Re: reasoning behind default of 5 for CCHARW_MAX

[Nick Black]

Thomas Dickey left as an exercise for the reader:
> hmm - that dates from mid-1995 (first seen in 1.9.2d, undocumented),
> so it was added by either Eric or Zeyd.  They'd have copied from
> either a Dell SVr4 or AIX, respectively.
> 
> My impression was that one or more of the Unix vendors chose that limit.
> (I agree it seems excessive).  When Sven and I implemented wide-characters,
> we left it as is.
> 
> I have header files for several systems, and can investigate that
> to document it (as I did for A_COLOR).
> 
> AIX 4 used 5, for instance.  I don't have headers for the Dell SVr4,
> but have enough information to make a nice story.

Thanks as always for the insightful and thorough response,
Thomas. I've been looking into things this evening, and to cover
even basic Hindi it appears 3 are necessary. I'm not too
terribly worried about horrors like

"For example the sequence [U+1F468 U+200D U+1F469 U+200D U+1F467
 U+200D U+1F466] results in a composed emoji glyph for a "family:
 man, woman, girl, boy" on systems that support this kind of
 composition."

but losing one of the great cultures of the world is a bit much.
I think I might experiment with 3. Glad to hear that AIX thought
4 sufficient; that's promising.

Ideally (from a modern programmer's perspective) that array
would be wholly dynamic, I'd think. That complicates plenty of
drawing routines (and the data structures behind them) many
drawing routines, but it does seem possible within the
requirements of X/Open. I'd think it far too invasive a change
for far too little practical gain WRT ncurses, though.

"The internal storage format of characters and renditions is
 unspecified. There is no implied correspondence between the
 internal storage format and the external representation of
 characters and renditions in objects of type chtype and
 cchar_t."

I'll send a patch along with the suggested documentation change
and some others I've collected these past two weeks. Thanks!

-- 
nick black -=- https://www.nick-black.com
to make an apple pie from scratch,
you need first invent a universe.

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