Re: Is it save to dig into comment contents of PropList.txt?

From: Karl Williamson <>
Date: Wed, 06 Nov 2013 10:11:06 -0700

On 11/06/2013 03:43 AM, Steffen Daode Nurpmeso wrote:
> Philippe Verdy <> wrote:
> |2013/11/5 Steffen Daode <>
> |> (The problem i'm facing is that _PRINT and _GRAPH cannot be set
> |> for some properties from PropList.txt, say, _PRINT can't be set
> |> for U+0009, CHARACTER TABULATION (ht), since it's a Cc, but in
> |
> |TAB is "printable" (for the isprint() macro in standard C librries) because
> |it has a whitespace property, even if its general category is very weakly
> Nope according to POSIX, Vol. 1: Base Definitions, 7.3.1. LC_CTYPE ([1]):
> print
> Define characters to be classified as printable characters,
> including the <space>.
> In the POSIX locale, all characters in class graph shall be
> included; no characters in class cntrl shall be included.
> In a locale definition file, characters specified for the
> keywords upper, lower, alpha, digit, xdigit, punct, graph, and
> the <space> are automatically included in this class. No
> character specified for the keyword cntrl shall be specified.
> [1] <>
> Verifieable under LC_ALL=en_GB.UTF-8 in Mac OS X Snow Leopard
> (which admittedly uses very old Citrus data, i always wonder why all
> those Gigabytes of «Software Update»s don't tweak that, not to
> talk about GNU make 3.81 and all the other buggy or non-compliant
> stuff, but that is a different story):
> #include <stdio.h>
> #include <ctype.h>
> #include <wctype.h>
> int main(void) {
> printf("%d %d\n",isprint('\t'), wcwidth(L'\t'));
> return 0;
> }
> ?0[steffen_at_sherwood tmp]$ cc -o zt t.c && ./zt
> 0 -1
> |The character mapping for the isprint() macro is defined by an expression
> |based on existing Unicode properties. Most C libraries optimize this
> But i agree that POSIX has to move towards Unicode definitions,
> and more byte- than bitwise.
> --steffen

The only vendor I'm aware of that makes TAB a printable is Microsoft.
Thus Philippe is wrong about this except for MS products.

MS makes TAB also a control, violating the Posix standard by having it
be both printable and a control. This is true in all locales I've seen
under MS except the C locale. (MS also has other Posix violations, such
as having isdigit() match superscript numbers.)
Received on Wed Nov 06 2013 - 11:13:16 CST

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