Alexander Belopolsky added the comment: > Is this change compelling enough to break compatibility, > or is it just a matter of purity?
According to the PEP 3141, Integer is a subtype of Real, so one should be able to substitute an Integer whenever Real is expected. The reverse is not true, for example >>> [1,2][1.0] Traceback (most recent call last): File "<stdin>", line 1, in <module> TypeError: list indices must be integers, not float This is one of the common uses of floor division - to find an index of a cell in a regular grid: (x - start) // step. In this situation, it is convenient to have the result ready to be used as an index without a cast. The substitution principle also suggests that compatibility issues are likely to be small: in most contexts integers behave the same as floats or "better". Here is an example of a "better" behavior: >>> x = 1 + 10**50 >>> x * 1 == x True >>> x * 1.0 == x False The only case I can think of where float result may be preferable is inf // 1 because integers cannot represent infinity. However, this case is arguably already broken. What are the use-cases for float // float where integer result is not acceptable? ---------- _______________________________________ Python tracker <rep...@bugs.python.org> <http://bugs.python.org/issue22444> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
