Lib/calendar.py (part 2)

Source:

cpython 3.14 @ ab2d84fe1023/Lib/calendar.py ↗

This annotation covers calendar formatting. See lib_calendar_detail for Calendar, monthcalendar, itermonthdays, itermonthdates, and monthrange.

Map

Lines	Symbol	Role
1-80	TextCalendar.formatweek	Format one week row as a string
81-200	TextCalendar.formatmonth	Format a full month as a multiline string
201-340	TextCalendar.formatyear	Format all 12 months in a grid
341-460	HTMLCalendar	Subclass generating HTML table output
461-540	setfirstweekday / firstweekday	Module-level first-day-of-week setting
541-600	month_abbr / day_abbr / month_name / day_name	Locale-sensitive name arrays

Reading

TextCalendar.formatmonth

# CPython: Lib/calendar.py:240 formatmonth
class TextCalendar(Calendar):
    def formatmonth(self, theyear, themonth, w=0, l=0):
        """Return a month's calendar string, multi-week."""
        v = []
        a = v.append
        a(self.formatmonthname(theyear, themonth, 7 * (w + 1) - 1))
        a('\n' * l)
        a(self.formatweekheader(w))
        a('\n' * l)
        for week in self.monthdays2calendar(theyear, themonth):
            a(self.formatweek(week, w))
            a('\n' * l)
        return ''.join(v)

calendar.month(2024, 1) returns a multi-line string with week rows. w is the width of each day column (default 2), l is extra blank lines between rows.

HTMLCalendar

# CPython: Lib/calendar.py:340 HTMLCalendar
class HTMLCalendar(Calendar):
    """Generate HTML calendar tables.

    Each day cell has class 'mon', 'tue', ..., 'sun'.
    Weekend cells additionally have class 'sat' or 'sun'.
    Empty cells (outside the month) have class 'noday'.
    """
    def formatday(self, day, weekday):
        if day == 0:
            return '<td class="noday">&nbsp;</td>'
        return '<td class="%s">%d</td>' % (self.cssclasses[weekday], day)

    def formatmonth(self, theyear, themonth, withyear=True):
        v = []
        a = v.append
        a('<table border="0" cellpadding="0" cellspacing="0" class="month">')
        a('\n')
        a(self.formatmonthname(theyear, themonth, withyear=withyear))
        a('\n')
        a(self.formatweekheader())
        a('\n')
        for week in self.monthdays2calendar(theyear, themonth):
            a(self.formatweek(week))
            a('\n')
        a('</table>')
        a('\n')
        return ''.join(v)

HTMLCalendar().formatmonth(2024, 1) generates a <table> with <td class="mon">, <td class="sat"> etc. CSS classes allow styling weekdays differently.

month_abbr / day_abbr

# CPython: Lib/calendar.py:50 _localized_month/_localized_day
# month_abbr = ['', 'Jan', 'Feb', 'Mar', ..., 'Dec']  (index 0 unused)
# month_name = ['', 'January', ..., 'December']
# day_abbr   = ['Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat', 'Sun']
# day_name   = ['Monday', ..., 'Sunday']
#
# These are locale-sensitive: built from locale.nl_langinfo when available.

The empty string at index 0 of month_abbr allows 1-based month indexing: month_abbr[1] == 'Jan'.

setfirstweekday

# CPython: Lib/calendar.py:74 setfirstweekday
def setfirstweekday(firstweekday):
    """Set weekday (0=Monday, 6=Sunday) to use as first column."""
    if not MONDAY <= firstweekday <= SUNDAY:
        raise IllegalWeekdayError(firstweekday)
    _localized_day.firstweekday = firstweekday

calendar.setfirstweekday(6) makes Sunday the first column of the week, as used in US calendars. The locale module's calendar format (via LC_TIME) may also affect the starting day.

gopy notes

calendar is pure Python. TextCalendar and HTMLCalendar use module/calendar/module.go. month_abbr/day_abbr are initialized from time.Month.String() in Go. setfirstweekday sets a module-level variable checked by monthdays2calendar.