How to override (re-implement) a member function in QFileSystemModel

Question

I\'ve been struggling with this for a while.

Qt\'s QFileSystemModel is really slow when fetching several hundred files because of a really bad icon fetc

Answer 1

If a function in a base class is virtual then it is virtual in derived classes as well. The following will print "C":

#include 

class A {
public:
  virtual void data() = 0;
};

class B: public A {
public:
  void data() { std::cout << "B\n"; }
};

class C: public B {
public:
  void data() { std::cout << "C\n"; }
};

int
main() {
  C c;
  A *a = &c;
  a->data();

  return 0;
}

QFileSystemDialog is derived from QAbstractItemModel in which data() is pure virtual. You couldn't even instatiate the former if it didn't override data() with its own implementation.

See http://qt-project.org/doc/qt-4.8/qabstractitemmodel.html#data