gh-103636: add enums for days and months in calendar module (GH-103642)

Convert day contants to a Day enum, and add a Month enum.

2 files changed, 40 insertions, 21 deletions

diff --git a/Lib/calendar.py b/Lib/calendar.py
index 6573964..c219f0c 100644
--- a/Lib/calendar.py
+++ b/Lib/calendar.py
@@ -7,6 +7,7 @@ set the first day of the week (0=Monday, 6=Sunday)."""
 
 import sys
 import datetime
+from enum import IntEnum, global_enum
 import locale as _locale
 from itertools import repeat
 
@@ -16,6 +17,9 @@ __all__ = ["IllegalMonthError", "IllegalWeekdayError", "setfirstweekday",
            "timegm", "month_name", "month_abbr", "day_name", "day_abbr",
            "Calendar", "TextCalendar", "HTMLCalendar", "LocaleTextCalendar",
            "LocaleHTMLCalendar", "weekheader",
+           "Day", "Month", "JANUARY", "FEBRUARY", "MARCH",
+           "APRIL", "MAY", "JUNE", "JULY",
+           "AUGUST", "SEPTEMBER", "OCTOBER", "NOVEMBER", "DECEMBER",
            "MONDAY", "TUESDAY", "WEDNESDAY", "THURSDAY", "FRIDAY",
            "SATURDAY", "SUNDAY"]
 
@@ -37,9 +41,35 @@ class IllegalWeekdayError(ValueError):
         return "bad weekday number %r; must be 0 (Monday) to 6 (Sunday)" % self.weekday
 
 
-# Constants for months referenced later
-January = 1
-February = 2
+# Constants for months
+@global_enum
+class Month(IntEnum):
+    JANUARY = 1
+    FEBRUARY = 2
+    MARCH = 3
+    APRIL = 4
+    MAY = 5
+    JUNE = 6
+    JULY = 7
+    AUGUST = 8
+    SEPTEMBER = 9
+    OCTOBER = 10
+    NOVEMBER = 11
+    DECEMBER = 12
+
+
+# Constants for days
+@global_enum
+class Day(IntEnum):
+    MONDAY = 0
+    TUESDAY = 1
+    WEDNESDAY = 2
+    THURSDAY = 3
+    FRIDAY = 4
+    SATURDAY = 5
+    SUNDAY = 6
+
+
 
 # Number of days per month (except for February in leap years)
 mdays = [0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31]
@@ -95,9 +125,6 @@ day_abbr = _localized_day('%a')
 month_name = _localized_month('%B')
 month_abbr = _localized_month('%b')
 
-# Constants for weekdays
-(MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, SATURDAY, SUNDAY) = range(7)
-
 
 def isleap(year):
     """Return True for leap years, False for non-leap years."""
@@ -125,12 +152,12 @@ def monthrange(year, month):
     if not 1 <= month <= 12:
         raise IllegalMonthError(month)
     day1 = weekday(year, month, 1)
-    ndays = mdays[month] + (month == February and isleap(year))
+    ndays = mdays[month] + (month == FEBRUARY and isleap(year))
     return day1, ndays
 
 
 def _monthlen(year, month):
-    return mdays[month] + (month == February and isleap(year))
+    return mdays[month] + (month == FEBRUARY and isleap(year))
 
 
 def _prevmonth(year, month):
@@ -260,10 +287,7 @@ class Calendar(object):
         Each month contains between 4 and 6 weeks and each week contains 1-7
         days. Days are datetime.date objects.
         """
-        months = [
-            self.monthdatescalendar(year, i)
-            for i in range(January, January+12)
-        ]
+        months = [self.monthdatescalendar(year, m) for m in Month]
         return [months[i:i+width] for i in range(0, len(months), width) ]
 
     def yeardays2calendar(self, year, width=3):
@@ -273,10 +297,7 @@ class Calendar(object):
         (day number, weekday number) tuples. Day numbers outside this month are
         zero.
         """
-        months = [
-            self.monthdays2calendar(year, i)
-            for i in range(January, January+12)
-        ]
+        months = [self.monthdays2calendar(year, m) for m in Month]
         return [months[i:i+width] for i in range(0, len(months), width) ]
 
     def yeardayscalendar(self, year, width=3):
@@ -285,10 +306,7 @@ class Calendar(object):
         yeardatescalendar()). Entries in the week lists are day numbers.
         Day numbers outside this month are zero.
         """
-        months = [
-            self.monthdayscalendar(year, i)
-            for i in range(January, January+12)
-        ]
+        months = [self.monthdayscalendar(year, m) for m in Month]
         return [months[i:i+width] for i in range(0, len(months), width) ]
 
 
@@ -509,7 +527,7 @@ class HTMLCalendar(Calendar):
         a('\n')
         a('<tr><th colspan="%d" class="%s">%s</th></tr>' % (
             width, self.cssclass_year_head, theyear))
-        for i in range(January, January+12, width):
+        for i in range(JANUARY, JANUARY+12, width):
             # months in this row
             months = range(i, min(i+width, 13))
             a('<tr>')
diff --git a/Misc/NEWS.d/next/Library/2023-04-21-10-25-39.gh-issue-103636.YK6NEa.rst b/Misc/NEWS.d/next/Library/2023-04-21-10-25-39.gh-issue-103636.YK6NEa.rst
new file mode 100644
index 0000000..b3b5085
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2023-04-21-10-25-39.gh-issue-103636.YK6NEa.rst
@@ -0,0 +1 @@
+Added Enum for months and days in the calendar module.