Before you start learning what qobject_cast is, you would need to know what C++’s dynamic_cast is. Dynamic cast is all about polymorphism. C++’s dynamic cast uses RTTI (Run Time Type Information) to cast an object. But qobject_cast does this without RTTI. What is dynamic cast? For example suppose we’ve got a car factory function. Like … Read more
This answer to this question is as found here: Python PySide (Internal c++ Object Already Deleted) Apparently, assigning one widget to QMainWindow using setCentralWidget and then assigning another widget with setCentralWidget will cause the underlying c++ QWidget to be deleted, even though I have an object that maintains reference to it. Note: QMainWindow takes ownership … Read more
There are at least 2 ways. First, disconnect everything. disconnect(obj,0,0,0); //or obj->disconnect(); Second. Every connect() returns QMetaObject::Connection which can be copied or moved, so you can save some connections in the list and after some time, just iterate through the list and call disconnect() for every object. Example with one connection: QMetaObject::Connection m_connection; //… m_connection … Read more
You should use the Q_OBJECT macro for any non-templated classes that derive from QObject. Besides signals and slots, the Q_OBJECT macro provides the meta object information that is associated with given class. As stated in the documentation: we strongly recommend that all subclasses of QObject use the Q_OBJECT macro regardless of whether or not they … Read more
Any time you add a new call to the Q_OBJECT macro, you need to run qmake again. The vtables issue you’re referring to is directly related to that. Just run qmake and you should be good to go assuming there are no other issues in your code.
You should delete the debug folder of your application and run it again to correct this problem.