New submission from Benjamin Peterson <benja...@python.org>: This patch completely rewrites errors given for positional error mismatches. The goal is to give more informative and correct errors.
Some examples: >>> def f(): pass ... >>> f(1) Traceback (most recent call last): File "<stdin>", line 1, in <module> TypeError: f() takes 0 positional arguments but 1 was given >>> f(1, kw=4) Traceback (most recent call last): File "<stdin>", line 1, in <module> TypeError: f() got an unexpected keyword argument 'kw' >>> def f(a, b=2): pass ... >>> f() Traceback (most recent call last): File "<stdin>", line 1, in <module> TypeError: f() takes from 1 to 2 positional arguments but 0 were given >>> f(1, 2, 3) Traceback (most recent call last): File "<stdin>", line 1, in <module> TypeError: f() takes from 1 to 2 positional arguments but 3 were given >>> def f(a, *b): pass ... >>> f() Traceback (most recent call last): File "<stdin>", line 1, in <module> TypeError: f() takes at least 1 positional argument but 0 were given >>> f(kw=4) Traceback (most recent call last): File "<stdin>", line 1, in <module> TypeError: f() got an unexpected keyword argument 'kw' When keyword-only arguments come into play, things get a bit more complicated. When a positional argument error occurs, it's confusing to report only the positional arguments, but not completely relevant to report keyword-only arguments. I comprise by putting the keyword-only argument information in parenthesis. Tell me if you have a better idea. >>> def f(*, kw): pass ... >>> f() Traceback (most recent call last): File "<stdin>", line 1, in <module> TypeError: f() requires keyword-only argument 'kw' >>> f(1) Traceback (most recent call last): File "<stdin>", line 1, in <module> TypeError: f() takes 0 positional arguments but 1 was given >>> f(3, kw=4) Traceback (most recent call last): File "<stdin>", line 1, in <module> TypeError: f() takes 0 positional arguments but 1 positional arguments (and 1 keyword-only argument) were given ---------- components: Interpreter Core files: argerror.patch keywords: patch messages: 137676 nosy: benjamin.peterson priority: normal severity: normal stage: patch review status: open title: revamp argument errors type: feature request versions: Python 3.3 Added file: http://bugs.python.org/file22252/argerror.patch _______________________________________ Python tracker <rep...@bugs.python.org> <http://bugs.python.org/issue12265> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
