  PyTuple_GetItem((PyObject *)self, 1);
+    PyObject *week = PyTuple_GetItem((PyObject *)self, 1);
     if (week == NULL) {
         return NULL;
     }
@@ -3296,8 +3296,8 @@ iso_calendar_date_week(PyDateTime_IsoCalendarDate *self, void *unused)
 static PyObject *
 iso_calendar_date_weekday(PyDateTime_IsoCalendarDate *self, void *unused)
 {
-    PyObject* weekday =  PyTuple_GetItem((PyObject *)self, 2);
-    if(weekday == NULL) {
+    PyObject *weekday = PyTuple_GetItem((PyObject *)self, 2);
+    if (weekday == NULL) {
         return NULL;
     }
     Py_INCREF(weekday);
@@ -3361,36 +3361,26 @@ static PyTypeObject PyDateTime_IsoCalendarDateType = {
 /*[clinic input]
 @classmethod
 datetime.IsoCalendarDate.__new__ as iso_calendar_date_new
-    sequence as seq: object
+    year: int
+    week: int
+    weekday: int
 [clinic start generated code]*/
 
 static PyObject *
-iso_calendar_date_new_impl(PyTypeObject *type, PyObject *seq)
-/*[clinic end generated code: output=bf2e1982e7012dae input=f9bb6626d4947edc]*/
-{
-    PyDateTime_IsoCalendarDate* self;
-    Py_ssize_t len = PyObject_Length(seq);
-    if (len == -1) {
-        return NULL;
-    }
-
-    if (len != 3) {
-        PyErr_Format(PyExc_TypeError,
-                     "%.500s() takes a 3-sequence (%zd-sequence given)",
-                     type->tp_name, len);
-        return NULL;
-    }
+iso_calendar_date_new_impl(PyTypeObject *type, int year, int week,
+                           int weekday)
+/*[clinic end generated code: output=383d33d8dc7183a2 input=4f2c663c9d19c4ee]*/
 
-    self = (PyDateTime_IsoCalendarDate *) type->tp_alloc(type, len);
+{
+    PyDateTime_IsoCalendarDate *self;
+    self = (PyDateTime_IsoCalendarDate *) type->tp_alloc(type, 3);
     if (self == NULL) {
         return NULL;
     }
 
-    for (int i = 0; i < len; ++i) {
-        PyObject* v = PyTuple_GetItem(seq, i);
-        Py_INCREF(v);
-        PyTuple_SET_ITEM(self, i, v);
-    }
+    PyTuple_SET_ITEM(self, 0, PyLong_FromLong(year));
+    PyTuple_SET_ITEM(self, 1, PyLong_FromLong(week));
+    PyTuple_SET_ITEM(self, 2, PyLong_FromLong(weekday));
 
     return (PyObject *)self;
 }
@@ -3415,17 +3405,11 @@ date_isocalendar(PyDateTime_Date *self, PyObject *Py_UNUSED(ignored))
         week = 0;
     }
 
-    PyObject *seq = Py_BuildValue("iii", year, week + 1, day + 1);
-    if (seq == NULL) {
-        return NULL;
-    }
-
-    PyObject* v = iso_calendar_date_new_impl(&PyDateTime_IsoCalendarDateType, seq);
+    PyObject* v = iso_calendar_date_new_impl(&PyDateTime_IsoCalendarDateType,
+                    year, week + 1, day + 1);
     if(v == NULL) {
-        Py_DECREF(seq);
         return NULL;
     }
-    Py_DECREF(seq);
     return v;
 }
 
diff --git a/Modules/clinic/_datetimemodule.c.h b/Modules/clinic/_datetimemodule.c.h
index 6f121ad72d5b88..973a4ea025347f 100644
--- a/Modules/clinic/_datetimemodule.c.h
+++ b/Modules/clinic/_datetimemodule.c.h
@@ -15,25 +15,54 @@ PyDoc_STRVAR(datetime_date_fromtimestamp__doc__,
     {"fromtimestamp", (PyCFunction)datetime_date_fromtimestamp, METH_O|METH_CLASS, datetime_date_fromtimestamp__doc__},
 
 static PyObject *
-iso_calendar_date_new_impl(PyTypeObject *type, PyObject *seq);
+iso_calendar_date_new_impl(PyTypeObject *type, int year, int week,
+                           int weekday);
 
 static PyObject *
 iso_calendar_date_new(PyTypeObject *type, PyObject *args, PyObject *kwargs)
 {
     PyObject *return_value = NULL;
-    static const char * const _keywords[] = {"sequence", NULL};
+    static const char * const _keywords[] = {"year", "week", "weekday", NULL};
     static _PyArg_Parser _parser = {NULL, _keywords, "IsoCalendarDate", 0};
-    PyObject *argsbuf[1];
+    PyObject *argsbuf[3];
     PyObject * const *fastargs;
     Py_ssize_t nargs = PyTuple_GET_SIZE(args);
-    PyObject *seq;
+    int year;
+    int week;
+    int weekday;
 
