Pyside6 Signal to Slot in different class

britesc

Hi,
I have a class that creates Previous and Next buttons on a TabWidget.
I also have the standard class MainWindow created by QApplication.
My aim is to emit a signal from the Previous and Next Buttons that will be actioned within the MainWindow.
If I click either of these 2 buttons I get the expected "Previous Pressed" printed to console.

But, nothing appears to function in the MainWindow.
I am sending a signal emit(64) for previous and emit(65) for next from the TabWidget Class file.

I am fairly convinced that I have ingested every example, video, book reference to using Signals and Slots.

Here is my code. Code someone please show me where I am going wrong. Thank you.

Kind regards,

jB

mainwindow.py

...
from PySide6.QtCore import (
    Slot,
    Signal
)

class MainWindow(QMainWindow, Ui_MainWindow):

    """ The MainWindow Class. """
    def __init__(self, app) -> None:
        super().__init__()
        self.setupUi(self)  # type: ignore
        self.app = app  # declare an app member
...

    @Slot(int)
    def signals_received(self, sig) -> None:
        print(f"Signal Received {sig}")
        match sig:
            case 64:
                print("Number 64 Received")
            case 66:
                print("Number 65 Received")
            case _:
                print("Got a different Signal")

othercclass.py

...
from PySide6.QtCore import (
    Slot,
    Signal
)

class tab_initial_setup(QWidget, initial_ui.Ui_tab_initial_setup):
    signal_pb_previous = Signal(int)    
    def __init__(self) -> None:
        super().__init__()
        self.setupUi(self)  # type: ignore
        self.pushButton_navigation_previous.clicked.connect(self.button_pushed_previous)

    @Slot(int)  
    def button_pushed_previous(self) -> None:
        print("Previous Clicked")
        self.signal_pb_previous.emit(64)
        print("Previous Signal Emitted")
   ...

I have no way of knowing if the problem lies within the Signal or the Slot. I have tried VSCode debug but nothing shows up. So is there a way of seeing if a Signal is actually being emitted?

So please, can anyone help me unravel this conundrum that is giving me sleepless nights.

Thanks and kind regards,
jB

britesc

@JonB

added to mainwidow.py

initial_tab_setup.signal_pb_previous.connect(self.signals_received)

and now get confirmation of emitted signal and slot receipt.
Thank you for you help.
Kind regards,
jB

JonB

@britesc said in Pyside6 Signal to Slot in different class:

But, nothing appears to function in the MainWindow.

I am fairly convinced that I have ingested every example, video, book reference to using Signals and Slots.

From your reading you know that every slot must be connected to a signal. You do so, for example, for pushButton_navigation_previous.clicked. Where is your connect() statement for your signal_pb_previous signal? This has nothing to do whether the connection is across classes or not.

britesc

@JonB
Thank you for your response.
I agree with you.
But, I think I have confused myself into a corner as to the semantics.
I just don't know how to write or where to put the connect.
In which class?
Could you please indicate what I should code and where I should put it.
After that my 101 should be completed.
Thank you and kind regards,
jB

britesc

@JonB

added to mainwidow.py

initial_tab_setup.signal_pb_previous.connect(self.signals_received)

and now get confirmation of emitted signal and slot receipt.
Thank you for you help.
Kind regards,
jB

JonB

@britesc
Qt connections must be made between instances of the signalling class and the slot class.

You do not show where, but somewhere you create an instance of tab_initial_setup class. (It might be in your self.setupUi(self) if you created it in Designer, I don't know; perhaps not since tab_initial_setup is its own class.). You need to find that.

Let's say somewhere (in MainWindow or Ui_MainWindow or setupUi()) you have something like self.tab = tab_initial_setup(). Then you would need:

self.tab.signal_pb_previous.connect(self.signals_received)

in somewhere like MainWindow's __init__() method, after the self.tab = tab_initial_setup() has executed.