[Qt-interest] QAbstractProxyModel methods index, parent, rowCount, columnCount not implemented?

[Andre Somers]

Hi Stephen, anyone,

Op 18-5-2011 15:25, Andre Somers schreef:
> Op Wo, 18 mei, 2011 3:03 pm, schreef Stephen Kelly:
>> Andre Somers wrote:
>>>> I had a quick look at your CheckableProxyModel, and it does a bunch of
>>>> things wrong, such as storing QModelIndexes instead of
>>>> QPersistentModelIndexes,
>>> No, it does not do that. A QHash<QPersistentModelIndex, NodeState>  is
>>> used
>>> for storing the states. I don't know where you get that I store
>>> QModelIndex directly? I don't claim there are no mistakes in the code,
>>> but
>>> this is not one of them.
>> I was referring to QModelIndexList members in the class. I only had a
>> quick
>> look and didn't think about it very hard, but if you also store
>> QPersistentModelIndexes you might be ok. I also didn't try to run it or
>> test it. I don't mean to offend.
> None taken.
> Actually, I think you are right that there is a possible issue with the
> way I deal with retreiving the selection now. I should re-think that. The
> base storing is probably OK, but there is an issue in the way I
> implemented the API for retrieving the lists of checked and unchecked
> items. These functions are meant to be called in close succession, but I
> think I should do this differently as there is no way to guarantee that
> they will be used in this way. Thanks for pointing that out.
The critique on this aspect was correct, I think. Therefore, I have 
decided to re-design this part of the API, and came up with this solution:
Instead of the bunch of methods that all return a QModelIndexList, I 
gave CheckableProxyModel now only one method checkedState() to access 
this data. This method returns an instance of CheckableProxyModelState, 
which is is not copyable or assignable and has a private constructor. 
That is: the only way to get one, is through the checkedState() method. 
This object has methods to retreive the different QModelIndexLists by 
passing in a reference to one, and all of them return a reference to the 
CheckableProxyModelState object again so you can chain calls to it. This 
leads to code like this:

QModelIndexListselectedFiles;

     QModelIndexList  selectedDirectories;

     QModelIndexList  unselectedFiles;

     QModelIndexList  unselectedDirectories;

     m_checkProxy->checkedState()

             .checkedLeafIndexes(selectedFiles)

             .checkedBranchIndexes(selectedDirectories)

             .uncheckedLeafIndexes(unselectedFiles)

             .uncheckedBranchIndexes(unselectedDirectories);


This way, there are no QModelIndexLists that are kept around in the 
model any more, and you can still get the different lists in an 
efficient way. The CheckableProxyModelState design should encourage 
using it only in the designed way: as a result of 
CheckableProxyModel::checkedState() to be discarded after the call.

The code is on gitorious: https://gitorious.org/checkableproxymodel

I do still need to address the other issues you mentioned, but I had the 
impression that this was the most pressing one to fix. I'm looking 
forwards to comments on this approach.

André

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