Calling a python kivy callback every 30 seconds while Switch is active?

Question

I'm building an app in python kivy.

I've got a switch widget ( switch1 ), and when it's active I want to print ' Hello world' every 30 seconds .

In my attempt below I first define a callback ( switch1_callback ) that prints ' Hello world '. Then I define another callback ( timely_switch1_callback ) with Clock.schedule_interval() that calls switch1_callback . timely_switch1_callback is bound to switch1 .

I keep getting an error message (TypeError: switch1_callback() takes 1 positional argument but 2 were given) .

Thanks for any help!

from kivy.app import App
from kivy.lang import Builder
from kivy.uix.floatlayout import FloatLayout
from kivy.graphics import Rectangle, Color
from kivy.clock import Clock

kv = '''
<PrettySwitch>:
size_hint: None, None
size: 300, 300
canvas:
    Color:
        rgba: 0, 0, 1, 1    
    Rectangle:
        size: self.size  
        pos: self.pos
Switch:
    id: switch1                 
    pos: 150, 150
    size_hint: None, None
    size: 100, 50
    active: True   
    on_active: root.timely_switch1_callback()
    
'''
class PrettySwitch(FloatLayout):

    def switch1_callback(self):
        print('Hello world')

    def timely_switch1_callback(self):
        Clock.schedule_interval(self.switch1_callback, 30)
    
class SwitchApp(App):
    def build(self):
        Builder.load_string(kv)
        return PrettySwitch()

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

Answer 1

Just change your definition of switch1_callback() to take 2 arguments:

def switch1_callback(self, dt):

The dt argument is added by Clock.schedule_interval() .