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Groups > comp.lang.python > #99815
| From | Denis McMahon <denismfmcmahon@gmail.com> |
|---|---|
| Newsgroups | comp.lang.python |
| Subject | Re: Could you explain this rebinding (or some other action) on "nums = nums"? |
| Date | 2015-12-01 20:32 +0000 |
| Organization | A noiseless patient Spider |
| Message-ID | <n3l050$l7a$4@dont-email.me> (permalink) |
| References | <94c2e42e-1e5f-40cf-9259-26035e277bf3@googlegroups.com> <mailman.37.1435191416.3674.python-list@python.org> <b48d4b38-a28a-4408-8271-f79e850f453f@googlegroups.com> <mailman.51.1448940760.14615.python-list@python.org> |
On Tue, 01 Dec 2015 03:32:31 +0000, MRAB wrote: > In the case of: > > tup[1] += [6, 7] > > what it's trying to do is: > > tup[1] = tup[1].__iadd__([6, 7]) > > tup[1] refers to a list, and the __iadd__ method _does_ mutate it, but > then Python tries to put the result that the method returns into tup[1]. > That fails because tup itself is a tuple, which is immutable. I think I might have found a bug: $ python Python 2.7.3 (default, Jun 22 2015, 19:33:41) [GCC 4.6.3] on linux2 Type "help", "copyright", "credits" or "license" for more information. >>> tup = [1,2,3],[4,5,6] >>> tup ([1, 2, 3], [4, 5, 6]) >>> tup[1] [4, 5, 6] >>> tup[1] += [7,8,9] Traceback (most recent call last): File "<stdin>", line 1, in <module> TypeError: 'tuple' object does not support item assignment >>> tup[1] [4, 5, 6, 7, 8, 9] >>> tup ([1, 2, 3], [4, 5, 6, 7, 8, 9]) >>> quit() -- Denis McMahon, denismfmcmahon@gmail.com
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Re: Could you explain this rebinding (or some other action) on "nums = nums"? fl <rxjwg98@gmail.com> - 2015-11-30 18:14 -0800
Re: Could you explain this rebinding (or some other action) on "nums = nums"? MRAB <python@mrabarnett.plus.com> - 2015-12-01 03:32 +0000
Re: Could you explain this rebinding (or some other action) on "nums = nums"? Denis McMahon <denismfmcmahon@gmail.com> - 2015-12-01 20:32 +0000
Re: Could you explain this rebinding (or some other action) on "nums = nums"? Ian Kelly <ian.g.kelly@gmail.com> - 2015-12-01 14:44 -0600
Re: Could you explain this rebinding (or some other action) on "nums = nums"? Denis McMahon <denismfmcmahon@gmail.com> - 2015-12-01 21:37 +0000
Re: Could you explain this rebinding (or some other action) on "nums = nums"? Erik <python@lucidity.plus.com> - 2015-12-01 22:34 +0000
Re: Could you explain this rebinding (or some other action) on "nums = nums"? Erik <python@lucidity.plus.com> - 2015-12-01 22:44 +0000
Re: Could you explain this rebinding (or some other action) on "nums = nums"? Terry Reedy <tjreedy@udel.edu> - 2015-12-01 16:18 -0500
Re: Could you explain this rebinding (or some other action) on "nums = nums"? Denis McMahon <denismfmcmahon@gmail.com> - 2015-12-01 21:36 +0000
Re: Could you explain this rebinding (or some other action) on "nums = nums"? Terry Reedy <tjreedy@udel.edu> - 2015-12-01 17:37 -0500
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