How do I create and/or initialize an attribute in Python?

Question

Attempting to make a calculator in Python, and an error shows up twice saying that 'Calculator" has no attribute 'key', as well as an issue with something else. How to I fix these errors?

I attempted to initialize the attribute as best I could, and another error occurred. The errors are on lines 31 and 59

Edit: We good. If you want to try this, Git repo is https://github.com/DerpOKat21/Random-projects

import tkinter as tk

class Calculator:
    def __init__(self, master):
        self.master = master
        master.title("Calculator")

        # Create display
        self.display = tk.Entry(master, width=35, borderwidth=5, font=('Arial', 16))
        self.display.grid(row=0, column=0, columnspan=4, padx=10, pady=10)

        # Create buttons
        button_list = [
            '7', '8', '9', '/',
            '4', '5', '6', '*',
            '1', '2', '3', '-',
            '0', '.', '=', '*'
        ]

        row = 1
        col = 0
        for button_text in button_list:
            button = tk.Button(master, text=button_text, width=5, height=2, font=('Arial', 14),
            command=lambda x=button_text: self.button_click(x))
            button.grid(row=row, column=col, padx=5, pady=5)
            if col == 3:
                col = 0
                row += 1
            else:
                col += 1
            # Bind keyboard keys
            self.master.bind('<Key>', self.key_press)

    def button_click(self, button):
        current = self.display.get()
        if button == 'C':
            self.display.delete(0, tk.END)
        elif button == '=':
            try:
                result = eval(current)
                self.display.delete(0, tk.END)
                self.display.insert(0, str(result))
            except SyntaxError:
                self.display.delete(0, tk.END)
                self.display.insert(0, "Error")
        else:
            self.display.delete(0, tk.END)
            self.display.insert(0, current + button)

    def key_press(self, event):
        key = event.char
        if key in '0123456789+-*/.':
            self.button_click(key)
        elif key == '\r':
            self.button_click('=')
        elif key == '\x1b': # Escape key
            self.display.delete(0, tk.END)

root = tk.Tk()
calculator = Calculator(root)
root.mainloop()

Answer 1

Besides of your code indetention for the functions, your math is and flow cotrol are also of,

as you never change the col number you will stay put at the first button and pile them up, one after another

import tkinter as tk

class Calculator:
    def __init__(self, master):
        self.master = master
        master.title("Calculator")

        # Create display
        self.display = tk.Entry(master, width=35, borderwidth=5, font=('Arial', 16))
        self.display.grid(row=0, column=0, columnspan=4, padx=10, pady=10)

        # Create buttons
        button_list = [
            '7', '8', '9', '/',
            '4', '5', '6', '*',
            '1', '2', '3', '-',
            '0', '.', '=', '*'
        ]

        row = 1
        col = 0
        for button_text in button_list:
            button = tk.Button(master, text=button_text, width=5, height=2, font=('Arial', 14),
            command=lambda x=button_text: self.button_click(x))
            button.grid(row=row, column=col, padx=5, pady=5)
            if col == 3:
                col = 0
                row += 1
            else:
                col += 1
            # Bind keyboard keys
            self.master.bind('<Key>', self.key_press)

    def button_click(self, button):
        current = self.display.get()
        if button == 'C':
            self.display.delete(0, tk.END)
        elif button == '=':
            try:
                result = eval(current)
                self.display.delete(0, tk.END)
                self.display.insert(0, str(result))
            except SyntaxError:
                self.display.delete(0, tk.END)
                self.display.insert(0, "Error")
        else:
            self.display.delete(0, tk.END)
            self.display.insert(0, current + button)

    def key_press(self, event):
        key = event.char
        if key in '0123456789+-*/.':
            self.button_click(key)
        elif key == '\r':
            self.button_click('=')
        elif key == '\x1b': # Escape key
            self.display.delete(0, tk.END)

root = tk.Tk()
calculator = Calculator(root)
root.mainloop()