[Maxima-bugs] [maxima:bugs] #4569 reset(plot_options) doesn't reset plot_options

[Jaime E. V. <vi...@us...>]

plot_options (a Maxima list) is not used by the plotting progams (plot2d, plot3d, julia, ...).
The plotting options used by those programs are in a Lisp "property list" that can only be accessed in Maxima with the functions get_plot_option() and set_plot_option().
See the following example (after commit [b05e4e]):
~~~
(%i1) plot_options;
(%o1)                 [[plot_format, gnuplot_pipes]]
(%i2) get_plot_option();
(%o2) [[plot_format, gnuplot_pipes], [grid, 30, 30], [run_viewer, true], 
[axes, true], [nticks, 29], [adapt_depth, 5], 
[color, blue, red, green, magenta, black, cyan], 
[point_type, bullet, box, triangle, plus, times, asterisk], 
[palette, [hue, 0.33333333, 0.7, 1, 0.5], [hue, 0.8, 0.7, 1, 0.4]], 
[gnuplot_svg_background, white], [gnuplot_preamble, ], 
[gnuplot_term, default]]
(%i3) set_plot_option([plot_format,xmaxima])$
(%i4) reset(plot_options)$
(%i5) plot_options;
(%o5)                 [[plot_format, gnuplot_pipes]]
(%i6) get_plot_option();
(%o6) [[plot_format, xmaxima], [grid, 30, 30], [run_viewer, true], 
[axes, true], [nticks, 29], [adapt_depth, 5], 
[color, blue, red, green, magenta, black, cyan], 
[point_type, bullet, box, triangle, plus, times, asterisk], 
[palette, [hue, 0.33333333, 0.7, 1, 0.5], [hue, 0.8, 0.7, 1, 0.4]], 
[gnuplot_svg_background, white], [gnuplot_preamble, ], 
[gnuplot_term, default]]
~~~
As explained in the source code (src/plot.lisp), The plotting options are now in a Lisp list \*plot-options\* which should not be changed directly from Maxima, but using set_plot_option(), to avoid wrong options or wrong values.
When that Lisp list was introduced, Andrej Vodopivek complaint that Wxmaxima required a non-empty plot_options variable, so I introduced plot_options (Maxima list) with the minimum content of "[plot_format,gnuplot_pipes]". I don't know if newer versions of Wxmaxima still use plot_options (Maxima list).
What I will do is to introduce a reset_plot_options() function and figure out a way to prevent users from changing the Maxima list plot_options.



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**[bugs:#4569] reset(plot_options) doesn't reset plot_options**

**Status:** closed
**Group:** None
**Created:** Tue Jun 17, 2025 02:26 PM UTC by Raymond Toy
**Last Updated:** Tue Jun 17, 2025 11:28 PM UTC
**Owner:** Raymond Toy


Here's an example:
```
(%i1) plot_options;
(%o1)                   [[plot_format, gnuplot_pipes]]
(%i2) plot_options:junk;
(%o2)                                junk
(%i3) plot_options;
(%o3)                                junk
(%i4) reset(plot_options);
(%o4)                                 []
(%i5) plot_options;
(%o5)                                junk
```
I think `reset(plot_options)` should reset the value.

Maxima doesn't because it's defined using a `defvar` and it's not in the `*variable-initial-values*` hash table. This could be fixed by using `defmvar` to define the variable.  


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