How would I destroy and recreate my window in PyQt5?

Question

I am practicing multi-file programming and am implementing a simple game of Minesweeper. When the user starts a new game, I create a grid of QPushButtons in the body of my window.

The problem is that whenever a player wants to start a new game of minesweeper, I do not know how to resize my window and reset my grid of QPushButtons so that a new game of minesweeper can be played. My initial approach was to nuke the orignal window and create a brand new one with the following

def newEasyGame(self):
app = QApplication([])
window = minesweeperWindow(10, 10, "easy")
window.show()
app.exec()

I am receiving the error QCoreApplication::exec: the event loop is already running.

EDIT: As requested, here is a more complete code block that describes what I am trying to do in more detail

from PyQt5.QtWidgets import *
from PyQt5.QtGui import *
from PyQt5.QtCore import *

class minesweeperDemoWindow(QMainWindow):    
    def __init__(self, rows, cols, difficulty):
        super(minesweeperDemoWindow, self).__init__()

        #Central widget that is everything is contained within
        widget = QWidget()
        self.setCentralWidget(widget)

        #Vertical layout with a grid of buttons inside of it
        layout = QVBoxLayout()
        widget.setLayout(layout)

        #create a grid of QPushButtons that act as the playing field
        self.playingField = [[0 for x in range(rows)] for y in range(cols)] 

        grid = QGridLayout()
        #for every row and column, add a button
        for r in range(0, rows):
            for c in range(0, cols):
                button = QPushButton()
                button.setFixedSize(30, 30)
                #keep track of each button's position with myRow and myCol
                button.setProperty("myRow", r)
                button.setProperty("myCol", c)
                button.clicked.connect(self.buttonClicked)
                self.playingField[r][c] = button
                grid.addWidget(self.playingField[r][c], r, c)
        layout.addLayout(grid)
        grid.setSpacing(0)

        #How a user is going to start a new game
        menu = self.menuBar().addMenu("&Start new Game")
        newEasy = QAction("Easy", self, shortcut=QKeySequence.New, triggered=self.newEasyGame)

    #when the Easy menu item is selected, destroy the window and create a new easy game
    def newEasyGame(self):
        app = QApplication([])
        window = minesweeperWindow(10, 10, "easy")
        window.show()
        app.exec_()

Answer 1

You do not have to destroy the window. In this case, a possible solution is to eliminate the widget that contains the QGridLayout. To do so, a method must be created that implements the destruction logic if necessary and creates the buttons.

from PyQt5 import QtCore, QtGui, QtWidgets


class MinesweeperDemoWindow(QtWidgets.QMainWindow):
    def __init__(self, parent=None):
        super(MinesweeperDemoWindow, self).__init__(parent)
        levels = [
            (4, 4, "level1"),
            (8, 8, "level2"),
            (16, 16, "level3"),
            (32, 32, "level4"),
        ]
        menu = self.menuBar().addMenu("&Start new Game")
        for r, c, name in levels:
            action = menu.addAction(name)
            action.setData((r, c))
            action.triggered.connect(self.on_triggered)
        r, c, _ = levels[0]
        self.setSize(r, c)

    @QtCore.pyqtSlot()
    def on_triggered(self):
        action = self.sender()
        r, c = action.data()
        self.setSize(r, c)

    def setSize(self, rows, cols):
        # delete the old container
        widget = self.centralWidget()
        if widget is not None:
            widget.deleteLater()
        # create new container
        widget = QtWidgets.QWidget()
        self.setCentralWidget(widget)
        grid = QtWidgets.QGridLayout(widget)
        self.playingField = [[0 for x in range(rows)] for y in range(cols)]
        for r in range(rows):
            for c in range(cols):
                button = QtWidgets.QPushButton()
                button.setFixedSize(30, 30)
                # keep track of each button's position with myRow and myCol
                button.setProperty("myRow", r)
                button.setProperty("myCol", c)
                # button.clicked.connect(self.buttonClicked)
                self.playingField[r][c] = button
                grid.addWidget(button, r, c)
        self.setFixedSize(widget.sizeHint())

    @QtCore.pyqtSlot()
    def buttonClicked(self):
        pass


if __name__ == "__main__":
    import sys

    app = QtWidgets.QApplication(sys.argv)
    w = MinesweeperDemoWindow()
    w.setSize(4, 4)
    w.show()
    sys.exit(app.exec_())