[Python-Dev] PEP 461 - Adding % and {} formatting to bytes (original) (raw)

Mark Lawrence breamoreboy at yahoo.co.uk
Wed Jan 15 17:33:18 CET 2014

On 14/01/2014 19:56, Ethan Furman wrote:

Duh. Here's the text, as well. ;)

%s, because it is the most general, has the most convoluted resolution: - input type is bytes? pass it straight through - input type is numeric? use its xxx [1] [2] method and ascii-encode it (strictly) - input type is something else? use its bytes method; if there isn't one, raise an exception [3] Examples: >>> b'%s' % b'abc' b'abc' >>> b'%s' % 3.14 b'3.14' >>> b'%s' % 'hello world!' Traceback (most recent call last): ... TypeError: 'hello world' has no bytes method, perhaps you need to encode it?

For completeness I believe %r and %a should be included here as well. FTR %a appears to have been introduced in 3.2, but I couldn't find anything in the What's New and there's no note in the docs http://docs.python.org/3/library/stdtypes.html#printf-style-string-formatting to indicate when it first came into play.

-- My fellow Pythonistas, ask not what our language can do for you, ask what you can do for our language.

Mark Lawrence

More information about the Python-Dev mailing list