Python Kivy 覆盖方法

Question

我尽量减少了示例，但它看起来很空，之后问题也不完全一样。

我想我误解了关于 class 变量和实例变量的事情，但是 Kivy 在这方面没有帮助我：我们创建了很多 class 但从未实例化它们！

当然我希望出现“Screenx 实例已覆盖问题”消息，而我只看到“未覆盖”。

calendrier.py

from kivy.properties import StringProperty
from kivy.app import App
from kivy.lang import Builder
from kivy.uix.screenmanager import ScreenManager, Screen
from kivy.clock import Clock

class Menu(Screen):
    pass

class CalculGenerique(Screen):
    question = StringProperty()

    def __init__(self, **kwargs):
        super(CalculGenerique, self).__init__(**kwargs)
        Clock.schedule_once(self.late_init, 0)

    def late_init(self, *largs):
        self.renew_question()

    def renew_question(self):
        self.question = "Not overwritten"

class Screen1(CalculGenerique):
    def renew_question(self):
        self.question = "Screen1 instance has overwritten question"

class Screen2(CalculGenerique):
    def renew_question(self):
        self.question = "Screen2 instance has overwritten question"

class MyScreenManager(ScreenManager):
    pass

class CalendarApp(App):

    def build(self):
        root_widget = Builder.load_file("calendrier.kv")
        return root_widget

if __name__ == "__main__":
    app = CalendarApp()
    app.run()

calendrier.kv

#:import App kivy.app.App

MyScreenManager:
    Menu:
    CalculGenerique:
        name: 'Screen1'
    CalculGenerique:
        name: 'Screen2'

<Menu>:
    name: 'Menu'
    BoxLayout:
        orientation: 'vertical'

        Button:
            text: 'Screen1'
            on_press : app.root.current = 'Screen1'

        Button:
            text: 'Screen2'
            on_press : app.root.current = 'Screen2'

        Button:
            text: 'Quitter l app'
            on_press : App.get_running_app().stop()

<CalculGenerique@Screen>:
    BoxLayout:
        orientation: 'vertical'
        Button:
            text: 'Back to Menu'
            on_press : app.root.current = 'Menu'
        Label:
            text: root.question

Answer 1

您的 'kv' 规则：

MyScreenManager:
    Menu:
    CalculGenerique:
        name: 'Screen1'
    CalculGenerique:
        name: 'Screen2'

创建 CalculGenerique class 的两个实例，但没有 Screen1 或 Screen2 的实例。我认为您只需要将该规则更改为：

MyScreenManager:
    Menu:
    Screen1:
        name: 'Screen1'
    Screen2:
        name: 'Screen2'

一个Screen的name属性只是用来标识Screen，并没有指定class.

Python Kivy 覆盖方法

Python Kivy Overwritting method

python

overriding

kivy