No sort problem but a basic c(++) problem - you pass the parameters to unzip() by value instead by reference so how should the those variables be updated outside?

There are examples and detailed descriptions on both pages I linked.

Btw. to put my money where my mouth is this is my proposal for this problem. Yes, I'm assuming the format is fixed and search operations won't return -1. If that isn't the case you can add one if to range check the indices. std::ranges::sort(vec, [](QStringView a, QStringView b) { int pos_a = a.lastIndexOf(' '); int pos_b = b.lastIndexOf(' '); int int_a = a.sliced(pos_a).toInt(); int int_b = b.sliced(pos_b).toInt(); return int_a < int_b; }); Do you consider this unreadable? And no, this is not fully optimized either, because it does the same int conversions multiple times, but I consider something like this to be a "good enough starting point" and in-depth optimization is possible if need arises e.g. by caching the conversions or changing the data structure. EDIT Just after posting I realized you can do the QStringView creation right in the params, so even simpler.

@CybeX Well, the debugger shows a as "<not accessible>", so unless its value has been optimized out that seems to be the cause of the SEGV. I admit I don't know how/why, assuming you only put items into fileInfoImageList via the code you show. I would start by just checking you can visit/print out all the QFileInfos in your lists before you start the std::sort()? I would also force a complete rebuild just to make sure. The placement of the debug breakpoint on line #319 which is blank looks odd to me, it's not supposed to do that....

Thanks that worked

@VRonin said in Implement QSortFilterProxyModel with own TreeModel?: Good guess, can you show us your code? I solved it: I had to pass the parent index (tree structure), so the line should look like this: QVariant data = m_proxy->data(m_proxy->index(index.row(), 4, index.parent()));

@JonB, thanks, i will try your implementation.

@VRonin Thanx mate

@Kofr mapFromSource() and mapToSource() are enough. The default implementation should depend on these methods only.

Yeah but the user also want to be able to reorder things as he wants, not just sort (ie, put this row here, drag all my selection at this position, invert these two rows, ...)

Is QCollator::compare a good option for this? I mean, I simply implement a sorting algorithm based on the result from QCollator::compare. Usually the number of files will be limited to ~3000.

I figured it out, that information is the header of the QTreeWidget. So, the code to extract this value from within a QTreeWidgetItem is: self.treeWidget().header().sortIndicatorOrder() and this you can check for being equal to Qt.DescendingOrder (or Qt.AscendingOrder if you prefer).