apptags.py 文件源码

def timezone_offset(timezone):
    """Takes a tz name like 'US/Eastern' and returns 'US/Eastern - UTC-05:00'.

    Intended to be used by the timezone notification page fragment.  The pytz
    package should gracefully handle DST so the above will render 'US/Eastern -
    UTC-04:00' when DST is in effect.
    """
    if timezone == 'UTC':
        return 'UTC'
    now = datetime.datetime.now()
    try:
        seconds = pytz.timezone(timezone).utcoffset(now).total_seconds()
    except (pytz.NonExistentTimeError, pytz.AmbiguousTimeError):
        # If we're in the midst of a DST transition, add an hour and try again.
        now = now + datetime.timedelta(hours=1)
        seconds = pytz.timezone(timezone).utcoffset(now).total_seconds()
    sign = '+'
    if seconds < 0:
        # The minus sign is added automatically!
        sign = ''
    hours, remainder = divmod(seconds, 60*60)
    minutes, _ = divmod(remainder, 60)
    offset = '%02d:%02d' % (hours, minutes)
    display = '%s (UTC%s%s)' % (timezone, sign, offset)
    return display