[Python-Dev] PEP 460 reboot (original) (raw)

Brett Cannon brett at python.org
Mon Jan 13 23:05:10 CET 2014

On Mon, Jan 13, 2014 at 4:51 PM, Guido van Rossum <guido at python.org> wrote:

Terminology. Let's use the official terminology rather than making stuff up.

The docs at http://docs.python.org/3/library/string.html#formatspec use the following terminology: Replacement field: {...}; contains field name, conversion, format spec in that order, all optional. Field name: either a decimal integer (referring to an argument by position) or an identifier (by name), or omitted (uses the next available position). Conversion: !r, !s, !a; these refer to repr(), str(), ascii() to the value, and then the format spec applies to the resulting string. Format spec: colon, bunch of stuff, type; the type is a letter such as d (decimal) or s (string), and the stuff between the colon and the type is used to specify field width, alignment, sign, padding and such.

Also. {:b} means binary (i.e. numbers in base 2). I'm not sure what this leaves for interpolating bytes if we don't want to use {:s}. The docs at http://docs.python.org/3/library/stdtypes.html#printf-style-string-formatting don't show %b so it could still be used there, but it would be nicer to be consistent.

I have been going on the assumption that bytes.format() would change what '{}' meant for itself and would only interpolate bytes. That convenient between Python 2 and 3 since it represents what we want it to (str and bytes under the hood, respectively), so it just falls through. We could also add a 'b' conversion for bytes() explicitly so as to help people not accidentally mix up things in bytes.format() and str.format(). But I was not suggesting adding a specific format spec for bytes but instead making bytes.format() just do the .encode('ascii') automatically to help with compatibility when a format spec was present. If people want fancy formatting for bytes they can always do it themselves before calling bytes.format(). -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://mail.python.org/pipermail/python-dev/attachments/20140113/ac52c725/attachment.html>

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