[Python-Dev] %x formatting of floats - behaviour change since 3.4

[Eric V. Smith]

On 6/3/2014 5:38 PM, Chris Angelico wrote:
> I'm helping out with the micropython project and am finding that one
> of their tests fails on CPython 3.5 (fresh build from Mercurial this
> morning). It comes down to this:
> 
> Python 3.4.1rc1 (default, May  5 2014, 14:28:34)
> [GCC 4.8.2] on linux
> Type "help", "copyright", "credits" or "license" for more information.
>>>> "%x"%16.0
> '10'
> 
> Python 3.5.0a0 (default:88814d1f8c32, Jun  4 2014, 07:29:32)
> [GCC 4.7.2] on linux
> Type "help", "copyright", "credits" or "license" for more information.
>>>> "%x"%16.0
> Traceback (most recent call last):
>   File "<stdin>", line 1, in <module>
> TypeError: %x format: an integer is required, not float
> 
> Is this an intentional change? And if so, is it formally documented
> somewhere? I don't recall seeing anything about it, but my
> recollection doesn't mean much.

http://bugs.python.org/issue19995