gh-118948: add support for ISO 8601 basic format to datetime

Doc/library/datetime.rst

@@ -772,13 +772,25 @@ Instance methods:
    .. versionchanged:: 3.9
       Result changed from a tuple to a :term:`named tuple`.
 
-.. method:: date.isoformat()
 
-   Return a string representing the date in ISO 8601 format, ``YYYY-MM-DD``::
+.. method:: date.isoformat(basic=False)
+
+   Return a string representing the date in:
+
+   - ISO 8601 extended format ``YYYY-MM-DD`` (the default), or
+   - ISO 8601 basic format ``YYYYMMDD`` via the *basic* argument.
+
+   Examples:
 
        >>> from datetime import date
        >>> date(2002, 12, 4).isoformat()
        '2002-12-04'
+       >>> date(2002, 12, 4).isoformat(basic=True)
+       '20021204'
+
+   .. versionchanged:: next
+      Added the *basic* parameter.
+
 
 .. method:: date.__str__()
 
@@ -1536,9 +1548,9 @@ Instance methods:
    and ``weekday``. The same as ``self.date().isocalendar()``.
 
 
-.. method:: datetime.isoformat(sep='T', timespec='auto')
+.. method:: datetime.isoformat(sep='T', timespec='auto', basic=False)
 
-   Return a string representing the date and time in ISO 8601 format:
+   Return a string representing the date and time in ISO 8601 extended format:
 
    - ``YYYY-MM-DDTHH:MM:SS.ffffff``, if :attr:`microsecond` is not 0
    - ``YYYY-MM-DDTHH:MM:SS``, if :attr:`microsecond` is 0
@@ -1550,13 +1562,20 @@ Instance methods:
      is not 0
    - ``YYYY-MM-DDTHH:MM:SS+HH:MM[:SS[.ffffff]]``,  if :attr:`microsecond` is 0
 
+   If *basic* is true, this uses the ISO 8601 basic format for the date,
+   time and offset components.
+
    Examples::
 
        >>> from datetime import datetime, timezone
        >>> datetime(2019, 5, 18, 15, 17, 8, 132263).isoformat()
        '2019-05-18T15:17:08.132263'
+       >>> datetime(2019, 5, 18, 15, 17, 8, 132263).isoformat(basic=True)
+       '20190518T151708.132263'
        >>> datetime(2019, 5, 18, 15, 17, tzinfo=timezone.utc).isoformat()
        '2019-05-18T15:17:00+00:00'
+       >>> datetime(2019, 5, 18, 15, 17, tzinfo=timezone.utc).isoformat(basic=True)
+       '20190518T151700+0000'
 
    The optional argument *sep* (default ``'T'``) is a one-character separator,
    placed between the date and time portions of the result. For example::
@@ -1603,6 +1622,9 @@ Instance methods:
    .. versionchanged:: 3.6
       Added the *timespec* parameter.
 
+   .. versionadded:: next
+      Added the *basic* parameter.
+
 
 .. method:: datetime.__str__()
 
@@ -1954,15 +1976,17 @@ Instance methods:
       Added the *fold* parameter.
 
 
-.. method:: time.isoformat(timespec='auto')
+.. method:: time.isoformat(timespec='auto', basic=False)
 
-   Return a string representing the time in ISO 8601 format, one of:
+   Return a string representing the time in ISO 8601 (extended) format, one of:
 
    - ``HH:MM:SS.ffffff``, if :attr:`microsecond` is not 0
    - ``HH:MM:SS``, if :attr:`microsecond` is 0
    - ``HH:MM:SS.ffffff+HH:MM[:SS[.ffffff]]``, if :meth:`utcoffset` does not return ``None``
    - ``HH:MM:SS+HH:MM[:SS[.ffffff]]``, if :attr:`microsecond` is 0 and :meth:`utcoffset` does not return ``None``
 
+   If *basic* is true, this uses the ISO 8601 basic format which omits the colons.
+
    The optional argument *timespec* specifies the number of additional
    components of the time to include (the default is ``'auto'``).
    It can be one of the following:
@@ -1997,6 +2021,9 @@ Instance methods:
    .. versionchanged:: 3.6
       Added the *timespec* parameter.
 
+   .. versionchanged:: next
+      Added the *basic* parameter.
+
 
 .. method:: time.__str__()
 

Doc/whatsnew/3.14.rst

@@ -786,6 +786,18 @@ operator
   (Contributed by Raymond Hettinger and Nico Mexis in :gh:`115808`.)
 
 
+datetime
+--------
+
+* Add support for the ISO 8601 basic format for the following methods:
+
+  - :meth:`date.isoformat <datetime.date.isoformat>`
+  - :meth:`datetime.isoformat <datetime.datetime.isoformat>`
+  - :meth:`time.isoformat <datetime.time.isoformat>`
+
+  (Contributed by Bénédikt Tran in :gh:`118948`.)
+
+
 os
 --
 

Lib/_pydatetime.py

@@ -163,14 +163,23 @@ def _build_struct_time(y, m, d, hh, mm, ss, dstflag):
     dnum = _days_before_month(y, m) + d
     return _time.struct_time((y, m, d, hh, mm, ss, wday, dnum, dstflag))
 
