[Octave-bug-tracker] [bug #30419] set/get vs setappdata/getappdata for custom properties

[David Bateman]

Follow-up Comment #1, bug #30419 (project octave):

Why can't we have Octave style properties added to the base properties and
setappdata/getappdata properties as well. For example with the functions

function setappdata (h, name, val)
   addproperty (name, h, "any", val);
endfunction

function x = isappdata (h, name)
  x = any (strcmp (name, fieldnames (getappdata (h))));
endfunction

function rmappdata (h, name)
   ## FIXME Need to write this function in graphics.cc
   delproperty (h, name);
endfunction

and then add the code

DEFUN (getappdata, args, , "there's no help for the wicked")
{
  int nargin = args.length ();
  octave_value retval;

  if (nargin != 1 || nargin != 2)
    print_usage ();
  else
    {
      double h = args(0).double_value ();

      if (! error_state)
        {
          graphics_handle gh = gh_manager::lookup (h);

          if (gh.ok ())
            {
              graphics_object go = gh_manager::get_object (gh);


              if (nargin == 1)
                retval = go.get_properties ().get_dynamic ();
              else
                {
                  std::string name = args(1).string_value ();

                  if (! error_state)
                    retval = go.get_properties ().get_dynamic (name);
                }
            }
        }
    }
}

to src/graphics.cc. In this manner you could keep the old behavior and be
compatible with matlab. If you want to get fancy you could do it all in
graphics.cc, or at least the isappdata function as this could be more
efficient as a DEFUN in graphics.cc.

For the fact the the appdata of the axes holds the data for the matlab line
color, style and the hold style, this is undocumented and we shouldn't rely on
it and don't need to implement it in the same fashion. Unless you're telling
me its common knowledge and many people in the matlab world rely on this
behavior..

As for the COM versions of addproperty, I say tough luck.

D. 


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