Re: Question: How does ncurses store and handle "wide" characters?

[Bill Gray]

On 6/3/21 7:49 PM, Thomas Dickey wrote:

> Looking at the 3.4 headers (on Linux...),

   That's going back a ways,  but it's the same in the current 3.9
(and in PDCursesMod).  In each case,  there's only one curses.h,
used for all platforms (DOS, OS/2, Windows, Plan9,  etc.)

> PDCurses has this:
>
>      XCURSES         True if compiling for X11.
>      PDC_RGB         True if you want to use RGB color definitions
>                      (Red = 1, Green = 2, Blue = 4) instead of BGR.
>      PDC_WIDE        True if building wide-character support.
>      PDC_DLL_BUILD   True if building a Win32 DLL.
>      NCURSES_MOUSE_VERSION   Use the ncurses mouse API instead
>                              of PDCurses' traditional mouse API.
>
> but the "XCURSES" is misplaced (it should be set by the implementation,
> and PDC_DLL_BUILD is irrelevant on Linux).

   That list ought to also include (and this would apply to 3.4,  too)

       PDC_FORCE_UTF8   Force use of UTF8 instead of locale

   It does look as if XCURSES is a hangover no longer serving much
of a purpose on PDCurses/PDCursesMod.  We should probably rename it
to something like ENABLE_X11_FUNCS... except that would break some
existing systems.  As you say,  it's hard to drop things that others
might be using.

> The others are set by the user.
>
> In ncurses, there's no summary of set-by-the-user.  ncurses' curses.h is
> more than twice as long as that for PDcurses, with 3-4 times as many "#if"
> lines.  But most of that is for constants (settings done in the configure
> script). Offhand, there's about as many symbols that the user might
> define -- which might be better expressed in the manpage, since a one-line
> comment doesn't help that much, to explain why a feature is compile-time
> configurable.
>
> Looking quickly, I see
>
>         NCURSES_ATTR_T (normally not set by users)
>         NCURSES_INTERNALS (normally not set by users)
>         NCURSES_WATTR_MACROS
>         NCURSES_REENTRANT
>         NCURSES_WIDECHAR
>         NCURSES_NOMACROS
>
> Most of the other symbols are set by the configuration scripts.
>
> (I'm reminded that I should get rid of "TRACE", which is very old,
> e.g., replacing it with "NCURSES_TRACE",
> but can't simply drop things that others might be using...)
>
> Following up on the bit-layout, though: I use the symbols all the time,
> and don't look at the hex/octal values of the mouse-masks or attributes.
>
> >     I'm a little lost here.  I gather you're thinking the
> > wide-character support in PDCurses is enabled by default?
> > It isn't;  you have to compile with PDC_WIDE enabled.  Omit
> > that,  and only eight of the 21 character bits actually
> > get used.  Or are you seeing some other deviation?
> >
> > Thanks!    -- Bill