deleteLater

deleteLater is a member function of QObject in the Qt framework. It schedules the object for deletion by posting a DeferredDelete event to the object's event loop. When the event loop processes this event, the object is deleted in a safe manner, typically by invoking the object's destructor.

The primary purpose of deleteLater is to enable safe deletion of QObjects, especially widgets, without risking use-after-free errors that can occur if an object is deleted while still handling signals, slots, or pending events. It is commonly used when an object should be removed in response to an event, or after an asynchronous operation completes, but where immediate deletion could disrupt ongoing processing.

How it works in practice: calling deleteLater queues the deletion and returns immediately. The actual deletion occurs later, when control returns to the event loop of the thread that owns the object. This defers destruction to a point where no more code is running in the object's current execution context, reducing the risk of accessing freed memory.

Thread safety and scope: deleteLater can be invoked from any thread, since the deletion is scheduled through the thread-safe event queue. The actual deletion occurs in the object's thread. The object must still exist when deleteLater is called; if the object has already been deleted or is being deleted, subsequent calls become no-ops. Note that QObject parent-child relationships remain the usual mechanism for memory management: deleting a QObject will ultimately affect its children as part of destruction.

Example: myWidget->deleteLater(); This is a common pattern when a widget should be removed after its current operations complete.