-def _format_time(hh, mm, ss, us, timespec='auto'):
-    specs = {
-        'hours': '{:02d}',
-        'minutes': '{:02d}:{:02d}',
-        'seconds': '{:02d}:{:02d}:{:02d}',
-        'milliseconds': '{:02d}:{:02d}:{:02d}.{:03d}',
-        'microseconds': '{:02d}:{:02d}:{:02d}.{:06d}'
-    }
+def _format_time(hh, mm, ss, us, timespec='auto', basic=False):
+    if basic:
+        specs = {
+            'hours': '{:02d}',
+            'minutes': '{:02d}{:02d}',
+            'seconds': '{:02d}{:02d}{:02d}',
+            'milliseconds': '{:02d}{:02d}{:02d}.{:03d}',
+            'microseconds': '{:02d}{:02d}{:02d}.{:06d}'
+        }
+    else:
+        specs = {
+            'hours': '{:02d}',
+            'minutes': '{:02d}:{:02d}',
+            'seconds': '{:02d}:{:02d}:{:02d}',
+            'milliseconds': '{:02d}:{:02d}:{:02d}.{:03d}',
+            'microseconds': '{:02d}:{:02d}:{:02d}.{:06d}'
+        }
 
     if timespec == 'auto':
         # Skip trailing microseconds when us==0.
@@ -1117,16 +1126,18 @@ def __format__(self, fmt):
             return self.strftime(fmt)
         return str(self)
 
-    def isoformat(self):
-        """Return the date formatted according to ISO.
+    def isoformat(self, basic=False):
+        """Return the date formatted according to ISO 8601.
 
-        This is 'YYYY-MM-DD'.
+        This is 'YYYY-MM-DD' or 'YYYYMMDD' if *basic* is true.
 
         References:
-        - http://www.w3.org/TR/NOTE-datetime
-        - http://www.cl.cam.ac.uk/~mgk25/iso-time.html
+        - https://www.w3.org/TR/NOTE-datetime
+        - https://www.cl.cam.ac.uk/~mgk25/iso-time.html
         """
-        return "%04d-%02d-%02d" % (self._year, self._month, self._day)
+        if basic:
+            return f"{self._year:04d}{self._month:02d}{self._day:02d}"
+        return f"{self._year:04d}-{self._month:02d}-{self._day:02d}"
 
     __str__ = isoformat
 
@@ -1574,10 +1585,13 @@ def __hash__(self):
 
     # Conversion to string
 
-    def _tzstr(self):
-        """Return formatted timezone offset (+xx:xx) or an empty string."""
+    def _tzstr(self, basic):
+        """Return formatted timezone offset (+xx:xx) or an empty string.
+        The colon separator is omitted if *basic* is true.
+        """
         off = self.utcoffset()
-        return _format_offset(off)
+        sep = '' if basic else ':'
+        return _format_offset(off, sep)
 
     def __repr__(self):
         """Convert to formal string, for repr()."""
@@ -1598,19 +1612,21 @@ def __repr__(self):
             s = s[:-1] + ", fold=1)"
         return s
 
-    def isoformat(self, timespec='auto'):
+    def isoformat(self, timespec='auto', basic=False):
         """Return the time formatted according to ISO.
 
         The full format is 'HH:MM:SS.mmmmmm+zz:zz'. By default, the fractional
         part is omitted if self.microsecond == 0.
 
+        If *basic* is true, separators ':' are omitted.
+
         The optional argument timespec specifies the number of additional
         terms of the time to include. Valid options are 'auto', 'hours',
         'minutes', 'seconds', 'milliseconds' and 'microseconds'.
         """
         s = _format_time(self._hour, self._minute, self._second,
-                          self._microsecond, timespec)
-        tz = self._tzstr()
+                         self._microsecond, timespec, basic)
+        tz = self._tzstr(basic)
         if tz:
             s += tz
         return s
@@ -2118,6 +2134,14 @@ def astimezone(self, tz=None):
 
     # Ways to produce a string.
 
+    def _tzstr(self, basic):
+        """Return formatted timezone offset (+xx:xx) or an empty string.
+        The colon separator is omitted if *basic* is true.
+        """
+        off = self.utcoffset()
+        sep = '' if basic else ':'
+        return _format_offset(off, sep)
+
     def ctime(self):
         "Return ctime() style string."
         weekday = self.toordinal() % 7 or 7
@@ -2128,12 +2152,14 @@ def ctime(self):
             self._hour, self._minute, self._second,
             self._year)
 
-    def isoformat(self, sep='T', timespec='auto'):
+    def isoformat(self, sep='T', timespec='auto', basic=False):
         """Return the time formatted according to ISO.
 
         The full format looks like 'YYYY-MM-DD HH:MM:SS.mmmmmm'.
         By default, the fractional part is omitted if self.microsecond == 0.
 
+        If *basic* is true, separators ':' and '-' are omitted.
+
         If self.tzinfo is not None, the UTC offset is also attached, giving
         giving a full format of 'YYYY-MM-DD HH:MM:SS.mmmmmm+HH:MM'.
 
@@ -2144,12 +2170,12 @@ def isoformat(self, sep='T', timespec='auto'):
         terms of the time to include. Valid options are 'auto', 'hours',
         'minutes', 'seconds', 'milliseconds' and 'microseconds'.
         """
-        s = ("%04d-%02d-%02d%c" % (self._year, self._month, self._day, sep) +
+        fmt = "%04d%02d%02d%c" if basic else "%04d-%02d-%02d%c"
+        s = (fmt % (self._year, self._month, self._day, sep) +
              _format_time(self._hour, self._minute, self._second,
-                          self._microsecond, timespec))
+                          self._microsecond, timespec, basic))
 
-        off = self.utcoffset()
-        tz = _format_offset(off)
+        tz = self._tzstr(basic)
         if tz:
             s += tz