Why the destrcutors in some Qt abstract classes are not virtual?

[legendwan]

For example, in QAbstractItemModel.h, the destructor of class QAbstractItemModel is virtual, while the destructor of class QAbstractTableModel and QAbstractListModel are not virtual?
I use Qt library V4.6.2.

[lyuts]

There is no keyword 'virtual' but the destructors are virtual, because these classes inherit QAbstractItemModel whose destructor is virtual.

Consider this code:

class Base                                                                                                                                                                  
{                                                                                                                                                                           
    public:                                                                                                                                                                 
        virtual void f() { std::cout << "Base::f" << std::endl; }                                                                                                           
};                                                                                                                                                                          
 
class Derived : public Base                                                                                                                                                 
{                                                                                                                                                                           
    public:                                                                                                                                                                 
        void f() { std::cout << "Derived::f" << std::endl; }                                                                                                                
 
};
 
int main(int argc, char **argv)                                                                                                                                             
{                                                                                                                                                                           
    Base *base = new Derived();                                                                                                                                             
    base->f(); 
}

class Base                                                                                                                                                                  
{                                                                                                                                                                           
    public:                                                                                                                                                                 
        virtual void f() { std::cout << "Base::f" << std::endl; }                                                                                                           
};                                                                                                                                                                          
                                                                                                                                                                            
class Derived : public Base                                                                                                                                                 
{                                                                                                                                                                           
    public:                                                                                                                                                                 
        void f() { std::cout << "Derived::f" << std::endl; }                                                                                                                
                                                                                                                                                                            
};

int main(int argc, char **argv)                                                                                                                                             
{                                                                                                                                                                           
    Base *base = new Derived();                                                                                                                                             
    base->f(); 
}

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You'll get "Derived::f" printed. At least I'm getting this result .

[legendwan]

Yes. I got it. Thank you, lyuts!