How does the QTableWidget sort a column?

[codemonkey]

As I've written in another thread, I have subclassed

class QInt64Item : public QTableWidgetItem
{
public:
    QInt64Item(qint64 data=0);
    QVariant data(int role) const;
    bool operator< ( const QInt64Item& other ) const;
protected:
    qint64 m_data;
};

class QInt64Item : public QTableWidgetItem
{
public:
    QInt64Item(qint64 data=0);
    QVariant data(int role) const;
    bool operator< ( const QInt64Item& other ) const;
protected:
    qint64 m_data;
};

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and sorting the data (clicking on the header of the table) works (=sorted as expected) as long as

QInt64Item::data(Qt::DisplayRole)

QInt64Item::data(Qt::DisplayRole)

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returns the qint64 variable m_data, and not QString::number(m_data).

This puzzles me. What sort is acctually beeing run when clicking in the table header?

My comparison function

bool QInt64Item::operator< ( const QInt64Item& other ) const
{
    return m_data < other.m_data;
}

bool QInt64Item::operator< ( const QInt64Item& other ) const
{
    return m_data < other.m_data;
}

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can't possible be used for this.
So how does this acctually work?

[codemonkey]

I solved it.
Here is the code.

bool QInt64Item::operator< ( const QTableWidgetItem& other ) const
{
    qDebug()<<"jamför";
    return m_data < ((QInt64Item&)other).m_data;
}

bool QInt64Item::operator< ( const QTableWidgetItem& other ) const
{
    qDebug()<<"jamför";
    return m_data < ((QInt64Item&)other).m_data;
}

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Notice that the parameter is of the type QTableWidgetItem&. That was my mistake. Now it works, and I can add pretty-printing

QVariant QInt64Item::data(int role) const
{
    QLocale defaultLocale;
    if (role==Qt::DisplayRole)
        return defaultLocale.toString(m_data);

QVariant QInt64Item::data(int role) const
{
    QLocale defaultLocale;
    if (role==Qt::DisplayRole)
        return defaultLocale.toString(m_data);

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Nice!