[Interest] 64-bit internal ID for QModelIndex?

Stephen Chu stephen at ju-ju.com
Tue Aug 21 22:55:38 CEST 2012

On 8/21/12 4:26 PM, Nikos Chantziaras wrote:
> On 21/08/12 22:45, Stephen Chu wrote:
>> On 8/21/12 3:35 PM, Christoph Feck wrote:
>>> On Tuesday 21 August 2012 20:55:00 Stephen Chu wrote:
>>>> Is there a way to store a 64-bit internal ID in QModelIndex? The
>>>> function QModelIndex::internalId() returns a 64-bit number but
>>>> there's no way to put one in. The constructor takes only a 32-bit
>>>> integer.
>>> Try using the overload that takes the void * pointer. The return value
>>> is 64 bit, because pointers can also be 64 bit, and C++ doesn't allow
>>> different overloads with different return values.
>> Thanks for the help. But my app is currently 32-bit. :(
> Would a pointer to a qint64 work?

Yes, it will. I was thinking about that but got stuck trying to figuring 
out how I can manage the memory since QModelIndedx does not own the 
object/memory pointed by the void*

Say I allocate a QList<int64_t> and create indices with internal pointer 
pointing to elements in the list. When I need to update the model from 
external data, I will have to re-allocate the list and the existing 
pointers will be left dangling. What is the proper steps to update the 
model data in this case?

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