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From: Mark H Weaver <mhw@netris.org>
To: ludo@gnu.org (Ludovic Courtès)
Cc: guile-devel@gnu.org
Subject: Re: The empty string and other empty strings
Date: Tue, 10 Jan 2012 07:27:00 -0500	[thread overview]
Message-ID: <8739bnagkr.fsf@netris.org> (raw)
In-Reply-To: <874nw353a4.fsf_-_@gnu.org> ("Ludovic \=\?utf-8\?Q\?Court\=C3\=A8s\?\= \=\?utf-8\?Q\?\=22's\?\= message of "Tue, 10 Jan 2012 10:13:07 +0100")

ludo@gnu.org (Ludovic Courtès) writes:
> Anyway, it seems that before, you couldn’t get any encoding error for
> scm_from_stringn ("", "SOME-ENCODING"), whereas now you can.

Good point.  I just committed a change to avoid this.

> A related question: can we have both narrow and wide empty strings?

I see one place where a wide null string could be created: vm-i-loader.c
line 115, within the "load-wide-string" vm instruction, calls
`scm_i_make_wide_string' but never calls `scm_i_try_narrow_string' as is
usually done.  I guess this might be because "load-wide-string" is
normally never used for strings that contain only Latin 1 characters.

Other than that, I don't see how a wide null string could exist outside
of temporaries, although it's hard to entirely rule out the possibility.
All of the code paths try to avoid using wide strings unless a wide
character is actually present.

If a wide null string did exist, I don't see what harm it would cause,
besides causing failure if `scm_i_string_chars' applied to it.

    Thanks,
      Mark



  parent reply	other threads:[~2012-01-10 12:27 UTC|newest]

