gh-148352: Add more colour to calendar CLI output

Doc/library/calendar.rst

@@ -756,6 +756,11 @@ The following options are accepted:
  By default, today's date is highlighted in color and can be
  :ref:`controlled using environment variables <using-on-controlling-color>`.
 
+.. versionchanged:: next
+ By default, the month is now also highlighted in color, and
+ the days of the week are also in color. This behavior can be
+ :ref:`controlled using environment variables <using-on-controlling-color>`.
+
 *HTML-mode options:*
 
 .. option:: --css CSS, -c CSS

Doc/whatsnew/3.15.rst

@@ -832,14 +832,19 @@ binascii
 calendar
 --------
 
-* Calendar pages generated by the :class:`calendar.HTMLCalendar` class now support
- dark mode and have been migrated to the HTML5 standard for improved accessibility.
- (Contributed by Jiahao Li and Hugo van Kemenade in :gh:`137634`.)
+* :mod:`calendar`'s :ref:`command-line <calendar-cli>` text output has more
+ color. This can be controlled with :ref:`environment variables
+ <using-on-controlling-color>`.
+ (Contributed by Hugo van Kemenade in :gh:`148352`.)
 
 * The :mod:`calendar`'s :ref:`command-line <calendar-cli>` HTML output now
  accepts the year-month option: ``python -m calendar -t html 2009 06``.
  (Contributed by Pål Grønås Drange in :gh:`140212`.)
 
+* Calendar pages generated by the :class:`calendar.HTMLCalendar` class now support
+ dark mode and have been migrated to the HTML5 standard for improved accessibility.
+ (Contributed by Jiahao Li and Hugo van Kemenade in :gh:`137634`.)
+
 
 collections
 -----------

Lib/_colorize.py

@@ -200,6 +200,14 @@ class Ast(ThemeSection):
  reset: str = ANSIColors.RESET
 
 
+@dataclass(frozen=True, kw_only=True)
+class Calendar(ThemeSection):
+ header: str = ANSIColors.BOLD
+ highlight: str = ANSIColors.BLACK + ANSIColors.BACKGROUND_YELLOW
+ weekday: str = ANSIColors.CYAN
+ reset: str = ANSIColors.RESET
+
+
 @dataclass(frozen=True, kw_only=True)
 class Difflib(ThemeSection):
  """A 'git diff'-like theme for `difflib.unified_diff`."""
@@ -459,6 +467,7 @@ class Theme:
  """
  argparse: Argparse = field(default_factory=Argparse)
  ast: Ast = field(default_factory=Ast)
+ calendar: Calendar = field(default_factory=Calendar)
  difflib: Difflib = field(default_factory=Difflib)
  fancycompleter: FancyCompleter = field(default_factory=FancyCompleter)
  http_server: HttpServer = field(default_factory=HttpServer)
@@ -476,6 +485,7 @@ def copy_with(
  *,
  argparse: Argparse | None = None,
  ast: Ast | None = None,
+ calendar: Calendar | None = None,
  difflib: Difflib | None = None,
  fancycompleter: FancyCompleter | None = None,
  http_server: HttpServer | None = None,
@@ -496,6 +506,7 @@ def copy_with(
  return type(self)(
  argparse=argparse or self.argparse,
  ast=ast or self.ast,
+ calendar=calendar or self.calendar,
  difflib=difflib or self.difflib,
  fancycompleter=fancycompleter or self.fancycompleter,
  http_server=http_server or self.http_server,
@@ -520,6 +531,7 @@ def no_colors(cls) -> Self:
  return cls(
  argparse=Argparse.no_colors(),
  ast=Ast.no_colors(),
+ calendar=Calendar.no_colors(),
  difflib=Difflib.no_colors(),
  fancycompleter=FancyCompleter.no_colors(),
  http_server=HttpServer.no_colors(),

Lib/calendar.py

@@ -686,28 +686,61 @@ def __init__(self, highlight_day=None, *args, **kwargs):
  super().__init__(*args, **kwargs)
  self.highlight_day = highlight_day
 
- def formatweek(self, theweek, width, *, highlight_day=None):
+ def _get_theme(self):
+ from _colorize import get_theme
+
+ return get_theme(tty_file=sys.stdout)
+
+ def formatday(self, day, weekday, width, *, highlight_day=None):
  """
- Returns a single week in a string (no newline).
+ Returns a formatted day.
  """
- if highlight_day:
- from _colorize import get_colors
-
- ansi = get_colors()
- highlight = f"{ansi.BLACK}{ansi.BACKGROUND_YELLOW}"
- reset = ansi.RESET
+ if day == 0:
+ s = ''
  else:
- highlight = reset = ""
+ s = f'{day:2}'
+ s = s.center(width)
+ if day == highlight_day:
+ theme = self._get_theme().calendar
+ s = f"{theme.highlight}{s}{theme.reset}"
+ return s
 
+ def formatweek(self, theweek, width, *, highlight_day=None):
+ """
+ Returns a single week in a string (no newline).
+ """
  return ' '.join(
- (
- f"{highlight}{self.formatday(d, wd, width)}{reset}"
- if d == highlight_day
- else self.formatday(d, wd, width)
- )
+ self.formatday(d, wd, width, highlight_day=highlight_day)
  for (d, wd) in theweek
  )
 
