[Qt-interest] Iterators and implicitly shared containers

[Malyushytsky, Alex]

>>however, the *it=2; should recognize that the ref count > 1, and
>>do a detach/deep copy as necessary no??
>>
>>Soctt

This is what I would expect,
but I afraid that you can't achieve it at least with current implementation of iterators/containers sharing in Qt.

The way to fix your code is to obtain iterator after assignment.
Modification below will produce results you expected, cause detachment will be done when v1.begin() is called.

If I were you I would try to report the bug. If not fixed it will be good at least to have a special warning in documentation which identifies possible problem.


#include <QtCore/QCoreApplication>
#include <QtDebug>
#include <QVector>

int main(int argc, char *argv[])
{
  QCoreApplication a(argc, argv);

  QVector<int> v1 = QVector<int>() << 1;
  const QVector<int> v2 = v1;

  QVector<int>::iterator it = v1.begin();
  *it = 2;
  //v1[0] = 2;

  qDebug() << "v1:" << v1 << ", v2:" << v2;
  return 0;
}

Regards,
   Alex


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