Python timezone conversion

timezone_conv.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-

"""timezoneの変換"""

import datetime

class UTC(datetime.tzinfo):
    def utcoffset(self, dt):
        return datetime.timedelta()
    def dst(self, dt):
        return datetime.timedelta()

class JST(datetime.tzinfo):
    def utcoffset(self, dt):
        return datetime.timedelta(hours=+9)
    def dst(self, dt):
        return datetime.timedelta()

d = datetime.datetime(2014, 1, 2, 9, 30, 5, tzinfo=JST())
print d.isoformat() # 2014-01-02T09:30:05+09:00

# astimezoneはtzinfoに従って時刻を変換する
d = d.astimezone(UTC())
print d.isoformat() # 2014-01-02T00:30:05+00:00

# replaceはtzinfoの単純置き換えで時刻は変換されない
d = d.replace(tzinfo=JST())
print d.isoformat() # 2014-01-02T00:30:05+09:00