QObjectConnect

QObjectConnect is a fundamental mechanism in the Qt framework used for inter-object communication. It enables objects to signal that something has happened and allows other objects to respond to those signals by connecting them to their own slots. This signal-slot mechanism is a powerful and flexible way to build loosely coupled applications, where objects do not need to know about each other directly.

The basic syntax for establishing a connection is QObject::connect(sender, signal, receiver, slot). The sender is the object emitting the signal, and the receiver is the object that will perform an action when the signal is emitted. The signal is a specific event declared in the sender's class, and the slot is a function or method within the receiver's class that is invoked. Qt's meta-object system handles the introspection required to match signals and slots.

Multiple connections can be made to a single signal, meaning several objects can react to the same event. Similarly, a single slot can be connected to multiple signals. This provides a high degree of flexibility in designing application logic. QObjectConnect also supports various connection types, such as direct connections (executed immediately in the emitting thread) and queued connections (executed in the receiver's thread's event loop), which are crucial for multithreaded applications. Disconnecting signals and slots is also straightforward using QObject::disconnect. This system is a cornerstone of Qt's event-driven programming model.