[Python-Dev] PEP 461: Adding % formatting to bytes and bytearray -- Final, Take 2

Victor Stinner victor.stinner at gmail.com
Sun Feb 23 22:56:27 CET 2014

>> (You forgot "/Uhhhhhhhh" representation (it's an antislah, but I don't
>> see the key on my Mac keyboard?).)
> Hard to forget what you don't know.  ;)  Will ascii() ever emit an
> antislash representation?

Try ascii(chr(0x1fffff)).

 What is the use case of this *new* formatter? How do you use it?
> An aid to debugging -- need to see what's what at that moment?  Toss it
> into %a.  It is not intended for production code, but is included to
> hopefully circumvent the inappropriate use of __bytes__ methods on classes.

How do you plan to use this output? Write it into a socket or a file?

When I debug, I use print & logging which both expect text string. So I
think that b'%a' is useless.

>  print(b'%a" % 123) may emit a BytesWarning and may lead to bugs.
> Why would it emit a BytesWarning?

Because print expects a text string, and print(bytes) does an implicit
conversion to Unicode. Try: python -bb -c "print(b'hello')".

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