[BoppreH]

I disagree. A strong type system is good, but in this case pragmatism wins the battle. I personally have been bitten innumerous times by bugs where division was rounded down (usually to 0, which is especially destructive).

Most of the numbers I encounter start as integers and most of the calculations I need are floating-point. This language behavior saves me from sprinkling "* 1.0" everywhere on my code, or from introducing extremely subtle bugs.

And the integer division is always there, one character away:

    print(1//2 * 1000)   # 0

[jimmaswell]

I just think it's nuts that we're upcasting ints to floats implicitly. Explicitness over implicitness is one of Python's guidelines.

[BoppreH]

Python3's '/' operator is different from Python2's '/' operator. This is clear when you try to overload them. Python2's is called '__div__', while Python3's is '__truediv__'.

The Python3's operator '/' (on numbers) is defined to return a float, and it'll convert any integer parameters as required. The same is true for other operators, like 'True + True' being 2.

Because of these definitions, you should consider the operators as explicit conversions. 'total / sum' is less explicit than 'total / float(sum)', but still clear enough.

And about guidelines, there are others that fit this case:

    Simple is better than complex.
    Flat is better than nested.
    Readability counts.
    [...] practicality beats purity.
    

PS: I think you made an important argument and I'm glad you did it, even though I disagree with it. I fail to see why you are getting downvotes.

[jimmaswell]

I guess I don't mind it that much.

I went to check out the operation and it seems a on two ints returns an int if the power is a nonnegative int, and a float if it's negative nonzero, in both 2.7 and 3. I didn't expect this kind of inconsistency from python, really.

    >>> type(2 ** 1)
    <type 'int'>
    >>> type(2 ** -1)
    <type 'float'>

I guess it does follow the last line of the guidelines there, though. Looking at this power example, the division returning float now is actually an increase in consistency.

[andreasvc]

I think it's better to think of it as division being an operation that returns the appropriate type for the operation, i.e., a float where necessary. The type of the operands remain unchanged so "upcasting" is not applicable if you ask me.