New submission from Juan Carlos Pujol Mainegra: Let s be a string or other array-like object, a, b > 0 integers, s[0:b] returns a b-long prefix to s, the same as s[:b], but s[-a:0] returns empty (for len(s) > 0 and a > 1), while it should return the same as s[-a:], an a-long suffix (a > 0).
A syntax asymmetry like this shall not be imposed to those using non-literal slicing indexes, as it would be necessarily to introduce a control condition to test whether the upper bound index is a non-negative quantity, assuming the lower bound index is negative. Furthermore, it breaks the whole negative slicing idea, being that (I consider) index i always be treated as i mod len(s), so that constructions like s[-a:b] (for a, b > 0 or a, b < 0) could return s[-a:] + s[:b]. ---------- components: Interpreter Core messages: 277829 nosy: jksware priority: normal severity: normal status: open title: Slicing (operation) is not symmetrical with respect to suffixes and prefixes type: enhancement versions: Python 3.6 _______________________________________ Python tracker <rep...@bugs.python.org> <http://bugs.python.org/issue28336> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
