Path: utzoo!attcan!uunet!dino!ux1.cso.uiuc.edu!mcs.anl.gov!midway!tank!stephen From: stephen@estragon.uchicago.edu (Stephen P Spackman) Newsgroups: comp.object Subject: Re: What is Objective C? Message-ID: Date: 5 Sep 90 23:44:04 GMT References: <3864@bingvaxu.cc.binghamton.edu> <2700002@hpspkla.spk.hp.com> <1990Sep4.034131.532@cbnewsl.att.com> <1990Sep5.013922.6739@cbnewsc.att.com> Sender: news@midway.uchicago.edu (News Administrator) Organization: University of Chicago CILS Lines: 30 In-Reply-To: lgm@cbnewsc.att.com's message of 5 Sep 90 01:39:22 GMT In article <1990Sep4.034131.532@cbnewsl.att.com>, psrc@cbnewsl.att.com (Paul S. R. Chisholm) writes: > So . . . will a program that, by the language definition, must do > garbage collection, run as quickly as a program where the "user" (the > programmer in the language in question) must manage memory? Probably > not, unless the language implementor has done a terrific job, and the > "user" has botched it. Will a program that, by the language > definition, must do an additional memory indirection, or even a table > look up at run time, run as quickly as a program where subroutine calls > can be translated straightforwardly into a subroutine call instruction? > Same answer. Perhaps the thing to note is that the language implementor is being paid to optimise that implementation, while the programmer is trying to produce a different product entirely. I don't know how these things usually go, but I once spent the better part of a year working on a garbage collector. So, in a sense, what you say is true: the fact that in my sixth month or so I made changes that improved performance EIGHTFOLD (interactions with paging algorithms improved by adapting generation-scanvenging techniques, reordering memory-visits, and avoiding dirtying pages) means that there WAS a lot of work to be done when I started. But on the other hand, a compiler writer can amortise six man-months spent tuning the garbage collector; chances are you can't. It's a bit like saying, why have a compiler when I can write assembly code? stephen p spackman stephen@estragon.uchicago.edu 312.702.3982