[FIXED] PyQt5 - encapsulate / make a component reusable - example: QTimer/QLabel implementation outside of parent class

Issue

I implement a label that displays the current time in several of my PyQt5 applications. Here is a MRE:

import sys 
import logging

from PyQt5 import QtWidgets, QtCore, QtGui

__log__ = logging.getLogger()


class App(QtWidgets.QApplication):
    
    def __init__(self, sys_argv):
        super(App, self).__init__(sys_argv)
        self.main_view = MainView()
        self.main_view.show()


class MainView(QtWidgets.QMainWindow):
    def __init__(self):
        super().__init__()
        self.setObjectName("MreUi")
        self.resize(300, 100)
        self.setWindowTitle('MreUi')
        self.label = QtWidgets.QLabel()
        self.setCentralWidget(self.label)
        config_clock(self.label)
        self.start_clocks()
        
    def start_clocks(self):
        timer = QtCore.QTimer(self)
        timer.timeout.connect(self.show_time)  
        timer.start(1000)
        
    def show_time(self):
        current_time = QtCore.QTime.currentTime()
        clock_label_time = current_time.toString('hh:mm:ss')
        self.label.setText(clock_label_time)


def config_clock(label):
    label.setAlignment(QtCore.Qt.AlignCenter)
    font = QtGui.QFont('Arial', 24, QtGui.QFont.Bold)
    label.setFont(font)
        
        
if __name__ == '__main__':
    logging.basicConfig()
    app = App(sys.argv)
    try:
        sys.exit(app.exec_())
    except Exception as e:
        __log__.error('%s', e)

As I implemented a similar clock in several of my PyQt apps, I thought it would be nice to implement it as a component / encapsulate it. First I thought of doing this by calling a config_clock function from any QWidget, and have that function do ~ALL of the work implementing the clock for the specified label. This would avoid having to repeat myself in multiple applications from writing/calling start_clocks and show_time instance methods of MainView. but as I started to code that ...

# from inside my QWidget:
config_clock(self.label)

# this function would live outisde the class, thus reusable by diff Qt apps:
def config_clock(label):
   # start the clock
   # set default font, etc for label
   # instantiate QtCore.QTimer
   # # but that's when I realized I've always passed self to QtCore.QTimer and that maybe encapsulating this isn't as trivial as I thought.

Should I create some kind of ClockLabel() object of my own that gets passed a QtWidget's label and can also be an instance attribute of each QtWidget that might need it? That smells kind of clunky to me. But surely there must be a way to make a 'reusable component' in PyQt, I just don't know how...

I also am not certain if the MainView(QtWidgets.QMainWindow) could rightly be referred to as the 'parent class' if I were to pass it as a parameter to a ClockLabel() class I write or a config_clock function whose signature could look like:

def config_clock(label, parent_qtwidget):
# also feels clunky and not sure if parent would be the right term

Thanks

Solution

With QtWidgets it is normal to specialize widgets by inheritance. Here is an example of how you might rearrange your code to produce a reusable widget:

class ClockLabel(QtWidgets.QLabel):
    def __init__(self, parent=None):
        super().__init__(parent)

        self.setAlignment(QtCore.Qt.AlignCenter)
        font = QtGui.QFont('Arial', 24, QtGui.QFont.Bold)
        self.setFont(font)

        self._timer = QtCore.QTimer(self)
        self._timer.timeout.connect(self._show_time)

    def start(self):
        self._timer.start(1000)

    def stop(self):
        self._timer.stop()

    def _show_time(self):
        current_time = QtCore.QTime.currentTime()
        clock_label_time = current_time.toString('hh:mm:ss')
        self.setText(clock_label_time)

Answered By - Passerby