[sword-devel] VerseKey semantics

[Troy A. Griffitts]

You can reference a module's internal key directly and use that 
reference to position a module just fine, but you shouldn't hold on to 
the reference.  A subsequent call to a module's setKey method will often 
invalidate any previous reference to the module's internal key.

If you'd like to use a module's internal key instead of creating your 
own, if possible gain the reference each time with mod->getKey() (or as 
you have done with the (SWKey *) cast operator).  Or else be careful not 
to call mod->setKey, but I would not recommend the latter.


On 12/07/2014 06:27 PM, Karl Kleinpaste wrote:
> I asked Troy about this in IRC a bit yesterday, but I ran into 
> problems today and I'm in need of clues.
>
> In the av11n world, I've had to convert all VerseKey initialization to 
> be v11n-sensitive.  Mostly, I'd prefer just to use a module's own key 
> directly:
>
> VerseKey *k = (VerseKey *)(SWKey *)(*mod);
>
> The problem I've got is that there are a number of instances where 
> subsequent operations on k cause crashes or give exciting results.  
> For one, when trying to fill a navbar book selector, the 2nd call to 
> k->setTestament(1) (populating OT books) segfaults.  Note, not the 1st 
> call, rather it's the 2nd, every time.  It's become necessary to 
> create the key the other way:
>
> VerseKey *k = (VerseKey *)mod->createKey();
>
> and then calls to k->setTestament(1) work just fine.  Of course I have 
> to remember to
> delete k;
> which is mildly annoying to have to do, and wasn't necessary when 
> using the module's own key.
>
> Can anyone offer reasoning why the VerseKey from the module would have 
> trouble with this sort of use, and why an independently-created key 
> from the same module works fine?
>
>
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