How Can I Execute More A Command Based On The Button That Called It? (classes And Tkinter)

I am teaching myself Python and am currently working on my first project. I am making a calculator application in Python which I am calling Pythulator. I am trying to figure out ho

Solution 1:

This method is highly problematic:

defconcat(self):
    self = str(self)
    numstring.join(self)
    print(numstring)

You have not defined __str__ so str(self) is going to be some funky string. Then numstring.join(self) is a no-operation -- it returns a string you're not assigning to anything at all! So you're always printing the empty numstring you started with.

And -- nowhere are you taking into account which key has been pressed... any keypress triggers exactly the same self.concat call, no info left about "which key was it again?".

functools.partial lets you bind arguments in advance (yes, you could do with a bedraggled lambda, but, you'll be a much happier camper if you forget about lambda's existence...).

So for example one button should be...:

self.numpad_1 = tk.Button(num_frame, text='1',
    command=functools.partial(self.concat, '1'))

and similarly for the others.

Now, the concat method will receive the text corresponding to the button that was clicked and of course it needs to record it somewhere.

I'd recommend eschewing globals and instead starting the __init__ with

self.nums = []

Now concat has an easy life:

def concat(self, digit):
    self.nums.append(digit)
    print(''.join(self.nums))

Incidentally, this lets you far more easily implement key features such as a delete key -- it just needs to drop the last item of the self.nums list (self.nums.pop() will suffice) and it's crucial to let the user correct a typo!

Solution 2:

You can use lambda to make another function that call the original method with additional parameter

In addition to that, you need to declare global variable inside the method. To append a string to another string, you can use += operator.

classNumpad:
    def__init__(self, master):
        num_frame = tk.Frame(master)
        num_frame.pack(side = tk.BOTTOM)
        self.numpad_1 = tk.Button(num_frame, text="1", command=lambda: self.concat('1'))
        self.numpad_1.grid(row=6, column=3)
        self.numpad_2 = tk.Button(num_frame, text="2", command=lambda: self.concat('2'))
        self.numpad_2.grid(row=6, column=4)
        self.numpad_3 = tk.Button(num_frame, text="3", command=lambda: self.concat('3'))
        self.numpad_3.grid(row=6, column=5)
        self.numpad_4 = tk.Button(num_frame, text="4", command=lambda: self.concat('4'))
        self.numpad_4.grid(row=5, column=3)
        self.numpad_5 = tk.Button(num_frame, text="5", command=lambda: self.concat('5'))
        self.numpad_5.grid(row=5, column=4)
        self.numpad_6 = tk.Button(num_frame, text="6", command=lambda: self.concat('6'))
        self.numpad_6.grid(row=5, column=5)
        self.numpad_7 = tk.Button(num_frame, text="7", command=lambda: self.concat('7'))
        self.numpad_7.grid(row=4, column=3)
        self.numpad_8 = tk.Button(num_frame, text="8", command=lambda: self.concat('8'))
        self.numpad_8.grid(row=4, column=4)
        self.numpad_9 = tk.Button(num_frame, text="9", command=lambda: self.concat('9'))
        self.numpad_9.grid(row=4, column=5)
        self.numpad_0 = tk.Button(num_frame, text="0", command=lambda: self.concat('0'))
        self.numpad_0.grid(row=7, column=4)

    defconcat(self, n):
        global numstring
        numstring += n
        print(n, numstring)