Patches item #1629718, was opened at 2007-01-07 00:51 Message generated for change (Comment added) made by rhettinger You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=305470&aid=1629718&group_id=5470
Please note that this message will contain a full copy of the comment thread, including the initial issue submission, for this request, not just the latest update. Category: Core (C code) Group: Python 2.5 Status: Open Resolution: None Priority: 5 Private: No Submitted By: Hirokazu Yamamoto (ocean-city) Assigned to: Nobody/Anonymous (nobody) Summary: fast tuple[index] by inlining on BINARY_SUBSCR Initial Comment: Hello. I noticed there is speed difference between a = [0,] # list a[0] # fast and a = (0,) # tuple a[0] # slow while solving ICPC puzzle with Python. I thought this is wierd because, indeed tuple is readonly, there is no conceptual difference between list and tuple when 'extract' item from them. After investigation, I found this difference comes from the shortcut for list on ceval.c (BINARY_SUBSCR). Is it valuable to put shortcut for tuple too? I'll attach the patch for release-maint25 branch. Thank you. ---------------------------------------------------------------------- >Comment By: Raymond Hettinger (rhettinger) Date: 2007-01-07 22:56 Message: Logged In: YES user_id=80475 Originator: NO I recommend against this. Any additional specialization code will necessarily slow down other cases handled by PyObject_GetItem. So, the merits of speeding-up tuple indexing need to be weighed against the costs (slowing down other code and the excess loading of ceval.c with specialization code). Also, I reject the premise that there is no conceptual difference between list and tuple indexing. The former is a primary use case for lists and the latter is only incidental to tuple use cases (see the endless discussions on python-dev and comp.lang.python about why tuples are not to be regarded as immutable lists and in fact have a different intended set of uses). ---------------------------------------------------------------------- Comment By: Martin v. Löwis (loewis) Date: 2007-01-07 16:34 Message: Logged In: YES user_id=21627 Originator: NO It would be helpful to get some statistics on how often this occurs: of all case of BINARY_SUBSCR, how man refer to tuples, how many to lists, and how many to other objects? To get some data, you can measure a run of a test suite, or a run of IDLE, or of compileall. ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=305470&aid=1629718&group_id=5470 _______________________________________________ Patches mailing list Patches@python.org http://mail.python.org/mailman/listinfo/patches
