无法在验证命令中将条目作为参数传递

Question

I'm usign Python 3.x with Tkinter; I would like to check that the value of a tkinter.Entry is a number by calling a function called "is_valid_entry" and passing all args via validatecommand. I would like to use the same function for other entries too. The problem is that inside is_valid_entry I can't clean the entry text with self.delete(0,END) because self is seen as str instead of tkinter.Entry. I hope I made it understandable, thanks for the help!

Here's the code:

from tkinter import *
from tkinter import ttk
from tkinter import filedialog as fd

import tkinter as tk

window = tk.Tk()

window.geometry("600x600")

window.title("Hello Stackoverflow")

window.resizable(False,False)

def isfloat(value):
    try:
        float(value)
        return True
    except ValueError:
        return False

def is_valid_entry(self,value):
    if (value.isnumeric() or isfloat(value)):        
        return True
    else:
        tk.messagebox.showerror(title="Error!", message="Value must be a number!")
        print(type(self))

        self.delete(0,END) # I'd like to clean the entry text but self is type string now not type tkinter.Entry 

        return False

e2=tk.Entry(window,width=20)
e2.grid(row=6,column=2,padx=5)

print(type(e2))
okayCommand = e2.register(is_valid_entry)

e2.config(validate='focusout',validatecommand=(okayCommand,e2,'%P'))

if __name__ == "__main__":
    window.mainloop()

I tried to use a function to check if an entry text is a valid number. I registered the function and configured the entry to call this function in case of 'focusout' via validatecommand. I would like to pass the entry as well (self) as args of validatecommand so that when the function is executed, in case of invalid number, the text in the entry is cleared. The entry param inside the function is seen as a str instead of a tkinter.Entry.

Answer 1

A workaround is to store the widgets in a dictionary with a string key and pass that key in the config setting.

def is_valid_entry(value, widgetname):
    if (value.isnumeric() or isfloat(value)):        
        return True
    else:
        tk.messagebox.showerror(title="Error!", message="Value must be a number!")
        
        mywidgets[widgetname].delete(0,END) 

        return False

e2=tk.Entry(window,width=20)
e2.grid(row=6,column=2,padx=5)

mywidgets = dict()
mywidgets["e2"] = e2

print(type(e2))
okayCommand = e2.register(is_valid_entry)

e2.config(validate='focusout',validatecommand=(okayCommand,'%P','e2'))

Answer 2

The problem is that inside is_valid_entry I can't clean the entry text with self.delete(0,END)

self.delete(0,END)

to:

e2.delete(0,END)