[Python-ideas] Stop displaying elements of bytes objects as printable ASCII characters in CPython 3

[Wolfgang Maier]

On 09/10/2014 12:57 PM, Steven D'Aprano wrote:
> On Wed, Sep 10, 2014 at 12:04:23AM -0700, Chris Lasher wrote:
>
> [...]
>> I would like to gauge the feasibility of a PEP to change the printable
>> representation of bytes in CPython 3 to display all elements by their
>> hexadecimal values, and only by their hexadecimal values.
>
> I'm very sympathetic to this "purity" approach. I too consider it a
> shame that the repr of byte-strings in Python 3 pretends to be
> ASCII-ish[1], regardless of the source of the bytes. Alas, not only do
> we have backward compatibility to consider -- there are now five versions
> of Python 3 where bytes display as ASCII -- but practicality as well.
> There are many use-cases where human-readable ASCII bytes are embedded
> inside otherwise binary bytes. To my regret, I don't think purity
> arguments are strong enough to justify a change.
>
> However, I do support Terry's suggestion that bytes (and, I presume,
> bytearray) grow some sort of easy way of displaying the bytes in hex.
> The trouble is, what do we actually want?
>
> b'Abc' --> '0x416263'
> b'Abc' --> '\x41\x62\x63'
>
> I can see use-cases for both. After less than two minutes of thought, it
> seems to me that perhaps the most obvious APIs for these two different
> representations are:
>
> hex(b'Abc') --> '0x416263'

This would require a change in the documented 
(https://docs.python.org/3/library/functions.html#hex) behavior of 
hex(), which I think is quite a big deal for a relatively special case.

> b'Abc'.decode('hexescapes') --> '\x41\x62\x63'

This, OTOH, looks elegant (avoids a new method) and clear (no doubt 
about the returned type) to me.
+1

Wolfgang