[Python-Dev] PEP 460 reboot

Glenn Linderman v+python at g.nevcal.com
Mon Jan 13 22:29:08 CET 2014

On 1/13/2014 12:09 PM, Guido van Rossum wrote:
> Yeah, the %s behavior with a string argument was a messy attempt at
> compromise. I was hoping to mimick a common use of %s in Python 2,
> where it can be used with either an 8-bit string or a number as
> argument, acting like %b in the former case and like %d in the latter
> case. Not having %s at all in Python 3 means that porting requires
> more thinking (== more opportunity for mistakes when you're converting
> in bulk) and there's no easy way to write code that works in Python 2
> and 3.
> If we have %b for strictly interpolating bytes, I'm fine with adding
> %a for calling ascii() on the argument and then interpolating the
> result after ASCII-encoding it.
> If somehow (unlikely though it seems) we end up keeping %s (e.g.
> strictly to ease porting), we could also keep %r as an alias for %a.

%s for strictly interpolating bytes eases porting. Sad name, but good 
for compatibility. When the blowup happens, due to having a str type 
passed, the porter adds the appropriate .encode(...) to the parameter, 
so it doesn't blow up on Py 3, and it'll be OK for Py 2 as well, will it 
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.python.org/pipermail/python-dev/attachments/20140113/237add2f/attachment-0001.html>

More information about the Python-Dev mailing list