Ticket #479: tzinfo.py

"""Implementation of a tzinfo-classes for use with datetime.datetime."""

import time
from datetime import timedelta, tzinfo

class FixedOffset(tzinfo):
    """Fixed offset in minutes east from UTC."""

    def __init__(self, offset):
        self.__offset = timedelta(minutes=offset)
        # FIXME -- Not really a name...
        self.__name = "%+03d%02d" % (offset / 60, offset % 60)

    def __repr__(self):
        return self.__name

    def utcoffset(self, dt):
        return self.__offset

    def tzname(self, dt):
        return self.__name

    def dst(self, dt):
        return ZERO

class LocalTimezone(tzinfo):
    """Proxy timezone information from time module."""
    def __init__(self, dt):
        tzinfo.__init__(self, dt)
        self._tzname = time.tzname[self._isdst(dt)]
    def __repr__(self):
        return self._tzname

    def utcoffset(self, dt):
        if self._isdst(dt):
            return timedelta(seconds=-time.altzone)
        else:
            return timedelta(seconds=-time.timezone)
    def dst(self, dt):
        if self._isdst(dt):
            return timedelta(seconds=-time.altzone) - timedelta(seconds=-time.timezone)
        else:
            return timedelta(0)
    def tzname(self, dt):
        return time.tzname[self._isdst(dt)]
    def _isdst(self, dt):
        tt = (dt.year, dt.month, dt.day,
              getattr(dt, 'hour', 0), getattr(dt, 'minute', 0), getattr(dt, 'second', 0),
              dt.weekday(), 0, -1)
        stamp = time.mktime(tt)
        tt = time.localtime(stamp)
        return tt.tm_isdst > 0