Re: __gnuplot_set__ fails as function call 2.9.1

[John W. Eaton]

On  1-Apr-2005, Daniel J Sebald <address@hidden> wrote:

| Could you please clarify the big picture on this?  My understanding
| was that instead of having a plotting device at the core of Octave,
| it would be moved to the "__plot__", etc. m-scripts.  There there
| could be any plotting utility.  So what this would require is a
| unique set of m-scripts for, say, gnuplot commands.  In those
| scripts would be a way to launch gnuplot and do the things you
| mention above.
| 
| I assume there will be other types of graphics packages put together
| this way.

Yes, I think there already are.  The one in Octave based on gnuplot
was the only special one.

Other code that is not part of a specific graphics package should use
the high-level plotting functions, not the low-level things like
__gnuplot_raw__.  That way it can work with any graphics package.

Eventually, maybe we will converge on a single preferred package for
doing graphics from inside Octave.  But until then, we should try to
make it easy to experiment with different options.  If people need
additional features (line widths, etc.) then we should agree on how to
get that into the higher-level plotting functions.  It makes sense
for compatibility to provide a handle-graphics interface for that, but
that does not have to be the only way (in the past, we've discussed
things like

  h.property = value;

as an alternative to

  set (h, property, value, ...);

for setting graphics properties.

| But how then does someone indicate their selection of which plotting
| utility to use?  Is this something selected when installing?

I think it should be selectable at run-time, using LOADPATH.

| How does one close gnuplot if it is launched from a plotting m file?
| Is there to be some hook into Octave that can call a command upon
| exit, just like .octaverc?

Use closeplot.  The code to interface with gnuplot is still in C++.
Commands like __gnuplot__ (i.e., the current __gnuplot_raw__) would
include the necessary magic to automatically (re)start gnuplot if
needed and kill it when Octave exits.

jwe