Reuben Thomas wrote:
> As far as I can see, there is an implementation of isblank in gnulib
> for systems that lack it, but I can't see how I'm supposed to use it:
> I can see the module c-ctypes which seems to be specifically for the C
> locale, and unictype/ctype-blank module, which mentions
> "generalisation", though it's not clear to me of what. What do I use
> if I just want to get the C99 "isblank" macro/function from ctype.h?
>
> Sorry if I'm being dense, but perhaps there's an opportunity for
> clarification here?
The relevant documentation in gnulib for this function is in the file
doc/posix-functions/isblank.texi:
"Gnulib module: ---
Portability problems fixed by Gnulib:
@itemize
@end itemize
Portability problems not fixed by Gnulib:
@itemize
@item
This function is missing on some platforms:
AIX 4.3.2, IRIX 6.5, OSF/1 5.1, Solaris 9, mingw.
@end itemize
"
This means that gnulib does not provide you a module that guarantees an
'isblank' function.
The reasons include:
1) No one asked for it so far.
2) On all known platforms, in all predefined locales, isblank(c) is likely
equivalent with (c == ' ' || c == '\t'). Look at the glibc definition
(in glibc/localedata/locales/i18n): The "blank" characters are
'\t', ' ', U+1680, U+180E, U+2000..U+2006, U+2008..U+200A, U+205F, U+3000,
and none except the two is present in a common 8-bit encoding.
So instead of using this function, with platform dependent semantics, most
programs will either want the pure ASCII version (c_isblank) or the Unicode
aware version (uc_is_blank).
Bruno
