How to call a function using *args from a button in the python file using kivy

Question

I'm trying to get the button to call a function, in the kivy file I could do it with having *args in the brackets. How do I get the funciton to work in the python file.

main.py

from kivy.config import Config
Config.set('input', 'mouse', 'mouse,disable_multitouch')

from kivy.app import App
from kivy.uix.floatlayout import FloatLayout
from kivy.uix.button import Button
from kivy.uix.bubble import Bubble

class MainWidget(FloatLayout):
    clicked = False
    def __init__(self, **kwargs):
        b = Button(text="A")
        b.bind(self.onpressed)
    def onpressed(self, widget, touch):
        if touch.button == 'left':
            print("LEFT")
            if self.clicked:
                self.remove_widget(self.ccp)
                self.clicked = False
        elif touch.button == 'right':
            print("RIGHT")
            if self.clicked:
                self.remove_widget(self.ccp)
            self.ccp = CutCopyPaste()
            self.add_widget(self.ccp)
            self.clicked = True

class CutCopyPaste(Bubble):
    pass

class RightClickApp(App):
    pass

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

rightclick.kv

MainWidget:

<MainWidget>:
    #Button:
    #    text: "A"
    #    on_touch_down: root.onpressed(*args)

<CutCopyPaste>:
    size_hint: (None, None)
    size: (160, 160)
    pos_hint: {'center_x': .5, 'y': .6}
    BubbleButton:
        text: 'Cut'
    BubbleButton:
        text: 'Copy'
    BubbleButton:
        text: 'Paste'

All the ways I've found to do this haven't worked. Please help.

Answer 1

If you want the Button instance and the touch object to be passed to your onpressed() method, then bind it to on_touch_down, which provides those parameters. Like this:

def __init__(self, **kwargs):
    super().__init__(**kwargs)   # added missing call
    b = Button(text="A")
    b.bind(on_touch_down = self.onpressed)
    self.add_widget(b)  # added

Also, you must call the super() __init__() method whenever you over-ride it. And your code was not adding the Button to the MainWidget.