What does @pyqtSlot() do?

"When working with Qt slots and signals in PyQt6 you will discover the @pyqtSlot decorator. This decorator is used to mark a Python function or method as a slot to which a Qt signal can be connected. However, as you can see in our signals and slots tutorials you don't have to use this. Any Python function or method can be used, normally, as a slot for a Qt signals. But elsewhere, in our threading tutorials we do use it. What's going on here?"

"Although PyQt6 allows any Python callable to be used as a slot when connecting signals, it is sometimes necessary to explicitly mark a Python method as being a Qt slot and to provide a C++ signature for it. PyQt6 provides the pyqtSlot() function decorator to do this. Connecting a signal to a decorated Python method has the advantage of reducing the amount of memory used and is slightly faster."

PyQt6 permits any Python callable to be connected to a Qt signal, but pyqtSlot can explicitly mark a method as a Qt slot and provide a C++ signature. Decorating a method produces a native Qt slot, while leaving a method undecorated causes PyQt6 to create a proxy wrapper that supplies a native slot to Qt. The decorator reduces memory usage and yields slightly faster calls. The decorator becomes necessary in threaded situations because signal connections are handled differently for native slots versus proxy-wrapped slots. In most simple signal-slot uses the decorator is optional.

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