Kivy计算器应用

Question

Trying to build a simple calculator with the kivy framework.

This is in my main.py file

class Calculator(AnchorLayout):

inputs = ObjectProperty(None)

def backward(self, express):
    if express:
        self.display.text = express[:-1]

def show(self):
    self.inputs.text = self.inputs.text + self.text

def calculate(self, express):
    if not express: return

    try:
        self.display.text = str( eval(express) )
    except Exception:
        self.display.text = 'error'


class CalculatorApp(App):
    def build(self):
        return Calculator()


CalculatorApp().run()

and in my kivy file instead of doing:

Button:
            text: '9'
            on_press: input_string.text += self.text

i want to use the show function that i defined in my main.py

Button:    
            text: '7'
            on_press: root.show()           

but i get an AttributeError: Calculator object has no attribute 'text'

Answer 1

You have this line in the show method of Calculator :

self.inputs.text = self.inputs.text + self.text

This refers to self.text, but the code you've given never sets this attribute for the Calculator, therefore you get the given error: Calculator object has no attribute 'text'