Re: [Bug-readline] Minor bone to pick regarding the doc for next_history()

[Chet Ramey]

On 3/24/15 10:50 AM, Glenn Golden wrote:
> From history.3, readline 6.3.006:
> 
>   HIST_ENTRY * next_history (void)
> 
>     Move the current history offset forward to the next history entry,
>     and return the a pointer to that entry.  If there is no next entry, 
>     return a NULL pointer.
> 
> This leaves unstated what happens to the value of 'offset' if there
> is "no next entry", and it seems there is no simple 'right' answer.
> 
> From experiments (via perl Term::ReadLine::Gnu) the actual behavior w.r.t
> the value of 'offset' after the call completes seems to be
> 
>     offset = (offset < history_length) ? offset+1 : offset;
> 
> which means that there are really two relevant forms of "no next entry" upon
> calling next_history():
> 
>   Case 1: offset == history_length-1
> 
>   Case 2: offset >  history_length-1

Yes, this is a good summary.  The last entry in the history list
(the_history[history_length]) is always NULL, or should be if you use
add_history to insert history entries.

I guess the shortest way to express the situation is something like
"if this function returns NULL, the history offset is at the end of
the history."

Chet
-- 
``The lyf so short, the craft so long to lerne.'' - Chaucer
                 ``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, ITS, CWRU    address@hidden    http://cnswww.cns.cwru.edu/~chet/