Re: NSTabView Fix

[Wolfgang Lux]

Andreas Höschler wrote:

> > > > and we need to make sure these two match in some way. And what I  
> > > > tried to do was just this. If I failed on doing so, please show  
> > > > me my > wrongs.
> > >
> > > Create a tabView and add four tabViewItems. _selected_item will  
> > > be 4. Then call selectedTabViewItem! Boohm!!!
> >
> > So what? Fred's change looked okay to me (and still looks so). The  
> > point is
> > just that NSTabView fails to initialize the _selected_item  
> > instance variable
> > properly. Adding the line
> >   _selected_item = NSNotFound;
> > in -initWithFrame: should fix this issue.
>
> If NSNotFound is and will stay defined as -1 then YES! Can we build  
> on that?

No, because 0x7fffffff != -1 :-) (see NSObject.h; it's the same on  
Cocoa). Anyway
there is really no need to do so because the code (with two  
exceptions, see below)
carefully checks whether _selected_item is NSNotFound before  
incrementing or
decrementing the instance variable.

The two methods were the check is absent are -selectNextTabViewItem: and
-selectPreviousTabViewItem:. These methods might be changed as follows

  - (void) selectNextTabViewItem: (id)sender
  {
  #if 0
    /* the check below does work because 0x80000000 is cast to  
unsigned and thus
     * greater than the number of items; nevertheless, checking  
explicitly for
     * NSNotFound improves code clarity */
    if ((unsigned)(_selected_item + 1) < [_items count])
  #endif
    if (_selected_item != NSNotFound && (unsigned)(_selected_item +  
1) < [_items count]))
      [self selectTabViewItemAtIndex: _selected_item+1];
  }

  - (void) selectPreviousTabViewItem: (id)sender
  {
  #if 0
    /* the check below works just because even NSNotFound-1 is  
greater than the
       index of any item in the tab view and therefore  
selectTabViewItemAtIndex:
       will set the selected item (redundantly) to nil (and thereby  
also
       _selected_item to NSNotFound); nevertheless, checking  
explicitly for
       NSNotFound improves code clarity. */
    if (_selected_item > 0)
  #endif
    if (_selected_item != NSNotFound && _selected_item > 0)
      [self selectTabViewItemAtIndex: _selected_item-1];
  }


> Sorry (to Fred), I haven't looked for a fix for the fix yesterday.  
> I just discovered that the modification broke my code and therefore  
> rolled back to the older implementation. I suppose _selected_item =  
> -1; in the init method will do the trick.

No, it won't. You have to use _selected_item = NSNotFound or you are  
going to
break other things in NSTabView.m.

Wolfgang