| msg28186 - (view) |
Author: Marc-Andre Lemburg (lemburg) *  |
Date: 2006-04-10 19:39 |
| This looks like a bug in the way the %-formatting code works or is it a feature ? >>> '%s %(a)s' % {'a': 'xyz'} "{'a': 'xyz'} xyz" >>> u'%s %(a)s' % {'a': 'xyz'} u"{'a': 'xyz'} xyz" Note that both strings and Unicode are affected. Python 2.3 and 2.4 also show this behavior. I would have expected an exception or the %-formatter simply ignoring the first %s. |
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| msg28187 - (view) |
Author: Hasan Diwan (hdiwan650) |
Date: 2006-04-14 08:33 |
| Logged In: YES user_id=1185570 It looks as though it's a feature... The first %s will print the whole dictionary as a string, the second, only that value looked up by the key. |
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| msg28188 - (view) |
Author: Georg Brandl (georg.brandl) * |
Date: 2006-07-24 13:37 |
| Logged In: YES user_id=849994 The library ref specifies that if a dict is supplied, the format specifiers MUST include a mapping key, so the right thing to do would be to raise an exception. Is it worth breaking backwards compatibility, Martin? |
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| msg28189 - (view) |
Author: Martin v. Löwis (loewis) * |
Date: 2006-07-24 20:07 |
| Logged In: YES user_id=21627 IMO, it's correct to break backwards compatibility, as the current behaviour clearly violates the spec; I'm not sure whether it's good to break the behaviour *now* (i.e. with no further betas before the release of 2.5). Deferring to the release manager. |
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| msg28190 - (view) |
Author: A.M. Kuchling (akuchling) * |
Date: 2006-07-25 12:35 |
| Logged In: YES user_id=11375 So, what should '%s' % {} do? Should it be 1) '{}' or 2) an error because the argument is a mapping but the format specifier doesn't have a '(key)'? I've attached a draft patch that fixes stringobject.c; if the approach is deemed OK, I'll apply it to unicodeobject.c, too. PyString_Format() records the type of argument being processed (a tuple or a mapping) and raises ValueError if you mix them, at the cost of two extra comparisons for each format specifier processed. This preserves the current behaviour of '%s' % dictionary. Questions: 1) is the approach reasonably clear? 2) are the additional two comparisons unacceptably slow? 3) Is ValueError the right exception? 4) can someone come up with a better exception message than "both keyed and unkeyed format specifiers used"? |
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| msg28191 - (view) |
Author: Skip Montanaro (skip.montanaro) *  |
Date: 2006-08-04 13:21 |
| Logged In: YES user_id=44345 Looks okay to me, though why is the FORMAT_TYPE_UNKNOWN test necessary in the second case but not the first? |
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| msg28192 - (view) |
Author: Marc-Andre Lemburg (lemburg) * |
Date: 2006-08-04 13:26 |
| Logged In: YES user_id=38388 The patch looks OK. I'd make it a TypeError and use "cannot use positional and named formatting parameters at the same time" as message. Thanks. |
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| msg28193 - (view) |
Author: Jim Jewett (jimjjewett) |
Date: 2006-08-18 22:01 |
| Logged In: YES user_id=764593 Just a bit of encouragement for checking consistency like this; the explicit error message would have helped with a mistake I made earlier today. For one of several keys, I mistyped it as "(%key)s", and a message about "not enough values" just didn't make sense. |
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| msg28194 - (view) |
Author: Marc-Andre Lemburg (lemburg) * |
Date: 2006-08-18 22:17 |
| Logged In: YES user_id=38388 Should this patch be applied to the 2.5 branch ? And if so, before or after the release of 2.5 ? |
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| msg28195 - (view) |
Author: Georg Brandl (georg.brandl) * |
Date: 2006-08-19 05:25 |
| Logged In: YES user_id=849994 I'd say before 2.5 final... |
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| msg28196 - (view) |
Author: Anthony Baxter (anthonybaxter) |
Date: 2007-01-12 09:10 |
| I'm happy for this to be applied for 2.5.1. I don't have time to do it myself for a few days, though, so feel free to beat me to it. |
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| msg28197 - (view) |
Author: A.M. Kuchling (akuchling) * |
Date: 2007-01-12 14:57 |
