How Qt Slots Work?

In Qt, slots are used to define how signals are handled. Slots are implemented as member functions in a class, and they must be declared as such in order to be accessible.

When a signal is emitted, the corresponding slot is executed. In order for this to happen, the slot must be connected to the signal.

This is done using the connect() function.

The connect() function takes as arguments the address of the object that emits the signal, the name of the signal, and the address of the object that receives the signal (the slot).

It is also possible to specify additional arguments for the connection. These arguments are passed to the slot when it is executed.

The connect() function returns a boolean value that indicates whether or not the connection was successful.

Once a connection is made, it cannot be changed without first disconnecting it. This can be done using the disconnect() function.

The disconnect() function takes as arguments the address of the object that emits the signal, the name of the signal, and the address of the object that receives the signal (the slot).

If no connection exists between the specified objects and signals, false is returned. Otherwise, true is returned.

It is also possible to specify additional arguments for the disconnection. These arguments must match those used when making the connection.

Otherwise, false is returned.

The most common way to use slots is by connecting signals to them from other objects. For example, consider a button that emits a clicked() signal when it is clicked:

The clicked() signal can be connected to a slot in another object, such as a MainWindow:

When this button is clicked, it will emit a clicked() signal. This signal will be received by MainWindow’s clicked() slot, which will then execute its code.