gh-135001: Explicitly specify the encoding parameter value of calendar.HTMLCalendar as 'utf-8'

Doc/library/calendar.rst

@@ -245,14 +245,16 @@ interpreted as prescribed by the ISO 8601 standard.  Year 0 is 1 BC, year -1 is
       specifies the number of months per row.
 
 
-   .. method:: formatyearpage(theyear, width=3, css='calendar.css', encoding=None)
+   .. method:: formatyearpage(theyear, width=3, css='calendar.css', encoding='utf-8')
 
       Return a year's calendar as a complete HTML page. *width* (defaulting to
       3) specifies the number of months per row. *css* is the name for the
       cascading style sheet to be used. :const:`None` can be passed if no style
       sheet should be used. *encoding* specifies the encoding to be used for the
-      output (defaulting to the system default encoding).
+      output (defaulting to ``utf-8``).
 
+      .. versionchanged:: next
+         The default value of the *encoding* has been changed to utf-8.
 
    .. method:: formatmonthname(theyear, themonth, withyear=True)
 
@@ -651,8 +653,10 @@ The following options are accepted:
 .. option:: --encoding ENCODING, -e ENCODING
 
    The encoding to use for output.
-   :option:`--encoding` is required if :option:`--locale` is set.
+   Defaults to utf-8.
 
+.. versionchanged:: next
+   The default value has been changed to utf-8.
 
 .. option:: --type {text,html}, -t {text,html}
 

Doc/whatsnew/3.15.rst

@@ -138,6 +138,13 @@ Deprecated
 Removed
 =======
 
+calendar
+--------
+
+* The default *encoding* parameter value in :meth:`calendar.HTMLCalendar.formatyearpage`
+  is now utf-8.
+  (Contributed by Jiahao Li in :gh:`135001`.)
+
 ctypes
 ------
 

Lib/calendar.py

@@ -560,12 +560,10 @@ def formatyear(self, theyear, width=3):
         a('</table>')
         return ''.join(v)
 
-    def formatyearpage(self, theyear, width=3, css='calendar.css', encoding=None):
+    def formatyearpage(self, theyear, width=3, css='calendar.css', encoding='utf-8'):
         """
         Return a formatted year as a complete HTML page.
         """
-        if encoding is None:
-            encoding = sys.getdefaultencoding()
         v = []
         a = v.append
         a('<?xml version="1.0" encoding="%s"?>\n' % encoding)
@@ -845,8 +843,8 @@ 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 (default utf-8)"
     )
     parser.add_argument(
         "-t", "--type",
@@ -872,10 +870,6 @@ def main(args=None):
 
     options = parser.parse_args(args)
 
-    if options.locale and not options.encoding:
-        parser.error("if --locale is specified --encoding is required")
-        sys.exit(1)
-
     locale = options.locale, options.encoding
     today = datetime.date.today()
 
@@ -889,8 +883,6 @@ def main(args=None):
             cal = HTMLCalendar()
         cal.setfirstweekday(options.first_weekday)
         encoding = options.encoding
-        if encoding is None:
-            encoding = sys.getdefaultencoding()
         optdict = dict(encoding=encoding, css=options.css)
         write = sys.stdout.buffer.write
         if options.year is None:

Misc/NEWS.d/next/Library/2025-06-01-19-45-55.gh-issue-135001.KsBXSl.rst

@@ -0,0 +1,2 @@
+The default *encoding* parameter value in
+:meth:`calendar.HTMLCalendar.formatyearpage` is now utf-8.