On Sun, Jan 22, 2012 at 10:22 PM, Massimo Di Pierro < massimo.dipie...@gmail.com> wrote:
> Hello everybody, > > I hope somebody could help me with this problem. If this is not the right > place to ask, please direct me to the right place and apologies. > I am using Python 2.7 and I am writing some code I want to work on 3.x as > well. The problem can be reproduced with this code: > > # from __future__ import division > class Number(object): > def __init__(self,number): > self.number=number > def __rdiv__(self,other): > return other/self.number > print 10/Number(5) > > It prints 2 as I expect. But if I uncomment the first line, I get: > > Traceback (most recent call last): > File "test.py", line 8, in <module> > print 10/Number(5) > TypeError: unsupported operand type(s) for /: 'int' and 'Number' > > Is this a bug or the __future__ division in 3.x changed the way operators > are overloaded? Where can I read more? > > In Python 3, the / operator uses __truediv__ and the // operator uses __floordiv__. In Python 2, the / operator uses __div__, unless the future import is in effect, and then it uses __truediv__ like Python 3. http://docs.python.org/reference/datamodel.html#emulating-numeric-types Cheers, Ian
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