On Sat, Jan 21, 2017 at 10:15 AM, Thomas Nyberg <tomuxi...@gmx.com> wrote: > But I have one extra question. Is string indexing guaranteed to be > constant-time for python? I thought so, but I couldn't find it documented > anywhere. (Not that I think it practically matters, since it couldn't really > change if it weren't for all the reasons you mentioned.) I found this which > at details (if not explicitly "guarantees") the complexity properties of > other datatypes: >
No, it isn't; this question came up in the context of MicroPython, which chose to go UTF-8 internally instead of PEP 393. But the considerations for uPy are different - it's not designed to handle gobs of data, so constant-time vs linear isn't going to have as much impact. But in normal work, it's important enough to have predictable string performance. You can't afford to deploy a web application, test it, and then have someone send a large amount of data at it, causing massive O(n^2) blowouts. ChrisA -- https://mail.python.org/mailman/listinfo/python-list
