tkinter - Create a Python calculator without Lambda functions?

Question

I'm trying to create a simple calculator using Tkinter to teach children how to make a basic program. I've made one that works using lambda functions but I'm trying to figure out how to make one without lambdas. Could someone help with this? Here's the code I have so far:

# start coding the buttons
button1 = Button(gui, text=' 1 ', fg='black', bg='gray65', 
                command=lambda: press(1), height=1, width=7) 
button1.grid(row=2, column=0) 

button2 = Button(gui, text=' 2 ', fg='black', bg='gray65', 
                command=lambda: press(2), height=1, width=7) 
button2.grid(row=2, column=1) 

button3 = Button(gui, text=' 3 ', fg='black', bg='gray65', 
                command=lambda: press(3), height=1, width=7) 
button3.grid(row=2, column=2) 

button4 = Button(gui, text=' 4 ', fg='black', bg='gray65', 
                command=lambda: press(4), height=1, width=7) 
button4.grid(row=3, column=0) 

button5 = Button(gui, text=' 5 ', fg='black', bg='gray65', 
                command=lambda: press(5), height=1, width=7) 
button5.grid(row=3, column=1) 

button6 = Button(gui, text=' 6 ', fg='black', bg='gray65', 
                command=lambda: press(6), height=1, width=7) 
button6.grid(row=3, column=2) 

button7 = Button(gui, text=' 7 ', fg='black', bg='gray65', 
                command=lambda: press(7), height=1, width=7) 
button7.grid(row=4, column=0) 

button8 = Button(gui, text=' 8 ', fg='black', bg='gray65', 
                command=lambda: press(8), height=1, width=7) 
button8.grid(row=4, column=1) 

button9 = Button(gui, text=' 9 ', fg='black', bg='gray65', 
                command=lambda: press(9), height=1, width=7) 
button9.grid(row=4, column=2) 

button0 = Button(gui, text=' 0 ', fg='black', bg='gray65', 
                command=lambda: press(0), height=1, width=7) 
button0.grid(row=5, column=0) 

plus = Button(gui, text=' + ', fg='black', bg='gray65', 
            command=lambda: press("+"), height=1, width=7) 
plus.grid(row=2, column=3) 

minus = Button(gui, text=' - ', fg='black', bg='gray65', 
            command=lambda: press("-"), height=1, width=7) 
minus.grid(row=3, column=3) 

multiply = Button(gui, text=' * ', fg='black', bg='gray65', 
                command=lambda: press("*"), height=1, width=7) 
multiply.grid(row=4, column=3) 

divide = Button(gui, text=' / ', fg='black', bg='gray65', 
                command=lambda: press("/"), height=1, width=7) 
divide.grid(row=5, column=3)  

Decimal= Button(gui, text='.', fg='black', bg='gray65', 
            command=lambda: press('.'), height=1, width=7) 
Decimal.grid(row=5, column='1')

question from:https://stackoverflow.com/questions/65865910/create-a-python-calculator-without-lambda-functions

Answer 1

Anywhere you use lambda you can instead use def:

button1 = Button(gui, text=' 1 ', fg='black', bg='gray65', 
                command=lambda: press(1), height=1, width=7) 

becomes:

def press_1():
    press(1)

button1 = Button(gui, text=' 1 ', fg='black', bg='gray65', 
                command=press_1, height=1, width=7) 

One way you might make some of this button generation less unwieldy might be to write a function that creates a button which goes with a certain number:

def make_button(num: int) -> Button:
    def press_num():
        press(num)

    return Button(gui, text=f' {num} ', fg='black', bg='gray65', 
                command=press_num, height=1, width=7)

and then you can do:

button1 = make_button(1)
button2 = make_button(2)

etc. You could also take this a bit further by building some parts of the grid inside a nested loop, e.g.:

for row in range(3):
    for col in range(3):
        button = make_button(row * 3 + col + 1)
        button.grid(row=row+2, column=col)