Re: non-interactive usage and color error messages

[Petr M. <mi...@ph...>]

> > It is neither nice or useful when gnuplot is writing error message such as:
> > 
> > Error: terminal "dumb" does not support continuous colors.
> > This terminal does not support palette-based images.
> > This terminal does not support rgb images.
> > This terminal does not support filled polygons.
> > 
> > when in non-interactive mode (e.g. driven via Octave). They are actually 
> > just warnings, not errors.
>
> Every message that is generated by 
>   fprintf(stderr,ERROR_NOTICE(foo))
> should be changed to use int_warn() instead.

Good idea. These ERROR_NOTICEs are actually warnings only, not errors. I've 
tried to patch this replacement in color.c and graphics.c, it works fine.

Constructions with ERROR_NOTICE are found also in gplt_x11.c. It seems to me 
that they serve for reporting problems with ipc communication, so they 
should "never" happen. The int_warn() construct cannot be used in gplt_x11.

The (interactive) mode is off also for the load command, where the messages 
can be useful.


Well, I came to this problem when testing the "dumb" terminal from within 
Octave (ssh without x11). Then every plot was entitled 
    Error: terminal "dumb" does not support continuous colors.
I want to get rid of that annoying message in this terminal - the dumb 
terminal is too dumb for this message :-)

Thus I propose to add
  if (strcmp(term->name,"dumb"))
before these warnings in graphics.c:
  int_warn "terminal ... does not support continuous colors.",term->name;
  int_warn "terminal ... does not support palette-based images.",term->name;
  int_warn "terminal ... does not support rgb images.",term->name;

Further, there is:
  int_error(NO_CARET, "This terminal does not support filled polygons");
I think that this should be changed to
  int_warn "terminal ... does not support filled polygons.",term->name;
with the same if ("dumb").

All other screen/interactive terminals implement all of these functions so 
the message never appears for them.

> Or maybe we could add a command line option
>    gnuplot -nowarnings
> and/or an internal command
>    unset warnings

Yes, this may be interesting. There are indeed languages where you can set 
warnings on and off.

---
PM