TrayIcon inherit QSystemTrayIcon, why can't call show() directly after init TrayIcon

[ideaplus]

I write a class TrayIcon inherit QSystemTrayIcon, why I can't call show() directly after init TrayIcon? TrayIcon().show()



# It works:
# my_tray_icon = TrayIcon(my_widget)
# my_tray_icon.show()

# But why doesn't this work? The icon does not appear in the system tray.
TrayIcon(my_widget).show()




import sys

from PySide2.QtGui import QIcon
from PySide2.QtWidgets import QSystemTrayIcon, QAction, QMenu, QApplication, QWidget, qApp


class TrayIcon(QSystemTrayIcon):
def __init__(self, app):
super().__init__()
self.app = app
self.setIcon(QIcon('icon.png'))
self.activated.connect(self.icon_activated)
self.tray_menu = QMenu(QApplication.desktop())
self.show_action = QAction('&show')
self.quit_action = QAction('&exit')
self.show_action.triggered.connect(app.show)
self.quit_action.triggered.connect(qApp.quit)
self.tray_menu.addAction(self.show_action)
self.tray_menu.addAction(self.quit_action)
self.setContextMenu(self.tray_menu)

def icon_activated(self, reason):
if reason in (QSystemTrayIcon.Trigger, QSystemTrayIcon.DoubleClick):
self.app.show()
# for Windows
self.app.activateWindow()
# for macOS
self.app.raise_()


def main():
app = QApplication(sys.argv)
app.setQuitOnLastWindowClosed(False)
my_widget = QWidget()

# It works:
# my_tray_icon = TrayIcon(my_widget)
# my_tray_icon.show()

# But why doesn't this work?
TrayIcon(my_widget).show()

sys.exit(app.exec_())


if __name__ == '__main__':
main()