d57caed52c
which can be reviewed via http://coding.derkeiler.com/Archive/Python/comp.lang.python/2003-12/1011.html Duncan Booth investigated, and discovered that an "optimisation" was in fact a pessimisation for small numbers of elements in a source list, compared to not having the optimisation, although with large numbers of elements in the source list the optimisation was quite beneficial. He posted his change to comp.lang.python (but not to SF). Further research has confirmed his assessment that the optimisation only becomes a net win when the source list has more than 100 elements. I also found that the optimisation could apply to tuples as well, but the gains only arrive with source tuples larger than about 320 elements and are nowhere near as significant as the gains with lists, (~95% gain @ 10000 elements for lists, ~20% gain @ 10000 elements for tuples) so I haven't proceeded with this. The code as it was applied the optimisation to list subclasses as well, and this also appears to be a net loss for all reasonable sized sources (~80-100% for up to 100 elements, ~20% for more than 500 elements; I tested up to 10000 elements). Duncan also suggested special casing empty lists, which I've extended to all empty sequences. On the basis that list_fill() is only ever called with a list for the result argument, testing for the source being the destination has now happens before testing source types. |
||
|---|---|---|
| .. | ||
| RPM | ||
| ACKS | ||
| AIX-NOTES | ||
| BeOS-NOTES | ||
| BeOS-setup.py | ||
| HISTORY | ||
| NEWS | ||
| NEWS.help | ||
| PURIFY.README | ||
| Porting | ||
| README | ||
| RFD | ||
| SpecialBuilds.txt | ||
| cheatsheet | ||
| find_recursionlimit.py | ||
| gdbinit | ||
| indent.pro | ||
| pymemcompat.h | ||
| python-mode.el | ||
| python.man | ||
| setuid-prog.c | ||
| vgrindefs | ||
README
Python Misc subdirectory ======================== This directory contains files that wouldn't fit in elsewhere. Some documents are only of historic importance. Files found here ---------------- ACKS Acknowledgements AIX-NOTES Notes for building Python on AIX BeOS-NOTES Notes for building on BeOS BeOS-setup.py setup.py replacement for BeOS, see BeOS-NOTES cheatsheet Quick summary of Python by Ken Manheimer find_recursionlimit.py Script to find a value for sys.maxrecursionlimit gdbinit Handy stuff to put in your .gdbinit file, if you use gdb HISTORY News from previous releases -- oldest last HPUX-NOTES Notes about dynamic loading under HP-UX indent.pro GNU indent profile approximating my C style NEWS News for this release (for some meaning of "this") Porting Mini-FAQ on porting to new platforms PURIFY.README Information for Purify users pymemcompat.h Memory interface compatibility file. python.man UNIX man page for the python interpreter python-mode.el Emacs mode for editing Python programs README The file you're reading now RFD Request For Discussion about a Python newsgroup RPM (Old) tools to build RPMs SpecialBuilds.txt Describes extra symbols you can set for debug builds setuid-prog.c C helper program for set-uid Python scripts vgrindefs Python configuration for vgrind (a generic pretty printer)