On Mon, Jan 25, 2010 at 7:32 PM, Michael Foord <fuzzy...@voidspace.org.uk> wrote: > On 26/01/2010 00:28, Christian Heimes wrote: >> >> Michael Foord wrote: >> >>> >>> How great is the complication? Making list.pop(0) efficient sounds like >>> a worthy goal, particularly given that the reason you don't use it is >>> because you *know* it is inefficient (so the fact that you don't use it >>> isn't evidence that it isn't wanted - merely evidence that you had to >>> work around the known inefficiency). >>> >> >> The implementation must be changed in at least four places: >> >> * The PyListObject struct gets an additional pointer that stores a >> reference to the head. I would keep the head (element 0) of the list in >> **ob_item and the reference to the malloc()ed array in a new pointer >> *ob_allocated. >> >> * PyList_New() stores the pointer to the allocated memory in >> op->ob_allocated and sets op->ob_item = op->ob_allocated >> >> * listpop() moves the op->ob_item pointer by one for the special case >> of pop(0) >> >> * list_resize() should occasionally compact the free space before the >> head with memcpy() if it gets too large. >> >> listinsert() could be optimized for 0 if the list has some free space in >> front of the header, too. >> >> I favor this approach over an integer offset because doesn't change the >> semantic of ob_item. >> >> Christian >> > > Well, on the face of it this doesn't sound like a huge increase in > complexity. Not that I'm qualified to judge. > > Michael > > -- > http://www.ironpythoninaction.com/ > http://www.voidspace.org.uk/blog > > READ CAREFULLY. By accepting and reading this email you agree, on behalf of > your employer, to release me from all obligations and waivers arising from > any and all NON-NEGOTIATED agreements, licenses, terms-of-service, > shrinkwrap, clickwrap, browsewrap, confidentiality, non-disclosure, > non-compete and acceptable use policies (”BOGUS AGREEMENTS”) that I have > entered into with your employer, its partners, licensors, agents and > assigns, in perpetuity, without prejudice to my ongoing rights and > privileges. You further represent that you have the authority to release me > from any BOGUS AGREEMENTS on behalf of your employer. > > > _______________________________________________ > Python-Dev mailing list > Python-Dev@python.org > http://mail.python.org/mailman/listinfo/python-dev > Unsubscribe: > http://mail.python.org/mailman/options/python-dev/alex.gaynor%40gmail.com >
Does anyone know if any other language's automatic array (or whatever they call it) special case the pop(0) case like this? Alex -- "I disapprove of what you say, but I will defend to the death your right to say it." -- Voltaire "The people's good is the highest law." -- Cicero "Code can always be simpler than you think, but never as simple as you want" -- Me _______________________________________________ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
