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

Antoine Pitrou solipsis at pitrou.net
Mon Jan 6 14:44:52 CET 2014

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.

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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