KSharedPtr breakage

Frerich Raabe raabe at kde.org
Sun Oct 23 16:39:18 BST 2005

On Sunday 23 October 2005 05:52, Hamish Rodda wrote:
> This practice is commonplace throughout at least KSycocaEntry.

For the record, stuff like this is not all that un-common in KSycoca either 
(from KBuildServiceTypeFactory::findServiceTypeByName):

   KSycocaEntry::Ptr servType = (*m_entryDict)[ _name ];
   if (!servType.data())
      return 0;
   return (KServiceType *) ((KSycocaEntry*)servType.get());

Looks to me as if somebody couldn't really decide whether to use shared 
pointers or not, and ended up happily converting back and forth between dumb 
and shared pointers.

> I tried to 
> port it over to 100% shared pointers, but encountered a problem with
> covariant returns - KSharedPtr can't be used (in its current form) in a
> covariant return with different class types, and you can't assign from
> KSharedPtr of different class types either (only via the dumb pointer
> method above, hence it's no good).  So, KSycocaFactory::create() won't
> compile in subclasses.  I can't think of a great solution here.

I added a template constructor and a template assignment operator to 
KSharedPtr. I'm currently rebuilding kdelibs which takes ages on this laptop, 
but I'm already past kdecore (which means, past ksycoca.cpp and past 
kprotocolinfo_), so I'm positive. I hope I don't forget to attach a patch to 
this mail which shows these changes.

I also added an 'isUnique' function which returns whether a given KSharedPtr 
is the only one referencing the pointee (I saw that Stephan had to tweak 
addressee.src.cpp a bit, and this function is meant to be used there) but 
left it in.

> For now, i'm planning to comment out the delete line in KSharedPtr (i know,
> not good) and keep working on kate ;) but if anyone is interested in how
> far i got, my patch is at
> http://members.optusnet.com.au/~hamishrodda/kdelibs-ksharedptr-20051023.pat

I'm currently rebuilding kdelibs with that page.

- Frerich
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