[pdp-discuss] TypeAccess question?

[Randall C. O'Reilly]

Ok, now I see the problem: you define an InitLinks() function with nothing in 
it.  InitLinks MUST call the parent class's initlinks (Layer::InitLinks()), 
and do any of its own functionality.  In your case, you don't need it, so 
remove it.  You are preventing the Layer Initlinks (and its parents) from 
operating...

In version 4.0, we have a TA_SIMPLE_BASEFUNS macro that does all this 
housekeeping stuff automatically :).  It should be available as a beta in a 
few weeks..

- Randy

On Wednesday 15 November 2006 09:02, Richard Jones wrote:
> 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.