On 25 February 2013 01:24, Chris Angelico <ros...@gmail.com> wrote: > On Mon, Feb 25, 2013 at 11:45 AM, Oscar Benjamin > <oscar.j.benja...@gmail.com> wrote: >> On 25 February 2013 00:08, <piterrr.dolin...@gmail.com> wrote: >> Chris Angelico wrote: >>>> For example (I believe it's already been mentioned) "declaring" intX with >>>> some integer value does *nothing* to maintain >>>> >>>> X as an integer: >>>> >>>> --> intX = 32 >>>> >>>> --> intX = intX / 3.0 >>>> >>>> --> intX >>>> >>>> 10.6666666666 >>>> >>> >>> Yes I did see that it is possible to redefine the type of a variable. But I >>> don't think I would ever do this intentionally; need to be really careful >>> with Python. > >> The trickier cases are ones where two types are very similar and can >> be used similarly in most, but not all, situations. An example of this >> would be the one that Chris has highlighted where an object that you >> expected to be an int is actually a float. I find that I need to be >> careful when using division on quantities that I expected to be >> integers (true in all languages) and careful about the notation used >> in a numeric literal. Once you get used to it, you will find it easy >> to see that the '.0' that Chris appended was deliberate in order to >> control the type of the resulting object. > > Once again, Ethan gets the short end of the citations stick... > 'twarn't me wrote that, he did. Not that it's at all contrary to my > views, and I might well have said it if he hadn't, but credit should > go his direction :)
Apologies to you both. The information was missing and I attempted to fill it in but got it wrong. > Note though that in Python 3, you don't need the explicit .0 to force > it to float (and __future__ can bring that to Python 2 too). 32/3 -> > 10.66666, int/int->float. That's true and I'm very glad of this change in Python 3. However other issues of float/int ambiguity remain for those (like me) who are particularly concerned with numbers and their accuracy/exactness. So it is still necessary in Python 3 to be careful around this issue. While it is an issue in all languages, it is one that is often easier to deal with in statically typed languages than in Python. Oscar -- http://mail.python.org/mailman/listinfo/python-list