Thread overview: 117+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-01-03  4:08 What's wrong with this? Bruce Korb
2012-01-03 15:03 ` Mike Gran
2012-01-03 16:26   ` Guile: " Bruce Korb
2012-01-03 16:30     ` Mike Gran
2012-01-03 22:24     ` Ludovic Courtès
2012-01-03 23:15       ` Bruce Korb
2012-01-03 23:33         ` Ludovic Courtès
2012-01-04  0:55           ` Bruce Korb
2012-01-04  3:12             ` Noah Lavine
2012-01-04 17:37               ` bytevector -- was: " Bruce Korb
2012-01-04 21:17             ` Ludovic Courtès
2012-01-04 22:36               ` Bruce Korb
2012-01-05  0:01                 ` Ludovic Courtès
2012-01-05 18:36                   ` non-reproduction of initial issue -- was: " Bruce Korb
2012-01-05 18:50                     ` Mark H Weaver
2012-01-04 12:19         ` Ian Price
2012-01-04 17:16           ` Bruce Korb
2012-01-04 17:21             ` Andy Wingo
2012-01-04 17:39             ` David Kastrup
2012-01-04 21:52             ` Ian Price
2012-01-04 22:18               ` Bruce Korb
2012-01-04 23:22                 ` Mike Gran
2012-01-04 23:59                 ` Mark H Weaver
2012-01-05 17:22                   ` Bruce Korb
2012-01-05 18:13                     ` Mark H Weaver
2012-01-05 19:02                       ` Mark H Weaver
2012-01-05 20:24                     ` David Kastrup
2012-01-05 22:42                     ` Mark H Weaver
2012-01-06  1:02                       ` Mike Gran
2012-01-06  1:41                         ` Mark H Weaver
2012-01-06  2:38                           ` Noah Lavine
2012-01-06 13:37                           ` Mike Gran
2012-01-06 14:11                             ` David Kastrup
2012-01-06 18:13                             ` Mark H Weaver
2012-01-06 19:06                               ` Bruce Korb
2012-01-06 19:19                                 ` David Kastrup
2012-01-06 20:03                                   ` Mark H Weaver
2012-01-07 16:13                                 ` Mark H Weaver
2012-01-07 17:35                                   ` mutable interfaces - was: " Bruce Korb
2012-01-07 17:47                                     ` David Kastrup
2012-01-07 18:30                                     ` Mark H Weaver
2012-01-07 18:55                                       ` Mark H Weaver
2012-01-06 22:23                               ` Guile BUG: " Bruce Korb
2012-01-06 23:11                                 ` Mark H Weaver
2012-01-06 23:35                                   ` Andy Wingo
2012-01-06 23:41                                   ` Bruce Korb
2012-01-07 15:00                                     ` Mark H Weaver
2012-01-07 15:27                                       ` Bruce Korb
2012-01-07 16:38                                         ` Mark H Weaver
2012-01-07 17:39                                           ` Bruce Korb
2012-01-09 15:41                                             ` Mark H Weaver
2012-01-09 17:27                                               ` Bruce Korb
2012-01-09 18:32                                                 ` Andy Wingo
2012-01-09 19:48                                                   ` Bruce Korb
2012-01-07 15:47                                       ` David Kastrup
2012-01-07 17:07                                         ` Mark H Weaver
2012-01-07 14:35                                   ` Mark H Weaver
2012-01-07 15:20                                     ` Mike Gran
2012-01-07 22:25                                     ` Ludovic Courtès
2012-01-10  9:13                                     ` The empty string and other empty strings Ludovic Courtès
2012-01-10 11:28                                       ` Mike Gran
2012-01-10 13:03                                         ` Mark H Weaver
2012-01-10 13:09                                           ` Mike Gran
2012-01-10 15:41                                           ` Mark H Weaver
2012-01-10 15:48                                             ` David Kastrup
2012-01-10 16:15                                               ` Mark H Weaver
2012-01-12 22:33                                                 ` Ludovic Courtès
2012-01-13  9:27                                                   ` David Kastrup
2012-01-13 16:39                                                     ` Mark H Weaver
2012-01-13 17:36                                                       ` David Kastrup
2012-01-16  8:26                                                       ` Marijn
2012-01-16  8:47                                                         ` David Kastrup
2012-01-20 21:31                                                       ` Andy Wingo
2012-01-10 14:10                                         ` David Kastrup
2012-01-10 12:21                                       ` Mike Gran
2012-01-10 12:27                                       ` Mark H Weaver [this message]
2012-01-10 16:34                                         ` Ludovic Courtès
2012-01-10 17:04                                           ` David Kastrup
2012-01-06 23:28                                 ` Guile BUG: What's wrong with this? Bruce Korb
2012-01-07 20:57                           ` Guile: " Ian Price
2012-01-08  5:05                             ` Mark H Weaver
2012-01-06  9:23                         ` David Kastrup
2012-01-05  7:22                 ` David Kastrup
2012-01-04 22:46             ` Ludovic Courtès
2012-01-04  3:04       ` Mike Gran
2012-01-04  9:35         ` nalaginrut
2012-01-04  9:41         ` David Kastrup
2012-01-04 21:07         ` Ludovic Courtès
2012-01-04 10:03     ` Mark H Weaver
2012-01-04 14:29       ` Mike Gran
2012-01-04 14:45         ` David Kastrup
2012-01-04 16:47         ` Andy Wingo
2012-01-04 17:14           ` David Kastrup
2012-01-04 17:32             ` Andy Wingo
2012-01-04 17:49               ` David Kastrup
2012-01-04 18:09                 ` Andy Wingo
2012-01-04 17:30           ` Bruce Korb
2012-01-04 17:44             ` David Kastrup
2012-01-04 18:26             ` Ian Price
2012-01-04 18:48               ` Mark H Weaver
2012-01-04 19:29               ` Bruce Korb
2012-01-04 20:20                 ` David Kastrup
2012-01-04 23:19                 ` Mark H Weaver
2012-01-04 23:28                   ` Bruce Korb
2012-01-07 15:43                   ` Fixed string corruption bugs (was Guile: What's wrong with this?) Mark H Weaver
2012-01-07 16:19                     ` Fixed string corruption bugs Andy Wingo
2012-01-04 18:31           ` Guile: What's wrong with this? Mark H Weaver
2012-01-04 18:43             ` Andy Wingo
2012-01-04 19:29               ` Mark H Weaver
2012-01-04 19:43                 ` Andy Wingo
2012-01-04 20:08                   ` Bruce Korb
2012-01-04 20:14                     ` David Kastrup
2012-01-04 20:56                     ` Andy Wingo
2012-01-04 21:30                       ` Bruce Korb
2012-01-04 17:19         ` Mark H Weaver
2012-01-05  4:24           ` Mark H Weaver
2012-01-04 22:37       ` Ludovic Courtès

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