[Pkg-octave-devel] Bug#675509: still problems with Emacs inferior-octave mode iwth 3.8.0

[Francesco Potortì]

>When Octave is running in the Emacs inferior mode, it is given the
>--no-line-editing option. Therefore, I believe that this is the same
>underlying cause. And that means that fltk cannot work within Emacs
>currently.

In fact, calling octave -qf --no-line-editing from an X terminal
exhibits the same problem.  Nice that you have found the cause :)

>I think there are two possible ways forward. This can be discussed with
>the Emacs maintainers to see if that option can be removed. 

I doubt it.  I'd bet that the octave-inferior mode is based on comint,
which manages the line editing itself.  This is for simplicity and for
consistency with the Emacs environment.  In fact, I set gnuplot as the
plotting engin in my .octaverc and I keep regularly using Octave under
Emacs.

>							     If Octave
>does run readline, does it fatally break the inferior mode interface to
>Emacs, or is it just doing extra work and the mode authors thought they
>would be saving some overhead?

The Emacs interface should be completely rewritten for inferior-octave
to avoid using comint.  This is not impossible, but I think it is a
significant work.  Obviously, there may be people that have an excellent
grasp on Emacs lisp that want to do the job, so don't just take my word
for it.

>Another way is to simply prevent the fltk toolkit from being selected as
>the active toolkit when readline is disabled in Octave. This is already
>done when DISPLAY is unset, for example. Gnuplot would be used as a
>fallback.

This should definitely be done, and only removed the moment Octave is
made to work with fltk even while using --no-line-editing.
Additionally, when using --no-line-editing, attempts to change the
graphics engine to fltk should elicit a warning or something like that.

>Of course, if you or anyone else can show a case where this fltk problem
>still happens without the --no-line-editing option and outside of Emacs
>mode, then there may still be an undiagnosed problem with fltk.

Will remember that :)

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