| The patch shouldn't be applied as it stands, though, because it's not complete; similiar changes need to be made to the Unicode type, for a start. To answer Skip's question: I don't remember the logic of the format code. I think the FORMAT_TYPE_UNKNOWN check may be unnecessary; the code could just always do format_type = _TUPLE, occasionally doing a redundant assignment (but who cares)? I don't think I'll have any chance to work on this; PyCon is keeping me busy, and the mailbox bugs will take priority for me. |
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| msg55292 - (view) |
Author: Sean Reifschneider (jafo) * |
Date: 2007-08-25 20:15 |
| I'm attaching a new version of this which includes AMK's string patch ported over to unicode. Any objections to my committing this to the trunk? Should it also go in for the next 2.5 release? |
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| msg66798 - (view) |
Author: Georg Brandl (georg.brandl) * |
Date: 2008-05-13 19:27 |
| This probably won't be important anymore now that we have str.format()... |
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| msg66801 - (view) |
Author: Marc-Andre Lemburg (lemburg) * |
Date: 2008-05-13 20:06 |
| Sean, why don't you just check in the patch ? Then we can close the bug. Georg, the fact that we have an alternative method for string formatting doesn't mean that it's ok for Python to hide error using the prevailing method of string formatting. |
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| msg66802 - (view) |
Author: Georg Brandl (georg.brandl) * |
Date: 2008-05-13 20:42 |
| I didn't want to imply that, but seeing that nobody cared about it for so long I hadn't much hope for the future... ;) |
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| msg66813 - (view) |
Author: Marc-Andre Lemburg (lemburg) * |
Date: 2008-05-14 09:39 |
| I guess the patch was just forgotten after the 2.5 release was out. I've added a 2.6 tag and assigned the patch to Sean. |
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| msg86636 - (view) |
Author: Daniel Diniz (ajaksu2) * |
Date: 2009-04-27 01:19 |
| Confirmed in trunk and py3k. How about changing this for 3.1? |
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| msg86671 - (view) |
Author: Eric V. Smith (eric.smith) * |
Date: 2009-04-27 15:15 |
| The patch incorrectly raises an exception for: '%(a)s %%' % {'a':'xyz'} I'll look into fixing it. |
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| msg115960 - (view) |
Author: Florent Xicluna (flox) * |
Date: 2010-09-09 19:35 |
| Too late for 2.x and 3.1. |
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| msg119061 - (view) |
Author: Vetoshkin Nikita (nvetoshkin) |
Date: 2010-10-18 18:46 |
| Updated patch against py3k. Fixing last reported issue with '%(a)s %%' % {'a':'xyz'} |
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| msg119067 - (view) |
Author: Vetoshkin Nikita (nvetoshkin) |
Date: 2010-10-18 19:14 |
| Updated patch to capture another patological case: '%(a)s %' % {'a':'xyz'} - incomplete formatter at the end of the line |
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| msg119232 - (view) |
Author: Vetoshkin Nikita (nvetoshkin) |
Date: 2010-10-20 19:57 |
| Updated patch: some tests added. |
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| msg322586 - (view) |
Author: Tal Einat (taleinat) * |
Date: 2018-07-28 18:49 |
| Eric, would you like an update PR for this? |
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| msg322590 - (view) |
Author: Eric V. Smith (eric.smith) * |
Date: 2018-07-28 20:35 |
| I unassigned myself from this a few months ago. If someone wants to fix it, I'm not opposed. But the issue is 12 years old and doesn't cause any real problems as far as I can see, so it's hard to get excited about it. And as we've seen there are a lot of corner cases. I'd hate to make things worse. |
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| msg322613 - (view) |
Author: Tal Einat (taleinat) * |
Date: 2018-07-29 06:52 |
| Ah, sorry Eric, I misread that change as you assigning this to yourself. |
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| msg322650 - (view) |
Author: Raymond Hettinger (rhettinger) * |
Date: 2018-07-30 04:16 |
| [Eric V. Smith] > But the issue is 12 years old and doesn't cause any real problems > as far as I can see, so it's hard to get excited about it. > And as we've seen there are a lot of corner cases. I'd hate to > make things worse. I ooncur with Eric and think this ought to be closed. It is a oddity but has proven itself to be harmless in the wild. At this point in the life cycle of %-formatting it would be prudent to value stability over niggling behavior changes. |
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