can two same pieces of code give different results?

October 12, 2023

my first day of learning kivy framework .

the kivy website shows :

import kivy
kivy.require('2.1.0') # replace with your current kivy version !

from kivy.app import App
from kivy.uix.label import Label


class MyApp(App):

    def build(self):
        return Label(text='Hello world')


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

to create an application and it works as expected . followed manually and made a file named first.py and wrote :

import kivy
kivy.require('2.1.0')

from kivy.app import App
from kivy.uix.label import Label

class MyApp(App):
    
    def build(self):
        return Label(text="hello world")
    

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

and this code is showing the error :

 d:/kivlearn/first.py
[INFO   ] [Logger      ] Record log in C:\Users\sahil\.kivy\logs\kivy_23-10-12_25.txt
[INFO   ] [deps        ] Successfully imported "kivy_deps.angle" 0.3.3
[INFO   ] [deps        ] Successfully imported "kivy_deps.glew" 0.3.1
[INFO   ] [deps        ] Successfully imported "kivy_deps.sdl2" 0.6.0
[INFO   ] [Kivy        ] v2.2.1
[INFO   ] [Kivy        ] Installed at "D:\kivlearn\kivy_venv\Lib\site-packages\kivy\__init__.py"
[INFO   ] [Python      ] v3.11.6 (tags/v3.11.6:8b6ee5b, Oct  2 2023, 14:57:12) [MSC v.1935 64 bit (AMD64)]
[INFO   ] [Python      ] Interpreter at "D:\kivlearn\kivy_venv\Scripts\python.exe"
[INFO   ] [Logger      ] Purge log fired. Processing...
[INFO   ] [Logger      ] Purge finished!
[INFO   ] [Factory     ] 190 symbols loaded
[INFO   ] [Image       ] Providers: img_tex, img_dds, img_sdl2, img_pil (img_ffpyplayer ignored)
[INFO   ] [Text        ] Provider: sdl2
 Traceback (most recent call last):
   File "d:\kivlearn\first.py", line 14, in <module>
     MyApp.run()
 TypeError: App.run() missing 1 required positional argument: 'self'
(kivy_venv) PS D:\kivlearn>

is there a difference in both the pieces of code? what to do?

i tried switching back to global installation rather than the environment , but the problem persisted.

>Solution :

The two pieces of code are not the same, note in particular:

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

vs.

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

The first example instantiates MyApp, and then calls run, the second only calls the method on the class object. This also explains why you see the error message that you see (self doesn’t exist in the second context).