TypeError:run() 缺少 1 个必需的位置参数：'self'

Question

I wrote a simple program in pycharm on Windows, then it ran. In order to get the apk file, I installed ubuntu on a virtual machine. Then I installed pip, paycharm, kivy. Qivy installed through the terminal according to the instructions with their site. I typed the code and got an error:run() missing 1 required positional argument: 'self'. I tried to google but I couldn't find anything really.

from kivy.app import App
from kivy.uix.floatlayout import FloatLayout

class Container(FloatLayout):
    pass

class MyApp(App):
    def build(self):

        return Container()


if __name__=='__main__':
    MyApp().run()

in.kv file

<Container>:
    Button:
        background_normal: ''
        background_color: 0.5, 0, 1, .5
        size_hint: 0.3, 0.3
        pos_hint: {'center_x' : 0.5 , 'center_y':0.5}
        text:'Push'
        color: 0,1,0.5,1
        on_release:
            self.text = 'on release'

full error traceback

Answer 1

the.kv file does not support multi-line entries so far as I know. The method on_release needs to reference a function and you would normally put that in the widget (root.your_function) or app (app.your_function). I changed the answer to use build_string only for convenience; it is a good idea to use a separate.kv file in your application as you did.

from kivy.app import App
from kivy.uix.floatlayout import FloatLayout
from kivy.lang import Builder

Builder.load_string('''
<Container>:
    Button:
        background_normal: ''
        background_color: 0.5, 0, 1, .5
        size_hint: 0.3, 0.3
        pos_hint: {'center_x' : 0.5 , 'center_y':0.5}
        text:'Push'
        color: 0,1,0.5,1
        # self argument here will be the button object
        on_release: app.button_callback(self)
''')


class Container(FloatLayout):
    pass


class MyApp(App):

    def button_callback(self, my_button):
        print(my_button.text)
        self.count += 1
        my_button.text = f"on_release {self.count}"

    def build(self):
        self.count = 0
        return Container()


if __name__=='__main__':
    MyApp().run()