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

[Antoine Pitrou]

On Fri, 10 Jan 2014 05:26:04 +1000
Nick Coghlan <ncoghlan at gmail.com> wrote:
> 
> We should probably include format_map for consistency with the str API.

Yes, you're right.

> >However, I
> > also added bytearray into the mix, as bytearray objects should
> > generally support the same operations as bytes (and they can be useful
> > *especially* for network programming).
> 
> So we'd define the *format* string as mutable to get a mutable result out
> of the formatting operations? This seems a little weird to me.
> 
> It also seems weird for a format method on a mutable type to *not* perform
> in-place mutation.

It's consistent with bytearray.join's behaviour:

>>> x = bytearray()
>>> x.join([b"abc"])
bytearray(b'abc')
>>> x
bytearray(b'')


Regards

Antoine.