[Python-3000] Implementing % formatting in terms of str.format()

[Eric Smith]

Guido van Rossum wrote:
> I think there are too many risks with this approach, especially given
> that we're keeping % formatting mainly for backwards compatibility
> reasons. There will inevitably be corner cases where the conversion
> doesn't work exactly the same way as the old code or where the
> conversion is wrong for whatever reason, and it would be quite painful
> to change back.
> 
> If 2.6 can't support %b, so be it.

It would really be easiest to just say that if you want binary 
formatting in both 2.6 and 3.0, use str.format.  I don't think expanding 
the functionality of % formatting is what anyone should be spending 
their time on.

I'd be happy to update the PEP to drop %b.