From: Wojciech Meyer <wojciech.meyer@googlemail.com>
To: emacs-devel@gnu.org
Subject: Re: Pushing the `gnus-range-*' functions down into the C layer
Date: Sat, 11 Sep 2010 17:15:00 +0100 [thread overview]
Message-ID: <87y6b8tfy3.fsf@gmail.com> (raw)
In-Reply-To: <m3fwxgxoqz.fsf@quimbies.gnus.org> (Lars Magne Ingebrigtsen's message of "Sat, 11 Sep 2010 17:51:16 +0200")
Lars Magne Ingebrigtsen <larsi@gnus.org> writes:
> "Stephen J. Turnbull" <stephen@xemacs.org> writes:
>
>> No, for all types. First you have to check whether something is a
>> bignum, then if not you do a bit-pattern comparison. Worst case this
>> could double the cost of doing EQ(x,y) in C, and in Lisp `eq' will
>> cost a perceptible amount more.
>
> Right. Is EQ in C just implemented as a memory check, and absolutely
> nothing else? It doesn't touch the data at all in any way?
>
> *etag around a bit*
>
> #define EQ(x, y) (XHASH (x) == XHASH (y))
>
> which is
>
> /* Return a perfect hash of the Lisp_Object representation. */
> #define XHASH(a) (a)
>
> So, yeah, stupid idea. Never mind.
Yes, because it is physical equivalence, and pointers are unique. In
this case I agree, it should not be called XHASH because that implies it
is used for structural equivalence, which is misleading. Also, hashing
object should behave like deep copying - follow pointers.
Wojciech
next prev parent reply other threads:[~2010-09-11 16:15 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-09-09 15:16 Pushing the `gnus-range-*' functions down into the C layer Lars Magne Ingebrigtsen
2010-09-09 19:01 ` Ted Zlatanov
2010-09-09 21:58 ` Lars Magne Ingebrigtsen
2010-09-09 22:25 ` Ted Zlatanov
2010-09-10 3:24 ` Stephen J. Turnbull
2010-09-10 13:53 ` Ted Zlatanov
2010-09-10 14:01 ` Lars Magne Ingebrigtsen
2010-09-10 14:08 ` Leo
2010-09-10 14:15 ` Lars Magne Ingebrigtsen
2010-09-10 14:19 ` Wojciech Meyer
2010-09-11 9:44 ` Stefan Monnier
2010-09-10 14:18 ` Ted Zlatanov
2010-09-10 14:28 ` Lars Magne Ingebrigtsen
2010-09-10 14:38 ` bignums (was: Pushing the `gnus-range-*' functions down into the C layer) Ted Zlatanov
2010-09-10 15:16 ` Pushing the `gnus-range-*' functions down into the C layer Andreas Schwab
2010-09-10 15:22 ` David Kastrup
2010-09-10 15:26 ` Lars Magne Ingebrigtsen
2010-09-11 9:48 ` Stefan Monnier
2010-09-11 11:57 ` Lars Magne Ingebrigtsen
2010-09-11 15:36 ` Stephen J. Turnbull
2010-09-11 15:51 ` Lars Magne Ingebrigtsen
2010-09-11 16:15 ` Wojciech Meyer [this message]
2010-09-12 9:57 ` Stefan Monnier
2010-09-10 19:28 ` Tom Tromey
2010-09-14 15:52 ` Ted Zlatanov
2010-09-11 5:52 ` Stephen J. Turnbull
2010-09-13 11:45 ` Eli Zaretskii
2010-09-09 22:21 ` Wojciech Meyer
2010-09-09 23:48 ` Ted Zlatanov
2010-09-09 23:56 ` Wojciech Meyer
2010-09-10 0:07 ` Lars Magne Ingebrigtsen
2010-09-10 0:17 ` Wojciech Meyer
2010-09-10 8:06 ` Andy Wingo
2010-09-10 10:20 ` Wojciech Meyer
2010-09-10 10:43 ` Stefan Monnier
2010-09-10 12:35 ` Lars Magne Ingebrigtsen
2010-09-10 12:49 ` rfc2047-decode-string in C? Lars Magne Ingebrigtsen
2010-09-10 13:47 ` Stefan Monnier
2010-09-10 13:51 ` Lars Magne Ingebrigtsen
2010-09-11 16:10 ` Lars Magne Ingebrigtsen
2010-09-10 13:07 ` Pushing the `gnus-range-*' functions down into the C layer joakim
2010-09-10 13:22 ` Lars Magne Ingebrigtsen
2010-09-10 13:45 ` Stefan Monnier
2010-09-10 14:01 ` Ted Zlatanov
2010-09-10 14:09 ` Lars Magne Ingebrigtsen
2010-09-11 9:36 ` Stefan Monnier
2010-09-10 14:06 ` Lars Magne Ingebrigtsen
2010-09-11 3:18 ` Daniel Pittman
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