[issue5864] format(1234.5, '.4') gives misleading result
Mark Dickinson dicki...@gmail.com added the comment: I'm not going to backport this to 2.6. The problem is that the fix for this issue is tied up with the corresponding change to str (str(1e11) produces '1e+11' in trunk and 1000.0 in release26-maint); I daren't change str() in 2.6, so backporting would mean separating out the str and format changes. I'm not opposed to the backport itself; it's just a lack of time and confidence of getting it right on my part. If anyone else wants to backport feel free. -- assignee: marketdickinson - ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue5864 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue5864] format(1234.5, '.4') gives misleading result
Mark Dickinson dicki...@gmail.com added the comment: ... and 3.0 is dead. -- versions: -Python 3.0 ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue5864 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue5864] format(1234.5, '.4') gives misleading result
Eric Smith e...@trueblade.com added the comment: I agree that backporting it to 2.6 would be nice, but it would be a huge change. There's too much risk involved. So this will just be a new feature in 2.7. It's already in Misc/NEWS, so you're all set there. I'm closing the issue, marking it as wont fix because it's only assigned to 2.6 currently. -- assignee: - marketdickinson resolution: - wont fix stage: patch review - committed/rejected status: open - closed ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue5864 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue5864] format(1234.5, '.4') gives misleading result
Mark Dickinson dicki...@gmail.com added the comment: Eric, any thoughts on whether this should be backported to 2.6 and 3.0? It looks like quite a lot of work. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue5864 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue5864] format(1234.5, '.4') gives misleading result
Changes by Mark Dickinson dicki...@gmail.com: -- priority: - normal versions: +Python 2.6, Python 3.0 -Python 2.7, Python 3.1 ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue5864 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue5864] format(1234.5, '.4') gives misleading result
Eric Smith e...@trueblade.com added the comment: I don't see any point in backporting to 3.0 at this point. While it's definitely a problem in 2.6, it seems like a big change to make in a bugfix release. I guess I'm +0 on it. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue5864 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue5864] format(1234.5, '.4') gives misleading result
Mark Dickinson dicki...@gmail.com added the comment: I'm working on a patch. The fix for the new-style PyOS_double_to_string using Gay's dtoa is a one-liner. The fix for the fallback code is going to take a little while longer... -- assignee: - marketdickinson ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue5864 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue5864] format(1234.5, '.4') gives misleading result
Mark Dickinson dicki...@gmail.com added the comment: Here's a patch for py3k; backporting to trunk should be straightforward. Backporting to 2.6 may involve more work. -- keywords: +patch Added file: http://bugs.python.org/file13813/issue5864.patch ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue5864 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue5864] format(1234.5, '.4') gives misleading result
Mark Dickinson dicki...@gmail.com added the comment: Updated patch; the previous patch messed str() up. -- Added file: http://bugs.python.org/file13814/issue5864.patch ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue5864 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue5864] format(1234.5, '.4') gives misleading result
Changes by Mark Dickinson dicki...@gmail.com: Removed file: http://bugs.python.org/file13813/issue5864.patch ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue5864 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue5864] format(1234.5, '.4') gives misleading result
Changes by Mark Dickinson dicki...@gmail.com: -- stage: needs patch - patch review ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue5864 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue5864] format(1234.5, '.4') gives misleading result
Eric Smith e...@trueblade.com added the comment: I'm getting an undefined _remove_trailing_zeros using a normal build (not using the fallback code). I think it's now always called. -- stage: patch review - needs patch ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue5864 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue5864] format(1234.5, '.4') gives misleading result
Mark Dickinson dicki...@gmail.com added the comment: I think it's now always called. I think you're right. I've moved remove_trailing_zeros further up, out of the #ifdef PY_NO_SHORT_FLOAT_REPR. -- Added file: http://bugs.python.org/file13816/issue5864_v2.patch ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue5864 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue5864] format(1234.5, '.4') gives misleading result
Eric Smith e...@trueblade.com added the comment: Using the _v2 patch, I tested both with the fallback code and with Gay's code, and both work. It's sort of shocking just how much effort you had to go through! But I can't see a simpler way to do it. It looks good to me. -- stage: needs patch - patch review ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue5864 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue5864] format(1234.5, '.4') gives misleading result
Mark Dickinson dicki...@gmail.com added the comment: Thanks, Eric. Applied to py3k in r72109. I've blocked it from release30- maint for now, since it will almost certainly not be possible to svnmerge it cleanly, but that doesn't preclude backporting it at some stage. I'll backport to trunk soon. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue5864 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue5864] format(1234.5, '.4') gives misleading result
Mark Dickinson dicki...@gmail.com added the comment: Backported to trunk in r72119. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue5864 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue5864] format(1234.5, '.4') gives misleading result
New submission from Mark Dickinson dicki...@gmail.com: In all versions of Python from 2.6 up, I get the following behaviour: format(123.456, '.4') '123.5' format(1234.56, '.4') '1235.0' format(12345.6, '.4') '1.235e+04' The first and third results are as I expect, but the second is somewhat misleading: it gives 5 significant digits when only 4 were requested, and moreover the last digit is incorrect. I propose that Python 2.7 and Python 3.1 be changed so that the output for the second line above is '1.235e+03'. Note that in both Python and C, '%.precisiong' formatting switches to exponential notation at 1eprecision precisely to avoid the problem of producing more significant digits than were requested; I'm proposing that the same solution be applied for '' formatting, except that since the empty format code is always required to produce at least one digit after the decimal point, the switch should happen at 1eprecision-1 instead of 1eprecision. This change should not be backported to 2.6 or 3.0 since there's a small risk of breakage (particular in doctests). -- components: Interpreter Core messages: 86728 nosy: eric.smith, marketdickinson severity: normal stage: needs patch status: open title: format(1234.5, '.4') gives misleading result type: behavior versions: Python 2.7, Python 3.1 ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue5864 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue5864] format(1234.5, '.4') gives misleading result
Eric Smith e...@trueblade.com added the comment: I agree this should be changed. This: format(1234.56, '.4') '1235.0' is definitely a problem. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue5864 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue5864] format(1234.5, '.4') gives misleading result
Raymond Hettinger rhettin...@users.sourceforge.net added the comment: I think the change should be deemed a bug and backported. Nothing good can come from having version differences persist or from having the odd looking output. -- nosy: +rhettinger ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue5864 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
