Help with extending QTableWidgetItem

leotocca

Hi, this is my first time programming a gui using QtWidgets (and my first time programming with a gui other than VB5). I need to develop for a university lab a simplified spreadsheet (with only average, maximum, minimum and sum as possible operations) using Qt and the observer design pattern. From what I understand I can create a Cell class that extends QTableWidgetItem (which needs to be both an observer and a subject,), and a Spreadsheet that extends QTableWidget instead. I would like to be able to "save" in the cell either a double value or a formula (so I think a string). however, I can't figure out how to make it so that through the GUI I can edit the cell in such a way that it can then be used by other cells. Unfortunately, I don't think I can use "signals" (for example the cellActivated signal) since the logical part of updating the values is up to me.

Here are the definitions of my class in the Cell.h file

class Cell : public QTableWidgetItem, public Subject, public Observer {
    // every cell is both a Subject and an Observer
public:
    // TODO: find how the constructor must be
    //Cell(double v);
    ~Cell() override = default;

    void setValue(double v);
    double getValue() const;

    void setData(int role, const QVariant &value) override;
    double getData();

    void setCustomValue(bool cv);
    bool checkCustomValue() const;

    void selectCells(std::list<std::shared_ptr<Cell>> cs);
    void addCell(Cell& c);
    std::list<double> extractValues(std::list<std::shared_ptr<Cell>>& cs);

    void Cell::setFormula(int fType, std::list<std::shared_ptr<Cell>>& involvedCells, const std::string& f);
    const std::shared_ptr<Formula>& Cell::getFormula() const ;
    void Cell::removeFormula();

    // from subject and observer

    void notify() override; // virtual is redundant
    void update() override;
    void subscribe(Observer *o) override;
    void unsubscribe(Observer *o) override;

private:
    // TODO find QT variables
    // TODO Qstring for saving formula
    QVariant value;
    // QString formula = nullptr;
    // double value;
    bool customValue = false; // variable to check if the cell has been modified since its creation
    // bool isText; maybe to check if the formula is correct or is only text
    std::shared_ptr<Formula> formula;
    std::list<std::shared_ptr<Cell>> cellSelection; // list of shared pointers to involved cells-> I want to be able to do a cell selection
    std::list<Observer *> observers;
};

For example I don't know if I need to store the variable as a double variable or a QVariant etc.

Thanks in advance to anyone who would like to answer me.