tkinter BMI计算器

import tkinter as tk
import tkinter as ttk
from tkinter import messagebox


class BIMView(tk.Frame):
    def __init__(self, parent, *args, **kwargs):
        super().__init__(parent, *args, **kwargs)
        self.body_weight = tk.DoubleVar()
        self.height = tk.DoubleVar()
        self.bmi = tk.StringVar()

        lbl_body_weight = ttk.Label(self, text="体重(kg):")
        entry_body_weight = ttk.Entry(self, textvariable=self.body_weight)
        lbl_height = ttk.Label(self, text="身高(m):")
        entry_body = ttk.Entry(self, textvariable=self.height)
        btn_claculate = ttk.Button(self, text="计算", command=self.on_calculate)
        lbl_bmi = ttk.Label(self, textvariable=self.bmi, font=("Microsoft Yahei", 64), wraplength=480)

        lbl_body_weight.grid(row=0, column=0, sticky=tk.W)
        entry_body_weight.grid(row=0, column=1, sticky=(tk.W + tk.E))
        lbl_height.grid(row=0, column=2, sticky=(tk.W + tk.E))
        entry_body.grid(row=0, column=3, sticky=(tk.W + tk.E))
        btn_claculate.grid(row=0, column=4, sticky=tk.E)
        lbl_bmi.grid(row=1, column=0, columnspan=5)
        self.columnconfigure(1,weight=1)
        self.columnconfigure(3,weight=1)
    def on_calculate(self):
        try:
            bmi = self.body_weight.get() / (self.height.get() ** 2)
            print(bmi)
            self.bmi.set(f"{bmi:.1f}")
        except Exception as e:
            print(e)
            messagebox.showinfo(title="%s "%str(e),message=str(e))


class BMIApplication(tk.Tk):
    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self.title("BMI 计算器")
        self.geometry("640x180")
        self.resizable(width=False, height=False)
        BIMView(self).grid(sticky=(tk.E + tk.N + tk.W + tk.S))
        self.columnconfigure(0,weight=1)

if __name__ == "__main__":
    app = BMIApplication()
    app.mainloop()