Add a way to convert datetime to UTC before formatting (#128)

CHANGELOG.rst

@@ -3,9 +3,10 @@
 
 - Fix incompatibility with ``multiprocessing`` on Windows by entirely refactoring the internal structure of the ``logger`` so it can be inherited by child processes along with added handlers (`#108 <https://github.com/Delgan/loguru/issues/108>`_).
 - Fix an error using a ``filter`` function "by name" while receiving a log with ``record["name"]`` equals to ``None``.
-- Fix ``AttributeError`` while using a file sink on some distributions (like Alpine Linux) missing the ``os.getxattr`` and ``os.setxattr`` functions (`#34 <https://github.com/Delgan/loguru/pull/158>`_, thanks `@joshgordon <https://github.com/joshgordon>`_).
+- Fix ``AttributeError`` while using a file sink on some distributions (like Alpine Linux) missing the ``os.getxattr`` and ``os.setxattr`` functions (`#158 <https://github.com/Delgan/loguru/pull/158>`_, thanks `@joshgordon <https://github.com/joshgordon>`_).
 - Add support for ``copy.deepcopy()`` of the ``logger`` allowing multiple independent loggers with separate set of handlers (`#72 <https://github.com/Delgan/loguru/issues/72>`_).
 - Prevent hypothetical ``ImportError`` if a Python installation is missing the built-in ``distutils`` module (`#118 <https://github.com/Delgan/loguru/issues/118>`_).
+- Add the possibility to convert ``datetime`` to UTC before formatting (in logs and filenames) by adding ``"!UTC"`` at the end of the time format specifier (`#128 <https://github.com/Delgan/loguru/issues/128>`_).
 - Add the level ``name`` as the first argument of namedtuple returned by the ``.level()`` method.
 
 

loguru/_datetime.py

@@ -4,24 +4,31 @@
 from datetime import timedelta, timezone
 from time import localtime, strftime
 
+
 tokens = r"H{1,2}|h{1,2}|m{1,2}|s{1,2}|S{1,6}|YYYY|YY|M{1,4}|D{1,4}|Z{1,2}|zz|A|X|x|E|Q|dddd|ddd|d"
 
-pattern = re.compile(r"(?:{0})|\[(?:{0})\]".format(tokens))
+pattern = re.compile(r"(?:{0})|\[(?:{0}|!UTC)\]".format(tokens))
 
 
 class datetime(datetime_):
     def __format__(self, spec):
+        if spec.endswith("!UTC"):
+            dt = self.astimezone(timezone.utc)
+            spec = spec[:-4]
+        else:
+            dt = self
+
         if not spec:
             spec = "%Y-%m-%dT%H:%M:%S.%f%z"
 
         if "%" in spec:
-            return super().__format__(spec)
+            return datetime_.__format__(dt, spec)
 
-        year, month, day, hour, minute, second, weekday, yearday, _ = self.timetuple()
-        microsecond = self.microsecond
-        timestamp = self.timestamp()
-        tzinfo = self.tzinfo or timezone(timedelta(seconds=0))
-        offset = tzinfo.utcoffset(self).total_seconds()
+        year, month, day, hour, minute, second, weekday, yearday, _ = dt.timetuple()
+        microsecond = dt.microsecond
+        timestamp = dt.timestamp()
+        tzinfo = dt.tzinfo or timezone(timedelta(seconds=0))
+        offset = tzinfo.utcoffset(dt).total_seconds()
         sign = ("-", "+")[offset >= 0]
         h, m = divmod(abs(offset // 60), 60)
 
@@ -58,7 +65,7 @@ def __format__(self, spec):
             "A": ("AM", "PM")[hour // 12],
             "Z": "%s%02d:%02d" % (sign, h, m),
             "ZZ": "%s%02d%02d" % (sign, h, m),
-            "zz": tzinfo.tzname(self) or "",
+            "zz": tzinfo.tzname(dt) or "",
             "X": "%d" % timestamp,
             "x": "%d" % (int(timestamp) * 1000000 + microsecond),
         }

loguru/_logger.py

@@ -451,6 +451,10 @@ def add(
         of the one used by the `Pendulum`_ library of `@sdispater`_. To escape a token, just add
         square brackets around it, for example ``"[YY]"`` would display literally ``"YY"``.
 
+        If you prefer to display UTC rather than local time, you can add ``"!UTC"`` at the very end
+        of the time format, like ``{time:HH:mm:ss!UTC}``. Doing so will convert the ``datetime``
+        to UTC before formatting.
+
         If no time formatter specifier is used, like for example if ``format="{time} {message}"``,
         the default one will use ISO 8601.
 

