Why Python 3?

[Ian Kelly]

On Sat, Apr 19, 2014 at 2:31 PM, Chris Angelico <rosuav at gmail.com> wrote:
> On Sun, Apr 20, 2014 at 5:58 AM, Ian Kelly <ian.g.kelly at gmail.com> wrote:
>> Considering that Fraction and Decimal did not exist yet, what type do
>> you think the PEP 238 implementers should have chosen for the result
>> of dividing two ints?  If float is not acceptable, and int is not
>> acceptable (which was the whole point of the PEP), then the only
>> alternative I can see would have been to raise a TypeError and force
>> the user to upcast explicitly.  In that case, dividing arbitrary ints
>> using floating-point math would not be possible for those ints that
>> are outside the range of floats; you would get OverflowError on the
>> upcast operation, regardless of whether the result of division would
>> be within the range of a float.
>>
>>> Yes, I can see that it's nice for simple interactive use.
>>
>> More importantly, it's useful for implementers of generic mathematical
>> routines.  If you're passed arbitrary inputs, you don't have to check
>> the types of the values you were given and then branch if both of the
>> values you were about to divide happened to be ints just because the
>> division operator arbitrarily does something different on ints.
>
> Or you just cast one of them to float. That way you're sure you're
> working with floats.

Which is inappropriate if the type passed in was a Decimal or a complex.