[pdp-discuss] TypeAccess question?

[Richard Jones]

Thanks for the reply.  Unfortunately, it doesn't help.  In the
TypeDef::GetValStr(...) I'm still getting an EXC_BAD_ACCESS on the
last of the following lines:

    ...
    if(DerivesFrom(TA_taBase)) {
      TAPtr rbase = *((TAPtr*)base);
      if((rbase != NULL) && ((rbase->GetOwner() != NULL) || (rbase ==
tabMisc::root))) {

One thing I did try, based on the first sentences of section 18.12 in
the help: "If a class contains a pointer to another object, it should
typically refer to that object whenever the pointer is set. The
interface assumes that this is the case, ..." was to put a dumb check
for equality to NULL right after setting my pointer to NULL in my
Initialize() function.  This seems to fix the problem but I don't see
why, and I haven't yet exhaustively verified this.

Does this seem like it should work?



On 11/14/06, Randall C. O'Reilly <Randy.OReilly at colorado.edu> wrote:
> I bet the SIMPLE_COPY doesn't handle the memberdef* case correctly -- try
> getting rid of that to see if that is the source of the problem.  if so,
> replace with:
>
> void Copy_(const TestLayer& cp) { var_md = cp.var_md; }
>
> - Randy
>
> On Tuesday 14 November 2006 18:58, Richard Jones wrote:
> > I've been having a recurring problem with my code.  Every now and then
> > I am getting core dumps while in executing in:
> >
> > String TypeDef::GetValStr(...)
> >
> > This will usually be when I want to open an edit dialog on a newly
> > created object, such as a layer.  It also happens if I try to save my
> > project after newly creating an object.  This latter is a disaster
> > since it writes out a corrupt proj.gz file and work is lost.   It
> > doesn't happen under all circumstances, but I've got it boiled down to
> > reproducibility.  Consider the following class:
> >
> >   class TestLayer : public Layer {
> >
> >   public:
> >
> >        MemberDef*     var_md;
> >
> >         void  UpdateAfterEdit() {};
> >         void  Initialize() { var_md = NULL;};
> >         void  Destroy()               { };
> >         void  InitLinks() {};
> >         SIMPLE_COPY(TestLayer);
> >         COPY_FUNS(TestLayer, Layer);
> >         TA_BASEFUNS(TestLayer);
> >   };
> >
> > If in NetViewer I create just one TestLayer and then try to edit it I
> > have no problem.  If I create two and try to edit the first, again no
> > problem.  But if I try to edit the second I get the dump.  Creating
> > one at a time doesn't seem to be a problem, most of the the time.
> >
> > The problem is related to my inclusion of pointers to taBase classes.
> > For instance, if I remove the "MemberDef* var_md" above the problem
> > goes away.   There must be something I'm supposed to do but am
> > missing.  Any advice I could get would be greatly welcome.
> >
> > Many thanks.
>


-- 
Richard Jones
dickjr at gmail.com