what it means by 'Qobject has a parent'

[JadeN001]

moveToThread() will fail if the QObject has a parent according to QtDocument.
i don't know what it means by "QObject has a parent".
how can i identify that any QObject has a parent or not

[Gojir4]

Hi,

QObject takes an optional parent in its constructor.

QObject(QObject *parent = nullptr)

You probably created an instance of a class inheriting from QObject, and pass "this" as the parent. In this case just remove the "this" from your code

//MyObject *o = new MyObject(this);
MyObject *o = new MyObject;

By the way you can check if an object has a parent using QObject::parent().

[mrjj]

Hi
Its normally the first parameter in constructor.

https://mayaposch.wordpress.com/2011/11/01/how-to-really-truly-use-qthreads-the-full-explanation/

as you see here for the worker class

QThread* thread = new QThread;
Worker* worker = new Worker(); <<< no parent given
worker->moveToThread(thread);

[koahnig]

@JadeN001

A lot of Qt objects are inheriting from QObject and allow to set a parent, which will be handed down to QObject.
Either you set a parent to take care of handling the object or you leave it as a null pointer (no parent).

See more details

[JadeN001]

@koahnig i am new in qt.which type of object(s) can be called as a QObject. As u have mention Qt objects. what is Qt objects?
When a QObject receives a queued signal or a posted event, the slot or event handler will run in the thread that the object lives in. what QObejct means in this sentence.

[koahnig]

@JadeN001

Here is an example for QWidget:

The rest you find in the documentation for each class.

In this case QWidget is directly inheriting from QObject and it is inherited by lot of other classes.