New submission from Karthikeyan Singaravelan <tir.kar...@gmail.com>:
There was a change made in collections.Counter that made it accept self as the first parameter and hence while doing *args in the method signature args[0] is always set as the self. Hence the check for `not args` becomes a no-op during collection_object.update() calls and the type error is not raised. This is only triggered when it's called as a class method like `Counter.update` and the error message is misleading "descriptor 'update' of 'Counter' object "needs an argument" which says update method of Counter object needs an argument though we are calling the method on class and also calling update on Counter object doesn't need an argument since counter_object.update() works fine as no-op. I think the error message could be improved since argument is not necessary for counter_object.update. Relevant commit : https://github.com/python/cpython/commit/ae5cb214d2cd41d96943a0ef43a4e95bd9a10b7a#diff-f30cb98704c3ccaf71deaf5503f7f4a1R587 No argument to counter object update test case : https://github.com/python/cpython/blob/ae5cb214d2cd41d96943a0ef43a4e95bd9a10b7a/Lib/test/test_collections.py#L1077 Calling update on Counter class test case : https://github.com/python/cpython/commit/20994f1e27c38973f1854dbdcf9b29fe8e3cd6be#diff-b5f669eab2fa576572b6115caa24427fR928 # Python 3 ➜ cpython git:(master) ✗ ./python Python 3.8.0a0 (heads/bpo33830-httplib-docs-fix-dirty:9bf0fb8, Jun 18 2018, 17:09:54) [GCC 5.4.0 20160609] on linux Type "help", "copyright", "credits" or "license" for more information. >>> from collections import Counter >>> c = Counter("Hello") >>> Counter.update() Traceback (most recent call last): File "<stdin>", line 1, in <module> File "/user/karthik/cpython/Lib/collections/__init__.py", line 638, in update raise TypeError("descriptor 'update' of 'Counter' object " TypeError: descriptor 'update' of 'Counter' object needs an argument >>> Counter.update(1) # No error since we check for the first argument to be >>> iterable >>> c.update() # No args works fine though there was an above error with >>> TypeError: descriptor 'update' of 'Counter' object needs an argument when >>> called on class >>> Counter.update(1, foo=1) # 1 is considered as self here, a valid counter >>> object works fine and is updated Traceback (most recent call last): File "<stdin>", line 1, in <module> File "/user/karthik/cpython/Lib/collections/__init__.py", line 655, in update self.update(kwds) AttributeError: 'int' object has no attribute 'update' Thanks ---------- components: Library (Lib) messages: 319935 nosy: xtreak priority: normal severity: normal status: open title: collections.counter update method without argument gives misleading error versions: Python 3.8 _______________________________________ Python tracker <rep...@bugs.python.org> <https://bugs.python.org/issue33900> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
