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

[Brett Cannon]

On Mon, Jan 6, 2014 at 8:44 AM, Antoine Pitrou <solipsis at pitrou.net> wrote:

>
> Hi,
>
> On Mon, 6 Jan 2014 14:24:50 +0100
> Victor Stinner <victor.stinner at gmail.com> wrote:
> >
> > The PEP is a draft with open questions. First, I'm not sure that both
> > bytes%args and bytes.format(args) are needed. The implementation of
> > .format() is more complex, so why not only adding bytes%args?
>
> I think we must either implement both or none of them.
>

Or bytes.format() only. But I do agree that only implementing the %
operator is the wrong answer.

-Brett


>
> > Then,
> > the following points must be decided to define the complete list of
> > supported features (formatters):
> >
> > * Format integer to hexadecimal? ``%x`` and ``%X``
> > * Format integer to octal? ``%o``
> > * Format integer to binary? ``{!b}``
> > * Alignment?
> > * Truncating? Truncate or raise an error?
>
> Not desirable IMHO. bytes formatting should serve mainly for templating
> situations (i.e. catenate and insert bytestrings into one another). We
> cannot start giving text-like semantics to bytes objects without
> confusing non-experts.
>
> > * format keywords? ``b'{arg}'.format(arg=5)``
> > * ``str % dict`` ? ``b'%(arg)s' % {'arg': 5)``
>
> Yes, bytes formatting must support the same calling conventions as str
> formatting.
>
> BTW, there's a subtlety here: ``%s`` currently means "insert the result
> of calling __str__", but bytes formatting should *not* call __str__.
>
> > * Floating point number?
> > * ``%i``, ``%u`` and ``%d`` formats for integer numbers?
> > * Signed number? ``%+i`` and ``%-i``
>
> No, IMHO.
>
> Regards
>
> Antoine.
>
>
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