-    fastargs = _PyArg_UnpackKeywords(_PyTuple_CAST(args)->ob_item, nargs, kwargs, NULL, &_parser, 1, 1, 0, argsbuf);
+    fastargs = _PyArg_UnpackKeywords(_PyTuple_CAST(args)->ob_item, nargs, kwargs, NULL, &_parser, 3, 3, 0, argsbuf);
     if (!fastargs) {
         goto exit;
     }
-    seq = fastargs[0];
-    return_value = iso_calendar_date_new_impl(type, seq);
+    if (PyFloat_Check(fastargs[0])) {
+        PyErr_SetString(PyExc_TypeError,
+                        "integer argument expected, got float" );
+        goto exit;
+    }
+    year = _PyLong_AsInt(fastargs[0]);
+    if (year == -1 && PyErr_Occurred()) {
+        goto exit;
+    }
+    if (PyFloat_Check(fastargs[1])) {
+        PyErr_SetString(PyExc_TypeError,
+                        "integer argument expected, got float" );
+        goto exit;
+    }
+    week = _PyLong_AsInt(fastargs[1]);
+    if (week == -1 && PyErr_Occurred()) {
+        goto exit;
+    }
+    if (PyFloat_Check(fastargs[2])) {
+        PyErr_SetString(PyExc_TypeError,
+                        "integer argument expected, got float" );
+        goto exit;
+    }
+    weekday = _PyLong_AsInt(fastargs[2]);
+    if (weekday == -1 && PyErr_Occurred()) {
+        goto exit;
+    }
+    return_value = iso_calendar_date_new_impl(type, year, week, weekday);
 
 exit:
     return return_value;
@@ -80,4 +109,4 @@ datetime_datetime_now(PyTypeObject *type, PyObject *const *args, Py_ssize_t narg
 exit:
     return return_value;
 }
-/*[clinic end generated code: output=48b1aa60aca63a57 input=a9049054013a1b77]*/
+/*[clinic end generated code: output=5e17549f29a439a5 input=a9049054013a1b77]*/

From f04b6bcaf1bcef5d0cac8a919f171bbe34a3588e Mon Sep 17 00:00:00 2001
From: Dong-hee Na <donghee.na92@gmail.com>
Date: Mon, 23 Sep 2019 03:00:54 +0900
Subject: [PATCH 19/20] bpo-24416: Update whatsnew

---
 Doc/whatsnew/3.9.rst      | 1 -
 Modules/_datetimemodule.c | 2 +-
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/Doc/whatsnew/3.9.rst b/Doc/whatsnew/3.9.rst
index 706e171f53b979..2f70ef69e52fab 100644
--- a/Doc/whatsnew/3.9.rst
+++ b/Doc/whatsnew/3.9.rst
@@ -150,7 +150,6 @@ datetime
 The :meth:`~datetime.date.isocalendar()` of :class:`datetime.date`
 and :meth:`~datetime.datetime.isocalendar()` of :class:`datetime.datetime`
 methods now returns a :func:`~collections.namedtuple` instead of a :class:`tuple`.
-It can't be unpickled in previous versions.
 (Contributed by Dong-hee Na in :issue:`24416`.)
 
 fcntl
diff --git a/Modules/_datetimemodule.c b/Modules/_datetimemodule.c
index 0ad61b3df1120e..a617fe278aff9c 100644
--- a/Modules/_datetimemodule.c
+++ b/Modules/_datetimemodule.c
@@ -3407,7 +3407,7 @@ date_isocalendar(PyDateTime_Date *self, PyObject *Py_UNUSED(ignored))
 
     PyObject* v = iso_calendar_date_new_impl(&PyDateTime_IsoCalendarDateType,
                     year, week + 1, day + 1);
-    if(v == NULL) {
+    if (v == NULL) {
         return NULL;
     }
     return v;

From 0b04d4584cc374b381d869b14372abd5ddc74d22 Mon Sep 17 00:00:00 2001
From: Dong-hee Na <donghee.na92@gmail.com>
Date: Mon, 16 Dec 2019 17:15:29 +0900
Subject: [PATCH 20/20] bpo-24416: Apply vstinner's review

---
 Lib/datetime.py            | 4 +++-
 Lib/test/datetimetester.py | 8 +++-----
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/Lib/datetime.py b/Lib/datetime.py
index c4feec1ab83fe7..b39cc0d9703ad8 100644
--- a/Lib/datetime.py
+++ b/Lib/datetime.py
@@ -1229,11 +1229,13 @@ def weekday(self):
         return self[2]
 
     def __reduce__(self):
+        # This code is intended to pickle the object without making the
+        # class public. See https://bugs.python.org/msg352381
         return (tuple, (tuple(self),))
 
     def __repr__(self):
         return (f'{self.__class__.__name__}'
-            f'(year={self[0]}, week={self[1]}, weekday={self[2]})')
+                f'(year={self[0]}, week={self[1]}, weekday={self[2]})')
 
 
 _IsoCalendarDate = IsoCalendarDate
diff --git a/Lib/test/datetimetester.py b/Lib/test/datetimetester.py
index 959fc88b183433..a9741d6d4062f4 100644
--- a/Lib/test/datetimetester.py
+++ b/Lib/test/datetimetester.py
@@ -1389,11 +1389,9 @@ def test_isocalendar_pickling(self):
         The result of a round trip should be a plain tuple.
         """
         d = self.theclass(2019, 1, 1)
-        f = io.BytesIO()
-        pickle.dump(d.isocalendar(), f)
-        f.seek(0)
-        res = pickle.load(f)
-
+        p = pickle.dumps(d.isocalendar())
+        res = pickle.loads(p)
+        self.assertEqual(type(res), tuple)
         self.assertEqual(res, (2019, 1, 2))
 
     def test_iso_long_years(self):