Problems with custom sorting of QTreeWidget (problem solved)

[Radek]

I need to sort a tree. The tree contains TreeItems:

class TreeItem : public QTreeWidgetItem
{
  public :
 
    enum type_t
    {
      tFile,
      tDir
    };
 
    QString    *data;
    type_t      dtype;
    bool        parsed;
 
    QStringRef  title;
    QStringRef  note;
    QStringRef  auth;
    QStringRef  src;
    QStringRef  date;
    QStringRef  url1;
    QStringRef  url2;
    QStringRef  txt;
    int         idate;
 
    TreeItem();
    virtual ~TreeItem();
 
    virtual bool operator < ( const QTreeWidgetItem& other ) const;
 
    bool SetData( const QString *fd );
    bool SetType( const type_t it );
};

class TreeItem : public QTreeWidgetItem
{
  public :

    enum type_t
    {
      tFile,
      tDir
    };

    QString    *data;
    type_t      dtype;
    bool        parsed;

    QStringRef  title;
    QStringRef  note;
    QStringRef  auth;
    QStringRef  src;
    QStringRef  date;
    QStringRef  url1;
    QStringRef  url2;
    QStringRef  txt;
    int         idate;

    TreeItem();
    virtual ~TreeItem();

    virtual bool operator < ( const QTreeWidgetItem& other ) const;

    bool SetData( const QString *fd );
    bool SetType( const type_t it );
};

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The tree is populated from a (application modal) dialog:

void MyFrame::ShowDirDlg()
{
  OpenDlg->ShowDlg(true);                             //  show the dialog
 
  if( OpenDlg->current != nullptr )                    //  if selected item acceptable
  {
    MyTraverser dt;                                            //  MyTraverser will load data and populate the tree
 
    ui.wndTree->setSortingEnabled(false);       //  start updating the tree
    ui.wndTree->clear();
    ui.wndText->clear();
 
    dt.tree = ui.wndTree;
    dt.traverse(OpenDlg->current->fname);     //  populate the tree
 
    ui.wndTree->setSortingEnabled(true);        //  sort
    ui.wndTree->sortItems(0,Qt::AscendingOrder);
  }
}

void MyFrame::ShowDirDlg()
{
  OpenDlg->ShowDlg(true);                             //  show the dialog

  if( OpenDlg->current != nullptr )                    //  if selected item acceptable
  {
    MyTraverser dt;                                            //  MyTraverser will load data and populate the tree

    ui.wndTree->setSortingEnabled(false);       //  start updating the tree
    ui.wndTree->clear();
    ui.wndText->clear();

    dt.tree = ui.wndTree;
    dt.traverse(OpenDlg->current->fname);     //  populate the tree

    ui.wndTree->setSortingEnabled(true);        //  sort
    ui.wndTree->sortItems(0,Qt::AscendingOrder);
  }
}

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Everything works perfectly except for sorting. The operator < is never called. Without sortItems() the items get sorted but in descending order. With sortItems() the items get sorted in asscending order but still using default (sort by item labels). What am I doing wrong? How to force the tree using my operator < ?

-----------------------------------

Edit: Never mind, problem solved. I needed to rebuild instead of build after adding the operator to the header. I've seen this bug (it's definitely a "make" bug) many times even if I am a complete newbie in Qt. The bug consists in:

- overlooking patched headers and using the old ones somehow. (You can see this while debugging the app.)
- overlooking patched .ui files (even if you patch from the Creator project and not from the Designer) and using the old ones. (In fact, using the old "ui_form.h" and "ui_form.cpp" files.)

When this happens, the project "compiles ok" and then crashes mysteriously. Step 1 (be polite): rebuild. Step 2 (be rude): quit Creator, delete debug and release folders, restart, build. Step 1 is usually enough. In the "sort" cause, the project did not crash so that I forgot to rebuild.

I wonder whether the bug is specific for Linux Debian or whether the bug has been seen elsewhere, too.