[New-bugs-announce] [issue20284] proof for concept patch for bytes formatting methods

Neil Schemenauer report at bugs.python.org
Thu Jan 16 22:33:09 CET 2014

New submission from Neil Schemenauer:

This is a very rough, proof of concept patch that implements %-style formatting for bytes objects.  Currently it calls __format__ with a bytes argument and expects a bytes result.  I've only implemented 
support for bytes formatting for the 'long' object.

Expected behavior:

>>> b'%s' % b'hello'
>>> b'%s' % 'hello'
TypeError is raised
>>> b'%s' % 123
>>> b'%d' % 123

Some issues:

- %s support is incomplete, needs to handle width and padding.  I think it should be done in formatbytes().

- PyBytes_Format function very likely has bugs, I copied it mostly from Python 2 and quickly made it run, I did very little testing.

- long__format__ with a bytes argument is inefficient.  It creates temporary Python objects that could be avoided.  %-style formatting on bytes will be much less efficient than str in Python 2.  We could inline the handling of certain types in PyBytes_Format, maybe longs only would be sufficent.

- I'm not sure overloading __format__ is the best approach.  Maybe we should introduce a new method, say __ascii__ instead and have PyBytes_Format call that.

components: Interpreter Core
files: bytes_mod.patch
keywords: patch
messages: 208313
nosy: nascheme
priority: normal
severity: normal
stage: patch review
status: open
title: proof for concept patch for bytes formatting methods
type: enhancement
versions: Python 3.5
Added file: http://bugs.python.org/file33501/bytes_mod.patch

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