[Python-Dev] RFC: PEP 460: Add bytes % args and bytes.format(args) to Python 3.5

[Antoine Pitrou]

On Tue, 7 Jan 2014 00:54:17 +1100
Chris Angelico <rosuav at gmail.com> wrote:
> On Tue, Jan 7, 2014 at 12:44 AM, Antoine Pitrou <solipsis at pitrou.net> wrote:
> > BTW, there's a subtlety here: ``%s`` currently means "insert the result
> > of calling __str__", but bytes formatting should *not* call __str__.
> 
> Since it derives from the C printf notation, it means "insert string
> here". The fact that __str__ will be called is secondary to that. I
> would say it's not a problem for bytes formatting to call __bytes__,
> or in some other way convert to bytes without calling __str__.
> 
> Will it be confusing to have bytes and str supporting distinctly
> different format operations? Might it be better to instead create a
> separate and very different method on a bytes, just to emphasize the
> difference?

The people who want bytes formatting, AFAICT, want something that is
reasonably 2.x-compatible. That means using the same method / operator
and calling conventions.

Regards

Antoine.