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| References | (1 earlier) <jbqil6$esn$1@dough.gmane.org> <mailman.3417.1323357938.27778.python-list@python.org> <18647617.2258.1323358966076.JavaMail.geo-discussion-forums@yqf20> <mailman.3421.1323359453.27778.python-list@python.org> <3164448.1087.1323369765528.JavaMail.geo-discussion-forums@yqcm37> |
|---|---|
| Date | 2011-12-08 13:57 -0500 |
| Subject | Re: Misleading error message of the day |
| From | Benjamin Kaplan <benjamin.kaplan@case.edu> |
| Newsgroups | comp.lang.python |
| Message-ID | <mailman.3443.1323370719.27778.python-list@python.org> (permalink) |
On Thu, Dec 8, 2011 at 1:42 PM, Roy Smith <roy@panix.com> wrote: > (some, > very, > long, > list, > of, > variable, > names, > to, > get, > the, > stuff, > unpacked, > into) = function_that_should_return_a_14_tuple() > > raises > > ValueError: too many values to unpack > > Quick, what's the bug? Did I forget a variable on the LHS, or is my function returning more things than it should? I know it's supposed to be 14, but I don't know which side is wrong. Had it said "... expected 13, got 14", I would know immediately. > If the RHS was a tuple or a list, yes you could know immediately. But unpacking works with any iterable, so it probably doesn't special-case lists and tuples. Iterables don't have a size- they just keep going until StopIteration is raised. So in EVERY SINGLE CASE, you would get "expected n args, got n+1" even if the iterable would return 24 items instead of 14, or would never stop returning items. > Error messages should be as explicit as possible. It's just like bug reports. The basic mantra of a bug report is: > > 1) This is what I did > > 2) This is what I expected to happen > > 3) This is what I observed happen > > 4) This is how what I observed differed from what I expected > > Saying, "expected X, got Y" is more explicit than "got too many" > > > -- > http://mail.python.org/mailman/listinfo/python-list
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Misleading error message of the day Roy Smith <roy@panix.com> - 2011-12-08 09:23 -0500
Re: Misleading error message of the day Andrea Crotti <andrea.crotti.0@gmail.com> - 2011-12-08 14:39 +0000
Re: Misleading error message of the day Chris Angelico <rosuav@gmail.com> - 2011-12-09 01:40 +1100
Re: Misleading error message of the day Robert Kern <robert.kern@gmail.com> - 2011-12-08 14:47 +0000
Re: Misleading error message of the day Roy Smith <roy@panix.com> - 2011-12-08 07:30 -0800
Re: Misleading error message of the day Tim Chase <python.list@tim.thechases.com> - 2011-12-08 11:41 -0600
Re: Misleading error message of the day Roy Smith <roy@panix.com> - 2011-12-08 07:30 -0800
Re: Misleading error message of the day Jean-Michel Pichavant <jeanmichel@sequans.com> - 2011-12-08 16:03 +0100
Re: Misleading error message of the day Roy Smith <roy@panix.com> - 2011-12-08 07:33 -0800
Re: Misleading error message of the day Jean-Michel Pichavant <jeanmichel@sequans.com> - 2011-12-08 20:49 +0100
Re: Misleading error message of the day Ethan Furman <ethan@stoneleaf.us> - 2011-12-08 12:13 -0800
Re: Misleading error message of the day Lie Ryan <lie.1296@gmail.com> - 2011-12-09 12:46 +1100
Re: Misleading error message of the day alex23 <wuwei23@gmail.com> - 2011-12-08 20:57 -0800
Re: Misleading error message of the day Lie Ryan <lie.1296@gmail.com> - 2011-12-11 10:41 +1100
Re: Misleading error message of the day Jean-Michel Pichavant <jeanmichel@sequans.com> - 2011-12-09 11:03 +0100
Re: Misleading error message of the day Roy Smith <roy@panix.com> - 2011-12-09 09:43 -0500
Re: Misleading error message of the day Ethan Furman <ethan@stoneleaf.us> - 2011-12-09 09:39 -0800
Re: Misleading error message of the day Roy Smith <roy@panix.com> - 2011-12-08 07:33 -0800
Re: Misleading error message of the day Grant Edwards <invalid@invalid.invalid> - 2011-12-08 18:10 +0000
Re: Misleading error message of the day alister <alister.ware@ntlworld.com> - 2011-12-08 20:58 +0000
Re: Misleading error message of the day Chris Angelico <rosuav@gmail.com> - 2011-12-09 08:17 +1100
Re: Misleading error message of the day Roy Smith <roy@panix.com> - 2011-12-08 20:19 -0500
Re: Misleading error message of the day Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-12-09 02:07 +0000
Re: Misleading error message of the day Chris Angelico <rosuav@gmail.com> - 2011-12-09 14:46 +1100
Re: Misleading error message of the day Roy Smith <roy@panix.com> - 2011-12-08 23:44 -0500
Re: Misleading error message of the day Heiko Wundram <modelnine@modelnine.org> - 2011-12-08 16:16 +0100
Re: Misleading error message of the day Roy Smith <roy@panix.com> - 2011-12-08 07:42 -0800
Re: Misleading error message of the day Heiko Wundram <modelnine@modelnine.org> - 2011-12-08 16:50 +0100
Re: Misleading error message of the day Roy Smith <roy@panix.com> - 2011-12-08 10:42 -0800
Re: Misleading error message of the day Benjamin Kaplan <benjamin.kaplan@case.edu> - 2011-12-08 13:57 -0500
Re: Misleading error message of the day Ethan Furman <ethan@stoneleaf.us> - 2011-12-08 11:09 -0800
Re: Misleading error message of the day Benjamin Kaplan <benjamin.kaplan@case.edu> - 2011-12-08 14:38 -0500
Re: Misleading error message of the day Ethan Furman <ethan@stoneleaf.us> - 2011-12-08 12:09 -0800
Re: Misleading error message of the day Roy Smith <roy@panix.com> - 2011-12-08 10:42 -0800
Re: Misleading error message of the day Andrea Crotti <andrea.crotti.0@gmail.com> - 2011-12-08 15:55 +0000
Re: Misleading error message of the day Chris Angelico <rosuav@gmail.com> - 2011-12-09 03:21 +1100
Re: Misleading error message of the day Robert Kern <robert.kern@gmail.com> - 2011-12-08 19:57 +0000
Re: Misleading error message of the day Roy Smith <roy@panix.com> - 2011-12-08 07:42 -0800
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