Developing a Full Tkinter Object-Oriented Application

Summary: in this tutorial, you’ll learn how to develop a full Tkinter object-oriented application.

You’ll convert the temperature converter application to a new one that uses object-oriented programming approach:

First, define a class called TemperatureConverter. The class has one static method that converts a temperature from Fahrenheit to Celsius:

import tkinter as tk
from tkinter import ttk
from tkinter.messagebox import showerror


class TemperatureConverter:
    @staticmethod
    def fahrenheit_to_celsius(f):
        return (f - 32) * 5 / 9
Code language: Python (python)

Second, define a ConverterFrame class that inherits from the ttk.Frame class. The ConverterFrame class will be responsible for creating widgets and handling events:

class ConverterFrame(ttk.Frame):
    def __init__(self, container):
        super().__init__(container)
        # field options
        options = {'padx': 5, 'pady': 5}

        # temperature label
        self.temperature_label = ttk.Label(self, text='Fahrenheit')
        self.temperature_label.grid(column=0, row=0, sticky=tk.W, **options)

        # temperature entry
        self.temperature = tk.StringVar()
        self.temperature_entry = ttk.Entry(self, textvariable=self.temperature)
        self.temperature_entry.grid(column=1, row=0, **options)
        self.temperature_entry.focus()

        self.convert_button = ttk.Button(self, text='Convert')
        self.convert_button['command'] = self.convert
        self.convert_button.grid(column=2, row=0, sticky=tk.W, **options)

        # result label
        self.result_label = ttk.Label(self)
        self.result_label.grid(row=1, columnspan=3, **options)

        # add padding to the frame and show it
        self.grid(padx=10, pady=10, sticky=tk.NSEW)

    def convert(self):
        """  Handle button click event
        """
        try:
            f = float(self.temperature.get())
            c = TemperatureConverter.fahrenheit_to_celsius(f)
            result = f'{f} Fahrenheit = {c:.2f} Celsius'
            self.result_label.config(text=result)
        except ValueError as error:
            showerror(title='Error', message=error)
Code language: Python (python)

How it works:

• The ConverterFrame needs a container, therefore, its __init__() method has the container argument.
• Inside the __init__() method of the ConverterCFrame class, call the __init__() method of its superclass.
• Assign the widgets to the self object so that you can reference them in other methods of the ConverterFrame class.
• Assign the command option of the convert button to the self.convert method.

Third, define an App class that inherits from the tk.Tk class:

class App(tk.Tk):
    def __init__(self):
        super().__init__()

        self.title('Temperature Converter')
        self.geometry('300x70')
        self.resizable(False, False)Code language: Python (python)

Finally, bootstrap the application from the if __name__ == "__main__" block:

if __name__ == "__main__":
    app = App()
    ConverterFrame(app)
    app.mainloop()
Code language: Python (python)

Put it all together:

import tkinter as tk
from tkinter import ttk
from tkinter.messagebox import showerror


class TemperatureConverter:
    @staticmethod
    def fahrenheit_to_celsius(f):
        return (f - 32) * 5 / 9


class ConverterFrame(ttk.Frame):
    def __init__(self, container):
        super().__init__(container)
        # field options
        options = {'padx': 5, 'pady': 5}

        # temperature label
        self.temperature_label = ttk.Label(self, text='Fahrenheit')
        self.temperature_label.grid(column=0, row=0, sticky=tk.W, **options)

        # temperature entry
        self.temperature = tk.StringVar()
        self.temperature_entry = ttk.Entry(self, textvariable=self.temperature)
        self.temperature_entry.grid(column=1, row=0, **options)
        self.temperature_entry.focus()

        self.convert_button = ttk.Button(self, text='Convert')
        self.convert_button['command'] = self.convert
        self.convert_button.grid(column=2, row=0, sticky=tk.W, **options)

        # result label
        self.result_label = ttk.Label(self)
        self.result_label.grid(row=1, columnspan=3, **options)

        # add padding to the frame and show it
        self.grid(padx=10, pady=10, sticky=tk.NSEW)

    def convert(self):
        """  Handle button click event
        """
        try:
            f = float(self.temperature.get())
            c = TemperatureConverter.fahrenheit_to_celsius(f)
            result = f'{f} Fahrenheit = {c:.2f} Celsius'
            self.result_label.config(text=result)
        except ValueError as error:
            showerror(title='Error', message=error)


class App(tk.Tk):
    def __init__(self):
        super().__init__()

        self.title('Temperature Converter')
        self.geometry('300x70')
        self.resizable(False, False)


if __name__ == "__main__":
    app = App()
    ConverterFrame(app)
    app.mainloop()
Code language: Python (python)

In this tutorial, you have learned how to develop a full object-oriented Tkinter application.