Re: some unsigned/NSInteger to NSUInteger changes in -gui

[Sebastian Reitenbach]

On Tuesday, April 10, 2012 19:24 CEST, David Chisnall <address@hidden> wrote: 
 
> On 10 Apr 2012, at 18:18, Sebastian Reitenbach wrote:
> 
> > +   {
> > +     int tmp = (int)_selected_item;
> > +          [aDecoder decodeValueOfObjCType: @encode(int) at: 
> > &_selected_item];
> > +          _selected = [_items objectAtIndex: tmp];
> > +   }
> 
> No, this is still wrong, and I'm not really sure what it's trying to do...
> 
> Let's say you're on some big-endian LP64 system.  NSInteger will be a 64-bit 
> integer while int will be a 32-bit integer.  You pass a pointer to the 
> NSInteger to aDecoder, and tell it that it's a pointer to an int.  It will 
> then cast this pointer and will write a 32-bit value into the first 32 bits 
> of the ivar.  Unfortunately, because this is a big endian system, you've now 
> set the value to something about four billion times as big as it should be...
> 
> As I said in my last email, the correct form is:
> 
>       int tmp;
>       [aDecoder decodeValueOfObjCType: @encode(int) at: &tmp];
>       _selected_item = tmp;
> 
> This creates an int on the stack and passes a pointer to it to aDecoder, 
> which then loads an int-sized value and stores it in the int.  You then 
> assign this value to the ivar.  The implicit cast (you can make it explicit 
> if you prefer) will extend this to the correct size.

Thanks for your patience. Now I got it, the decoder already has the value, and 
just puts it in, where the pointer points it to. But I still think I need to 
assign
_selected = [_items objectAtIndex: tmp];

so that it will be right.

Sebastian

Index: NSTabView.m
===================================================================
--- NSTabView.m (revision 35052)
+++ NSTabView.m (working copy)
@@ -52,7 +52,7 @@
 {
   if (self == [NSTabView class])
     {
-      [self setVersion: 2];
+      [self setVersion: 3];
 
       [self exposeBinding: NSSelectedIndexBinding];
       [self exposeBinding: NSFontBinding];
@@ -550,7 +550,7 @@
       [aCoder encodeValueOfObjCType: @encode(BOOL) at: &_draws_background];
       [aCoder encodeValueOfObjCType: @encode(BOOL) at: &_truncated_label];
       [aCoder encodeConditionalObject: _delegate];
-      [aCoder encodeValueOfObjCType: "I" at: &_selected_item];
+      [aCoder encodeValueOfObjCType: @encode(NSUInteger) at: &_selected_item];
     }
 }
 
@@ -631,8 +631,17 @@
       [aDecoder decodeValueOfObjCType: @encode(BOOL) at: &_draws_background];
       [aDecoder decodeValueOfObjCType: @encode(BOOL) at: &_truncated_label];
       _delegate = [aDecoder decodeObject];
-      [aDecoder decodeValueOfObjCType: "I" at: &_selected_item];
-      _selected = [_items objectAtIndex: _selected_item];
+      if (version < 3)
+       {
+         int tmp;
+          [aDecoder decodeValueOfObjCType: @encode(int) at: &tmp];
+          _selected = [_items objectAtIndex: tmp];
+       }
+      else
+       }
+          [aDecoder decodeValueOfObjCType: @encode(NSUInteger) at: 
&_selected_item];
+          _selected = [_items objectAtIndex: _selected_item];
+       }
     }
   return self;
 }



> 
> David
> 
> -- Sent from my Cray X1