CODEWITHSUNDEEP
c++qtqobjectqlist
Remi
Remi

Reputation: 766

QObject set QList as parent using setParent()

I'm trying to use QObject tree delete mechanism to delete the list and all QObjects that are stored in the list. Qt is still my very week area...

QList<QObject*>* list = new QList<QObject*>();
QObject* obj1 = new QObject();
QObject* obj2 = new QObject();
obj1->setParent(obj2);
obj2->setParent((QObject*)list);

I got "Segmentation fault" at last line. Can't the QList be used as a parent? Doesn't it inherit from QObject?

Edit:

The main question - is it possible to conveniently delete the list and all list elements without extending the QList class? This need to be called by client so it have to be simple.

I would like to simply call:

delete list;

and not

qDeleteAll(list);
delete list;

Upvotes: 0

Views: 1385

Answers (2)

cmannett85
cmannett85

Reputation: 22346

No. QList does not inherit from QObject. If you want to delete the contents of the list easily, you can use qDeleteAll(list).

Edit: This is untested, and there may be problems from the base class not having a virtual destructor - but give it ago.

template < class T >
class MyList : public QList< T >
{
    static_assert( std::is_pointer< T >::value,
                   "T must be a pointer." );
    //  Constructors...
    ...
    virtual ~MyList() { qDeleteAll( *this ); }
 }

Upvotes: 1

evilruff
evilruff

Reputation: 4085

option 1)

QList<QObject*> list;

.. somewhere in the code

QObject * obj = new QObject();
list << obj;

... 

then 


onDelete() {    // variant 1
       QObject * ptr;
       foreach(ptr, list) {
          delete ptr;
       }
       list(clear);
}

onDelete() { // variant 2
     qDeleteAll(list);
}

option 2)

 QObject * parent = new QObject();

 somewhere in a code 
 ...
 QObject * child1 = new QObject(parent);
 QObject * child2 = new QObject(parent);


 onDelete() {
     delete parent;   // all children deleted automatically
 }

UPD:

From your question update, I can consider that you don't QList at all, just use QObject provided functionality, and if you need children use appropriate childer() method which will give you QList

Upvotes: 0

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