Is it mandatory to use the pyqtSlot decorator?

Question

When I want to connect a QPushButtonto an event, for example, I use a method and add it as event callback clicked.connect

For example:

def buildUi(self):

    self.buttonSubmitText  = QtWidgets.QPushButton("Enviar")

    self.textChat = QtWidgets.QLineEdit()

    self.buttonSubmitText.clicked.connect(self.onSubmitText)



 def onSubmitText(self):

    text = self.textChat.text()

    message = create_message(self.selectedUser["id"], text)

    formattedText = self._buildChatText(message)

    self.viewChat.insertHtml(formattedText)

    self.textChat.setText("")

But I’ve seen several examples on the internet where it’s added QtCore.pyqtSlot() as decorator. That is, the code looks like this:

 @QtCore.pyqtSlot()
 def onSubmitText(self):

    text = self.textChat.text()

    message = create_message(self.selectedUser["id"], text)

    formattedText = self._buildChatText(message)

    self.viewChat.insertHtml(formattedText)

    self.textChat.setText("")

I would like to know what is the impact of using or not using this decorator? It makes a difference?

It is mandatory to use it or not?

Answer 1

As stated in Soen, this link explains about the decorated (translated):

Although Pyqt4 allows anything that can be called in Python (as methods) to be used as a slot when connecting signals, it is sometimes necessary to explicitly mark a Python method as a slot Qt and provide a subscription c++ for him. Pyqt4 provides the decorator pyqtSlot() function to do this.

And this other passage (translated):

When connecting a signal with a decorator method has the advantage in reducing the memory consumption used, thus being a little faster.

If you don’t use the slots, signal connection mechanism has to manually calculate all type conversions to map function signatures c++ for Python functions, when slots are used, type mapping can be explicit.