New submission from Kristján Valur Jónsson <krist...@ccpgames.com>:
It is sometimes useful to be able to swap the contents of two lists and this patch provides a way to do so using the fastest way possible. > a = [1, 2] > b = [3] > id(a), id(b) (100, 101) > a.swap(b) > a [3] > b [1, 2] > id(a), id(b) (100, 101) One application of this is to make help a performance problem when one wants to upgrade a list instance into a subclass instance. orglist = rawlist_from_server() mylist = ListSubclass(orglist) This involves copying duplicating the list, and then discarding, which can take a while for long lists. Much faster is using> mylist = ListSubclass() mulist.swap(orglist) We are using this extension within CCP to decoratate database queries from our database engine, that are returned as python lists. The performance gained by shaving off this extra list duplication can be significant for large data sets. to change a list, into a ---------- components: Interpreter Core files: listswap.patch keywords: patch, patch messages: 89626 nosy: krisvale severity: normal status: open title: Add a "swap" method to list type: feature request versions: Python 2.7 Added file: http://bugs.python.org/file14341/listswap.patch _______________________________________ Python tracker <rep...@bugs.python.org> <http://bugs.python.org/issue6326> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
