Tkinter calculator with memo of operations

In this version of the mini-calculator seen in the latest post we added a twist… the reminder of the operations made in a listbox. Next post we will add the chance to save the list of operations… how cool is this?

import tkinter as tk

# This class inherit from Frame
class App(tk.Frame):
    def __init__(self):
        tk.Frame.__init__(self)
        self.option_add("*Font", "arial 20 bold")
        self.pack(expand=tk.YES, fill=tk.BOTH)
        self.master.title("Calculator")
        # the widgets: display, clear button...
        self._display()
        self.list_of_ops()

    def _display(self):
        display = tk.StringVar()
        entry = tk.Entry(
            self,
            relief=tk.FLAT,
            textvariable=display,
            justify='right',
            bd=15,
            bg='orange')
        entry.pack(side=tk.TOP)
        entry.focus()
        self.master.bind("<Return>", lambda x: self.calc(display))
        self.master.bind("<Escape>", lambda x: display.set(""))

    def list_of_ops(self):
        self.listbox = tk.Listbox(self)
        self.listbox.pack()


    def calc(self, display):
        try:
            ris = eval(display.get())
            if str(display.get()) == str(ris):
                display.set("")
            else:
                self.listbox.insert(tk.END, display.get() + "=" + str(ris))
                display.set(ris)
        except NameError as e:
            display.set("ERR: press ESC")


if __name__ == '__main__':
    App().mainloop()

Put an icon in the window

If you want to put and icon (a png in this case) you can add this code to the code above, in the def __init__ method, after giving the title to the window:

        self.master.title("Calculator")
        self.master.tk.call('wm', 'iconphoto', self.master._w, tk.PhotoImage(file='calculator.png'))

The result will be this, putting this image, for example, in the same folder of the python script

download the image

In the next episode:

– dark mode

– delete items form the list

– save a list of operations with a name in a text file

– memorize some results in a list to sum them later

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