[Octave-bug-tracker] [bug #35662] Using default arguments for axis properties causes error

[Rik]

Update of bug #35662 (project octave):

                 Summary: set ticklength breaks plot => Using default
arguments for axis properties causes error

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Follow-up Comment #3:

Actually, this is a general problem with all the update_XXX functions which
don't just set a variable but call other update_XXX functions.  I'm going to
re-title the bug to reflect that.

Here is another example


set (0, 'defaultaxesxlim', [-1 2])
gca
error: __go_axes__: operator *: nonconformant arguments (op1 is 0x0, op2 is
4x1)


The issue is that when the axis is being constructed it overrides the defaults
by calling set_XXX with the new default.  This function call is done before
any other axis setup has been done and so the set_XXX functions which rely on
having an existing axis fail.

One obvious solution would be to build the axis, and then set all the
defaults.  This would obviously have a lot of redundancy as an axis was set up
with multiple properties which then needed to be changed.

A second idea would be to code some signaling variable, such as building_axes,
which updating functions would check before calling the update function.

For example, Here is the code for the set_ticklength function


  void set_ticklength (const octave_value& val)
  {
    if (! error_state)
      {
        if (ticklength.set (val, true))
          {
            update_ticklength ();
            mark_modified ();
          }
      }
  }


And here it is with the proposed change


  void set_ticklength (const octave_value& val)
  {
    if (! error_state)
      {
        if (ticklength.set (val, true) && ! building_axes)
          {
            update_ticklength ();
            mark_modified ();
          }
      }
  }



It's still a hack, but right now Octave is broken for several properties that
one can set defaults on.


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