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

[Sebastian Reitenbach]

On Tuesday, April 10, 2012 17:39 CEST, Wolfgang Lux <address@hidden> wrote: 
 
> Sebastian Reitenbach wrote:
> 
> > 
> > On Monday, April 9, 2012 22:37 CEST, Fred Kiefer <address@hidden> wrote: 
> > 
> >> I just checked the code in base and Eric seems to be right here. The >> 
> >> type check code in NSUnarchiver (we aren't talking about keyed coding >> 
> >> here) has a lot of HACK warnings, but it seems to do what we need here, 
> >> allow for different integer types to be used interchangeable.
> >> 
> >> Please go ahead and apply this change.
> > 
> > Argh, now I recognized, I seem to broke at least Fisicalab and Addresses on 
> > startup:
> > 
> > 2012-04-10 17:05:54.485 FisicaLab[10884] Exception occured while loading 
> > model: expected unsigned int and got int
> > 2012-04-10 17:05:54.508 FisicaLab[10884] Failed to load Gorm
> > 2012-04-10 17:05:54.528 FisicaLab[10884] Cannot load the main model file 
> > 'Fisica.gorm'
> > 
> > putting a breakpoint at NSException, I end up here:
> > 
> > Breakpoint 2, -[NSException raise] (self=0x205b8f608, _cmd=0x20d881a50) at 
> > NSException.m:956
> > 956       if (_reserved == 0)
> > Current language:  auto; currently minimal
> > (gdb) bt
> > #0  -[NSException raise] (self=0x205b8f608, _cmd=0x20d881a50) at 
> > NSException.m:956
> > #1  0x000000020d409b65 in +[NSException raise:format:] (self=0x20d8816a0, 
> > _cmd=Variable "_cmd" is not available.
> > ) at NSException.m:835
> > #2  0x000000020d4c88c2 in -[NSUnarchiver decodeValueOfObjCType:at:] 
> > (self=0x206e20088, _cmd=0x20cf0dea0, type=0x20cd10b20 "I", 
> > address=0x20dc2fd70) at NSUnarchiver.m:247
> > #3  0x000000020cb2972b in -[NSTabView initWithCoder:] (self=Variable "self" 
> > is not available.
> > ) at NSTabView.m:634
> > #4  0x000000020d4c8200 in -[NSUnarchiver decodeValueOfObjCType:at:] 
> > (self=0x206e20088, _cmd=0x20d8dda40, type=0x20d728790 "@", 
> > address=0x20dc2df70) at NSUnarchiver.m:662
> > #5  0x000000020d4c627d in -[NSUnarchiver decodeArrayOfObjCType:count:at:] 
> > (self=0x206e20088, _cmd=Variable "_cmd" is not available.
> > ) at NSUnarchiver.m:574
> > #6  0x000000020d3459de in -[GSMutableArray initWithCoder:] 
> > (self=0x20721e648, _cmd=Variable "_cmd" is not available.
> > ) at GSArray.m:553
> > #7  0x000000020d4c8200 in -[NSUnarchiver decodeValueOfObjCType:at:] 
> > (self=0x206e20088, _cmd=0x20cf42dd0, type=0x20cd157ca "@", 
> > address=0x7f7fffff8798) at NSUnarchiver.m:662
> > #8  0x000000020cb79dc3 in -[NSView initWithCoder:] (self=Variable "self" is 
> > not available.
> > ) at NSView.m:4740
> > #9  0x000000020d4c8200 in -[NSUnarchiver decodeValueOfObjCType:at:] 
> > (self=0x206e20088, _cmd=0x20d8dda40, type=0x20d728790 "@", 
> > address=0x20dc2dc00) at NSUnarchiver.m:662
> > #10 0x000000020d4c627d in -[NSUnarchiver decodeArrayOfObjCType:count:at:] 
> > (self=0x206e20088, _cmd=Variable "_cmd" is not available.
> > ) at NSUnarchiver.m:574
> > ...
> > (gdb) frame 3
> > #3  0x000000020cb2972b in -[NSTabView initWithCoder:] (self=Variable "self" 
> > is not available.
> > ) at NSTabView.m:634
> > 634           [aDecoder decodeValueOfObjCType: "I" at: &_selected_item];
> > (gdb) list
> > 629                 }
> > 630             }
> > 631           [aDecoder decodeValueOfObjCType: @encode(BOOL) at: 
> > &_draws_background];
> > 632           [aDecoder decodeValueOfObjCType: @encode(BOOL) at: 
> > &_truncated_label];
> > 633           _delegate = [aDecoder decodeObject];
> > 634           [aDecoder decodeValueOfObjCType: "I" at: &_selected_item];
> > 635           _selected = [_items objectAtIndex: _selected_item];
> > 636         }
> > 637       return self;
> > 638     }
> > 
> > but in AppKit/NSTabView.h:  
> > I have: NSUInteger _selected_item;
> > 
> > so I don't really understand, why the decoder thinks its getting an int?
> > 
> > Someone can help me understand how I broke that?
> 
> The problem is that existing archives are coded using int values rather than 
> unsigned int values.
> The only safe way to change the encoding from signed to unsigned values and 
> vice versa is to increment the version number for objects. Furthermore you 
> will need to check the version number while decoding and either decode a 
> signed int (if you find an old object version) or an unsigned (if you find a 
> new object version).
> However, I don't think this is worth the hassles, so its better to revert 
> your change (and if you are paranoid you could raise exceptions while 
> encoding and decoding if the _selected_item attribute is out of range).

Thanks Wolfgang for your quick answer.

I thought one of the goals is to be more compatible with Coocoa, and there its 
an NSUInteger. therefore I decided to follow your first suggestion, bumping the 
NSTabView class version, and add a check to the decoder method. There is 
already another check for version < 2.
The patch below now again makes the broken Apps work for me.

Is that OK, or is there more that would need to be fixed?

thanks,
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];
@@ -631,7 +631,10 @@
       [aDecoder decodeValueOfObjCType: @encode(BOOL) at: &_draws_background];
       [aDecoder decodeValueOfObjCType: @encode(BOOL) at: &_truncated_label];
       _delegate = [aDecoder decodeObject];
-      [aDecoder decodeValueOfObjCType: "I" at: &_selected_item];
+      if (version < 3)
+        [aDecoder decodeValueOfObjCType: "i" at: &_selected_item];
+      else
+        [aDecoder decodeValueOfObjCType: "I" at: &_selected_item];
       _selected = [_items objectAtIndex: _selected_item];
     }
   return self;



> 
> Wolfgang
>