Returning same type as self for arithmetic in subclasses

[Max M]

# -*- coding: latin-1 -*-


"""
I subclass datetime and timedelta

 >>> dt = myDatetime(1970,1,1)
 >>> type(dt)
<class 'dtime.myDatetime'>

 >>> td = myTimedelta(hours=1)
 >>> type(td)
<class 'dtime.myTimedelta'>

But when I do arithmetic with these classes, they return datetime and 
timedelta,
where I want them to return myDatetime and myTimedelta

 >>> new_time = dt + td
 >>> new_time
datetime.datetime(1970, 1, 1, 1, 0)

 >>> type(new_time)
<type 'datetime.datetime'>

So I wondered if there was a simlpler way to coerce the result into my 
desired
types rather than overwriting the __add__, __sub__ etc. methods?

"""

from datetime import datetime, timedelta

class myDatetime(datetime):
     pass

class myTimedelta(timedelta):
     pass


if __name__ == "__main__":

     import os.path, doctest, dtime
     # import and test this file
     doctest.testmod(dtime)




-- 

hilsen/regards Max M, Denmark

http://www.mxm.dk/
IT's Mad Science