CODEWITHSUNDEEP
c++qtunique-ptr
lhahn
lhahn

Reputation: 1241

Error using Qt and unique pointers

I am currently working on an interface for an random application. In the interface I have a QListView, which have three buttons related to it. The first one is add, which adds a new item on the widget, this button works fine. The problem comes with the clear button:

void NeuralNetwork::on_clearButton_clicked() {
    this->model.get()->clear();
    this->item.clear();
}

as you see both model and item are attributes of this class. They are declared as this:

std::unique_ptr<QStandardItemModel> model = unique_ptr<QStandardItemModel>(new QStandardItemModel());
vector<unique_ptr<QStandardItem>> item;

Initially I was using normal pointers, but as I searched on the internet, people were recommending using unique pointers to handle memory management.

I think there is something wrong with 

this->model.get()

but I don't know exactly, since I have no experience with smart pointers. Note that the program doesn't get build errors, it works fine until I press the clear button on the interface, then the program crashes:

The program has unexpectedly finished.

Upvotes: 0

Views: 536

Answers (1)

Werner Erasmus
Werner Erasmus

Reputation: 4076

Be carefull, as QStandardItemModel has ownership of standard items. Therefore you would get a double delete when you associated a standard item with a unique pointer.

In general, with Qt you don't need to use unique pointers, as parents already have ownership of their children.

Upvotes: 2

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