[python]第三方模块 python-dateutil：扩展并增强 datetime 模块的功能

pip install python-dateutil

# or
# download from https://pypi.python.org/pypi/python-dateutil
python setup.py install

>>> import datetime
>>> from dateutil.relativedelta import relativedelta
>>>
>>> today
datetime.date(2013, 6, 9)
>>>
>>> today + relativedelta(years=-1)
datetime.date(2012, 6, 9)
>>>
>>> today + relativedelta(months=-1)
datetime.date(2013, 5, 9)
>>>
>>> today + relativedelta(months=1)
datetime.date(2013, 7, 9)