how can I pass parameters in a lambda expression? Tkinter

Question

I have a key pad in tkinter made of buttons, when clicked they add their number to a string "Amount Entered" which will be converted to a float at the end.

AmountEntered = ""

Number = tk.Button(self, text = "7", command = lambda AmountEntered: AmountEntered + "7")
Number.grid(row = 0, column = 0, sticky='nsew')

however when clicked, I get the error TypeError: () missing 1 required positional argument: 'AmountEntered'

I thought that the first AmountEntered would be the parameter, what does this refer to?

Your question is "pass parameters ...": Where is your function, you want to pass the parameter? Edit your question accordingly. — stovfl
– stovfl, Commented Dec 2, 2019 at 14:31

chepner · Accepted Answer · 2019-12-02 14:16:15Z

1

The problem isn't with the lambda expression; the problem in the assumption that the callback function will be called with an argument. It won't be. AmountEntered really is a global variable, so all you need is

Number = tk.Button(self, text="7", command=lambda: AmountEntered + "7")

answered Dec 2, 2019 at 14:16

chepner

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