[interfacekit] Re: BLooper::SetCommonFilterList() mod

> 
> Hey, all.  Thought I would ping for opinions before I did something 
> rash. ;)  Currently the OBOS and R5 implementations of BLooper will 
> segfault if you do this:
> 
>       BLooper Looper1;
>       BLooper Looper2;
>       BList* filters =3D new BList;
>       filters->AddItem(new BMessageFilter('1234'));
>       Looper1.SetCommonFilterList(filters);
>       Looper2.SetCommonFilterList(filters);
> 

From the BeBook:
SetCommonFilterList() deletes the current filter list and its contents, and 
replaces it with filters. All elements in filters must be BMessageFilter 
pointers.
>>The BLooper takes ownership of all objects in filters, as well as filters 
>>itself. 
If filters is NULL, the current list is deleted without a replacement. 
CommonFilterList() returns a pointer to the current list. You can examine 
the list but you shouldn't modify or delete it. 

This clearly indicated that a filter list can only be used with one looper.

> The segfault happens on destruction of Looper1 because Looper2 has 
> already deleted filters, leaving us with a dangling pointer.  Very bad.  
> What I'd like to do is add a check on the first filter of the list to 
> see if it belongs to another looper and if it does, go to debugger with 
> a message like AddCommonFilter() ("A MessageFilter can only be used 
> once.") and then return without setting the list.  I could check the 
> whole list, but that would be more time consuming and only a real 
> pervert would populate a list with filters in different states of 
> ownership. ;P
> 
> Anyone see any problem with this=3F
No, would be ok for me. Except that there may be programs
already doing it, but since they will crash anyway, just add
the check.

Marcus

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