[FIXED] Call and use a QtabWidget defined in the main class, in another class

Issue

I have prepared a little script to illustrate my problem. In fact I would like the button contained in tab 1 (Tab 1) to show me tab 4 (Tab 4). The QTabWidget is contained in the main class (CLASSE_Main) and I'm calling it from class 1 (CLASSE_1). I did some testing but nothing works.

Here is the script:

#!/usr/bin/python
# -*- coding: utf-8 -*-

# Imports PyQt5 -----------------------------------------------------------------------
from PyQt5.QtWidgets import (QWidget, QGroupBox, QGridLayout, QVBoxLayout, QMainWindow, 
                             QTabWidget, QWidget, QApplication, QLabel, QPushButton)
# -------------------------------------------------------------------------------------                            

import sys


class CLASSE_1(QWidget) :
    """ """
    
    def __init__(self, parent=None):
        super(CLASSE_1, self).__init__(parent)

        label_classe_1 = QLabel("I'm class 1 label")
        bouton_affichage_tab_4 = QPushButton("setCurrentIndex Tab 4")
        groupe_1 = QGroupBox()
        grid_1 = QGridLayout()
        grid_1.addWidget(label_classe_1, 0, 0)
        grid_1.addWidget(bouton_affichage_tab_4, 0, 1)
        groupe_1.setLayout(grid_1)
        layout = QGridLayout()
        layout.addWidget(groupe_1, 0, 0)
        self.setLayout(layout)
        
        # Signal
        bouton_affichage_tab_4.clicked.connect(self.show_tab_4)
        
    def show_tab_4(self) :
        """ """
        
        from . import CLASSE_Main
        
        cp = CLASSE_Main()
        
        print("dir(cp)", dir(cp))
        #cp.tab_widget.setCurrentIndex(3)
        print("cp.get_tabwidget(), type(cp.get_tabwidget())", cp.get_tabwidget(), type(cp.get_tabwidget()))
        # --------------------------------------
        cp.get_tabwidget().setCurrentIndex(3)
        # --------------------------------------
        for cle, valeur in cp.__dict__.items():
            if cle == 'tab_widget' :
                print("valeur :", type(valeur))
                # --------------------------------------
                valeur.setCurrentIndex(3)
                # --------------------------------------


class CLASSE_2(QWidget) :
    """ """
    
    def __init__(self, parent):
        super(CLASSE_2, self).__init__(parent)

        label_classe_2 = QLabel("I'm class 2 label")
        groupe_1 = QGroupBox()
        grid_1 = QGridLayout()
        grid_1.addWidget(label_classe_2, 0, 0)
        groupe_1.setLayout(grid_1)
        layout = QGridLayout()
        layout.addWidget(groupe_1, 0, 0)
        self.setLayout(layout)


class CLASSE_3(QWidget) :
    """ """
    
    def __init__(self, parent=None):
        super(CLASSE_3, self).__init__(parent)

        label_classe_3 = QLabel("I'm class 3 label")
        groupe_1 = QGroupBox()
        grid_1 = QGridLayout()
        grid_1.addWidget(label_classe_3, 0, 0)
        groupe_1.setLayout(grid_1)
        layout = QGridLayout()
        layout.addWidget(groupe_1, 0, 0)
        self.setLayout(layout)


class CLASSE_4(QWidget) :
    """ """
    def __init__(self, parent):
        super(CLASSE_4, self).__init__(parent)

        label_classe_4 = QLabel("I'm class 4 label")
        groupe_1 = QGroupBox()
        grid_1 = QGridLayout()
        grid_1.addWidget(label_classe_4, 0, 0)
        groupe_1.setLayout(grid_1)
        layout = QGridLayout()
        layout.addWidget(groupe_1, 0, 0)
        self.setLayout(layout)


class CLASSE_5(QWidget) :
    """ """
    
    def __init__(self, parent=None):
        super(CLASSE_5, self).__init__(parent)

        label_classe_5 = QLabel("I'm class 5 label")
        groupe_1 = QGroupBox()
        grid_1 = QGridLayout()
        grid_1.addWidget(label_classe_5, 0, 0)
        groupe_1.setLayout(grid_1)
        layout = QGridLayout()
        layout.addWidget(groupe_1, 0, 0)
        self.setLayout(layout)

        
class CLASSE_6(QWidget) :
    """ """
    
    def __init__(self, parent):
        super(CLASSE_6, self).__init__(parent)

        label_classe_6 = QLabel("I'm class 6 label")
        groupe_1 = QGroupBox()
        grid_1 = QGridLayout()
        grid_1.addWidget(label_classe_6, 0, 0)
        groupe_1.setLayout(grid_1)
        layout = QGridLayout()
        layout.addWidget(groupe_1, 0, 0)
        self.setLayout(layout)


class CLASSE_Main(QMainWindow):
    """ Main class """
    
    def __init__(self):
        super(CLASSE_Main, self).__init__()

        self.setWindowTitle('Help me please !')

        self.setGeometry(20, 40, 600, 400)
        self.setMinimumSize(600, 460)

        self.tab_widget = QTabWidget()

        self.win_widget_1 = CLASSE_1(self)
        self.win_widget_2 = CLASSE_2(self)
        self.win_widget_3 = CLASSE_3(self)
        self.win_widget_4 = CLASSE_4(self)
        self.win_widget_5 = CLASSE_5(self)
        self.win_widget_6 = CLASSE_6(self)
        
        widget = QWidget()

        layout = QVBoxLayout(widget)
        
        self.tab_widget.addTab(self.win_widget_1, "Tab 1")
        self.tab_widget.addTab(self.win_widget_2, "Tab 2")
        self.tab_widget.addTab(self.win_widget_3, "Tab 3")
        self.tab_widget.addTab(self.win_widget_4, "Tab 4")
        self.tab_widget.addTab(self.win_widget_5, "Tab 5")
        self.tab_widget.addTab(self.win_widget_6, "Tab 6")

        self.tab_widget.setStyleSheet("""QTabWidget::tab-bar {alignment: center;}""")

        layout.addWidget(self.tab_widget)

        self.setCentralWidget(widget)
        
    def get_tabwidget(self) :
        """ """
        return self.tab_widget


if __name__ == '__main__':
    app = QApplication(sys.argv)
    ex = CLASSE_Main()
    ex.show()
    sys.exit(app.exec_())

Solution

Explanation:

It is not necessary to import a class defined in the same script so remove from . import CLASSE_Main.

On the other hand, although the code no longer throws the exception, you have another problem: "cp" is not "ex" since they are 2 different objects.

Solution:

One possible solution is to create a signal that sends the information of the new index that you want to show in the QTabWidget and link that signal to the setCurrentIndex method of the correct QTabWidget:

from PyQt5.QtCore import pyqtSignal

class CLASSE_1(QWidget):
    customSignal = pyqtSignal(int)

    # ...

    def show_tab_4(self):
        self.customSignal.emit(3)

class CLASSE_Main(QMainWindow):
    """ Main class """

    def __init__(self):
        super(CLASSE_Main, self).__init__()

        # ...

        self.setCentralWidget(widget)

        self.win_widget_1.customSignal.connect(self.tab_widget.setCurrentIndex)

Answered By - eyllanesc