NSNumberFormatter segfault when using -initWithCoder

[Eric Wasylishen]

Hey.
-[NSNumberFormatter init] has this block of code:

  internal->_behavior = _defaultBehavior;
  internal->_locale = RETAIN([NSLocale currentLocale]);
  internal->_style = NSNumberFormatterNoStyle;
  internal->_symbols = NSZoneCalloc (z, MAX_SYMBOLS, sizeof(id));
  internal->_textAttributes = NSZoneCalloc (z, MAX_TEXTATTRIBUTES, sizeof(id));
  internal->_attributes = NSZoneCalloc (z, MAX_ATTRIBUTES, sizeof(int));

which allocates some C arrays.  However, these ivars are never initialized if 
you use -initWithCoder:, and so if you call -setDecimalSeparator: on a instance 
loaded from a nib, you'll get a segfault in this line of code in the SET_SYMBOL 
macro:

 if (internal->_symbols[key])

since the internal->_symbols will be NULL at that point.


I have a couple of comments about this:

1. The SET_SYMBOL macro wasted me a significant amount of time because I had to 
expand it by hand to locate the segfault. Is there a reason this isn't a 
private instance method instead of a macro? (same with SET_TEXTATTRIBUTE, 
SET_ATTRIBUTE, SET_BOOL, GET_SYMBOL, GET_ATTRIBUTE, GET_BOOL).
Sorry to sound negative; the new NSNumberFormatter implementation looks really 
nice otherwise :-)

2. I've seen this mistake (-initWithCoder not doing everything -init does) 
before, and I expect it occurs elsewhere in GNUstep. Do we have a policy on how 
to prevent this from happening in the future? i.e. what's the right way to 
implement -initWithCoder and -init? I think we should have a standard pattern 
we use everywhere.

 - We don't want them to share large chunks of copy-and-pasted code since this 
is error prone.
 - Calling -init (or the designated initializer) directly from -initWithCoder 
could cause problems since it could conflict with the required call to [super 
initWithCoder: ];
 - The only idea I can think of right now is factoring out the common code in 
to a static function like this:

- (id) init
{
        self = [super init];
        privateInit(self);
        return self;
}

- (id)initWithCoder: (NSCoder*)coder
{
        self = [super initWithCoder: coder];
        privateInit(self);
        
        if ([coder containsValueForKey: @"foo"]) [self setFoo: [coder 
decodeObjectForKey: @"foo"]];
        if ([coder containsValueForKey: @"bar"]) [self setBar: [coder 
decodeObjectForKey: @"bar"]];
        ...
        return self;
}

static void privateInit(MyClass *self)
{
        self->someCArray = malloc(100);
        self->someValue = 123;
        ...
}

Note that the privateInit function only sets up ivars belonging to the current 
class, so each superclass would have its own privateInit function to set up the 
ivars belonging to that superclass.

How does that pattern look?

--Eric