[Python-ideas] format specifier for "not bytes"

[MRAB]

On 25/08/2012 00:12, Daniel Holth wrote:
>
> On Aug 24, 2012 6:17 PM, "Paul Moore" <p.f.moore at gmail.com
> <mailto:p.f.moore at gmail.com>> wrote:
>  >
>  > On 24 August 2012 21:21, Daniel Holth <dholth at gmail.com
> <mailto:dholth at gmail.com>> wrote:
>  > > Hi Paul! You could probably guess that this is the wheel digital
>  > > signatures package. All the string formatting arguments (I hope) are
>  > > now passed to binary() or native() string conversion functions that do
>  > > less on Python 2.7 than on Python 3.
>  >
>  > One point that this raises. Any such "string-only" format spec would
>  > only be available in Python 3.4+, and almost certainly only in
>  > format(). So if you're interested in something that works across
>  > Python 2 and 3, you wouldn't be able to use it anyway (and something
>  > like the must_be_str function is probably your best bet). On the other
>  > hand, if you're targeting 3.4+ only, the bytes/string code is probably
>  > cleaner (that being a lot of the point of the Python 3 exercise :-))
>  > and so the need for a string-only spec may be a lot less.
>  >
>  > I dunno. I haven't hit a lot of encoding type issues myself, so I
>  > don't have much background in what might help. OTOH, what I *have*
>  > found is that the change in thinking that Python 3's approach pushes
>  > onto me (encode/decode at the edges and use str consistently
>  > internally, plus never gloss over the fact that you have to know an
>  > encoding to convert bytes <-> str) fixes a lot of "problems" I thought
>  > I was having...
>
> That's the core of it. You can convert bytes to string without knowing
> the encoding. "%s" % bytes. But instead of failing or converting from
> ascii it does something totally useless. I argue that this is a bug, and
> an alternative 'anything except bytes' should be available. Not so hot
> on the competing only-str idea.
>
"Totally useless"? Is it any more "useless" than what happens to lists,
dicts, sets, etc?