+ def formatweekheader(self, width):
+ """
+ Return a header for a week.
+ """
+ header = super().formatweekheader(width)
+ theme = self._get_theme().calendar
+ return f"{theme.weekday}{header}{theme.reset}"
+
+ def formatmonthname(self, theyear, themonth, width, withyear=True):
+ """
+ Return a formatted month name.
+ """
+ name = super().formatmonthname(theyear, themonth, width, withyear)
+ theme = self._get_theme().calendar
+ if (
+ self.highlight_day
+ and self.highlight_day.year == theyear
+ and self.highlight_day.month == themonth
+ ):
+ color = theme.highlight
+ name_only = name.strip()
+ colored_name = f"{color}{name_only}{theme.reset}"
+ return name.replace(name_only, colored_name, 1)
+ else:
+ color = theme.header
+ return f"{color}{name}{theme.reset}"
+
  def formatmonth(self, theyear, themonth, w=0, l=0):
  """
  Return a month's calendar string (multi-line).
@@ -742,7 +775,9 @@ def formatyear(self, theyear, w=2, l=1, c=6, m=3):
  colwidth = (w + 1) * 7 - 1
  v = []
  a = v.append
- a(repr(theyear).center(colwidth*m+c*(m-1)).rstrip())
+ theme = self._get_theme().calendar
+ year = repr(theyear).center(colwidth*m+c*(m-1)).rstrip()
+ a(f"{theme.header}{year}{theme.reset}")
  a('\n'*l)
  header = self.formatweekheader(w)
  for (i, row) in enumerate(self.yeardays2calendar(theyear, m)):
@@ -843,28 +878,30 @@ def timegm(tuple):
 
 def main(args=None):
  import argparse
- parser = argparse.ArgumentParser(color=True)
+ parser = argparse.ArgumentParser(
+ formatter_class=argparse.ArgumentDefaultsHelpFormatter,
+ )
  textgroup = parser.add_argument_group('text only arguments')
  htmlgroup = parser.add_argument_group('html only arguments')
  textgroup.add_argument(
  "-w", "--width",
  type=int, default=2,
- help="width of date column (default 2)"
+ help="width of date column"
  )
  textgroup.add_argument(
  "-l", "--lines",
  type=int, default=1,
- help="number of lines for each week (default 1)"
+ help="number of lines for each week"
  )
  textgroup.add_argument(
  "-s", "--spacing",
  type=int, default=6,
- help="spacing between months (default 6)"
+ help="spacing between months"
  )
  textgroup.add_argument(
  "-m", "--months",
  type=int, default=3,
- help="months per row (default 3)"
+ help="months per row"
  )
  htmlgroup.add_argument(
  "-c", "--css",
@@ -879,7 +916,7 @@ def main(args=None):
  parser.add_argument(
  "-e", "--encoding",
  default=None,
- help="encoding to use for output (default utf-8)"
+ help="encoding to use for output"
  )
  parser.add_argument(
  "-t", "--type",
@@ -890,7 +927,7 @@ def main(args=None):
  parser.add_argument(
  "-f", "--first-weekday",
  type=int, default=0,
- help="weekday (0 is Monday, 6 is Sunday) to start each week (default 0)"
+ help="weekday (0 is Monday, 6 is Sunday) to start each week"
  )
  parser.add_argument(
  "year",

Lib/test/test_calendar.py

@@ -1068,6 +1068,7 @@ def test_several_leapyears_in_range(self):
 def conv(s):
  return s.replace('\n', os.linesep).encode()
 
+@support.force_not_colorized_test_class
 class CommandLineTestCase(unittest.TestCase):
  def setUp(self):
  self.runners = [self.run_cli_ok, self.run_cmd_ok]
@@ -1121,7 +1122,6 @@ def assertFailure(self, *args):
  self.assertCLIFails(*args)
  self.assertCmdFails(*args)
 
- @support.force_not_colorized
  def test_help(self):
  stdout = self.run_cmd_ok('-h')
  self.assertIn(b'usage:', stdout)
@@ -1256,6 +1256,15 @@ def test_html_output_year_css(self):
  self.assertIn(b'<link rel="stylesheet" href="custom.css">', output)
 
 
+@support.force_colorized_test_class
+class ColorTestCase(unittest.TestCase):
+ def test_formatmonth_color(self):
+ today = datetime.date(2026, 5, 4)
+ cal = calendar._CLIDemoCalendar(highlight_day=today)
+ output = cal.formatmonth(2026, 5)
+ self.assertIn("\x1b[30m\x1b[43mMay 2026\x1b[0m\n\x1b[36m", output)
+
+
 class MiscTestCase(unittest.TestCase):
  def test__all__(self):
  not_exported = {

Misc/NEWS.d/next/Library/2026-04-10-20-23-22.gh-issue-148352.lrec3W.rst

@@ -0,0 +1 @@
+Add more color to :mod:`calendar`'s CLI output. Patch by Hugo van Kemenade.