[Python-Dev] Python 3.6 dict becomes compact and gets a private version; and keywords become ordered (original) (raw)
INADA Naoki songofacandy at gmail.com
Mon Sep 12 12:56:05 EDT 2016
- Previous message (by thread): [Python-Dev] Python 3.6 dict becomes compact and gets a private version; and keywords become ordered
- Next message (by thread): [Python-Dev] Python 3.6 dict becomes compact and gets a private version; and keywords become ordered
- Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]
On Tue, Sep 13, 2016 at 1:35 AM, Guido van Rossum <guido at python.org> wrote:
Couldn't we use the order in the actual hash table (which IIUC now contains just indexes into the ordered vector of key/value/hash structs)? That would probably simulate the pre-3.6 order quite effectively.
Maybe, it can. But current implementation may be faster on iteration, thanks to hardware prefetch of CPU. When sizeof(entry) is 24 (amd64), only 2.66... entries can be on cache line.
But we'd have to add a new API to reveal the order (in effect just what Nick wanted). How much of the OrderedDict can be implemented just by adding new methods (IOW without changing the data structure)?
Current data structure uses fixed capacity, mostly append only array for entries.
To implement OrderedDict.move_to_end(last=False), OrderedDict should be
implement more hack. (e.g. use the array as ring.)
- Previous message (by thread): [Python-Dev] Python 3.6 dict becomes compact and gets a private version; and keywords become ordered
- Next message (by thread): [Python-Dev] Python 3.6 dict becomes compact and gets a private version; and keywords become ordered
- Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]