tests/test_datetime.py

@@ -6,18 +6,54 @@
 import sys
 import re
 
+if sys.version_info < (3, 6):
+    UTC_NAME = "UTC+00:00"
+else:
+    UTC_NAME = "UTC"
+
+
 @pytest.mark.parametrize(
     "time_format, date, expected",
     [
         (
-            "%Y-%m-%d %H-%M-%S %f %Z",
+            "%Y-%m-%d %H-%M-%S %f %Z %z",
+            (2018, 6, 9, 1, 2, 3, 45, "UTC", 0),
+            "2018-06-09 01-02-03 000045 UTC +0000",
+        ),
+        (
+            "YYYY-MM-DD HH-mm-ss SSSSSS zz ZZ",
+            (2018, 6, 9, 1, 2, 3, 45, "UTC", 0),
+            "2018-06-09 01-02-03 000045 UTC +0000",
+        ),
+        (
+            "%Y-%m-%d %H-%M-%S %f %Z %z",
+            (2018, 6, 9, 1, 2, 3, 45, "EST", -18000),
+            "2018-06-09 01-02-03 000045 EST -0500",
+        ),
+        (
+            "YYYY-MM-DD HH-mm-ss SSSSSS zz ZZ",
+            (2018, 6, 9, 1, 2, 3, 45, "EST", -18000),
+            "2018-06-09 01-02-03 000045 EST -0500",
+        ),
+        (
+            "%Y-%m-%d %H-%M-%S %f %Z!UTC",
             (2018, 6, 9, 1, 2, 3, 45, "UTC", 0),
-            "2018-06-09 01-02-03 000045 UTC",
+            "2018-06-09 01-02-03 000045 %s" % UTC_NAME,
         ),
         (
-            "YYYY-MM-DD HH-mm-ss SSSSSS zz",
+            "YYYY-MM-DD HH-mm-ss SSSSSS zz!UTC",
             (2018, 6, 9, 1, 2, 3, 45, "UTC", 0),
-            "2018-06-09 01-02-03 000045 UTC",
+            "2018-06-09 01-02-03 000045 %s" % UTC_NAME,
+        ),
+        (
+            "%Y-%m-%d %H-%M-%S %f %Z %z!UTC",
+            (2018, 6, 9, 1, 2, 3, 45, "EST", -18000),
+            "2018-06-09 06-02-03 000045 %s +0000" % UTC_NAME,
+        ),
+        (
+            "YYYY-MM-DD HH-mm-ss SSSSSS zz ZZ!UTC",
+            (2018, 6, 9, 1, 2, 3, 45, "UTC", -18000),
+            "2018-06-09 06-02-03 000045 %s +0000" % UTC_NAME,
         ),
         ("YY-M-D H-m-s SSS Z", (2005, 4, 7, 9, 3, 8, 2320, "A", 3600), "05-4-7 9-3-8 002 +01:00"),
         (
@@ -31,6 +67,25 @@
         ("[YYYY] MM [DD]", (2018, 2, 3, 11, 9, 0, 2), "YYYY 02 DD"),
         ("[YYYY MM DD]", (2018, 1, 3, 11, 3, 4, 2), "[2018 01 03]"),
         ("[[YY]]", (2018, 1, 3, 11, 3, 4, 2), "[YY]"),
+        ("[]", (2018, 1, 3, 11, 3, 4, 2), "[]"),
+        #        ("[HHmmss", (2018, 1, 3, 11, 3, 4, 2), "[110304"),  # Fail PyPy
+        ("HHmmss]", (2018, 1, 3, 11, 3, 4, 2), "110304]"),
+        ("HH:mm:ss!UTC", (2018, 1, 1, 11, 30, 0, 0, "A", 7200), "09:30:00"),
+        ("UTC! HH:mm:ss", (2018, 1, 1, 11, 30, 0, 0, "A", 7200), "UTC! 11:30:00"),
+        ("!UTC HH:mm:ss", (2018, 1, 1, 11, 30, 0, 0, "A", 7200), "!UTC 11:30:00"),
+        (
+            "hh:mm:ss A - Z ZZ !UTC",
+            (2018, 1, 1, 12, 30, 0, 0, "A", 5400),
+            "11:00:00 AM - +00:00 +0000 ",
+        ),
+        (
+            "YYYY-MM-DD HH:mm:ss[Z]!UTC",
+            (2018, 1, 3, 11, 3, 4, 2, "XYZ", -7200),
+            "2018-01-03 13:03:04Z",
+        ),
+        ("HH:mm:ss[!UTC]", (2018, 1, 1, 11, 30, 0, 0, "A", 7200), "11:30:00!UTC"),
+        ("", (2018, 2, 3, 11, 9, 0, 2, "Z", 1800), "2018-02-03T11:09:00.000002+0030"),
+        ("!UTC", (2018, 2, 3, 11, 9, 0, 2, "Z", 1800), "2018-02-03T10:39:00.000002+0000"),
     ],
 )
 def test_formatting(writer, monkeypatch_date, time_format, date, expected):
@@ -69,9 +124,7 @@ def test_file_formatting(monkeypatch_date, tmpdir):
 
 
 def test_missing_struct_time_fields(writer, monkeypatch, monkeypatch_date):
-
     class struct_time:
-
         def __init__(self, struct):
             self._struct = struct
 
@@ -80,7 +133,6 @@ def __getattr__(self, attr):
                 raise AttributeError
             return getattr(self._struct, attr)
 
-
     def localtime(*args, **kwargs):
         local = time.localtime(*args, **kwargs)
         return struct_time(local)