Question

我写了一个脚本，显示了某些食品被打开多少天。它通过tkinter在LCD上显示。但是，当我添加新项目时，不会添加第7行。一项被覆盖。我的错误在哪里？

#!/usr/bin/python3
import datetime
from tkinter import *


food = {'potatoes': datetime.date(2018, 12, 8),'sausage': datetime.date(2018, 12, 12), 'cream': datetime.date(2018, 12, 13), 'cauliflower': datetime.date(2018, 12, 11), 'ham': datetime.date(2018, 12, 10)}
food_count = len(food.items())



def add():
    food["tomato"] = datetime.date.today()
    food_count = len(food.items())
    show()


def show():    
    for i in range(0, int(food_count)):
        name, date = list(food.items())[i]
        days_open = (datetime.date.today() - date).days
        label_name = Label(master=window, width=width, height=height,
                                          font=("Arial",10),
                                           text = name)
        label_days= Label(master=window, width=width, height=height,
                                          font=("Arial",10),
                                           text = days_open)
        label_name.grid(row=i+1,column=1)
        label_days.grid(row=i+1,column=2)

width = 20
height = 2

window = Tk()
window.geometry('480x320')

button_add = Button(master=window, width=width, height=height,
                text="Add",
                command=add,
                font=("Arial",10))

label_01 = Label(master=window, width=width, height=height,
              font=("Arial",10),
              text = "Lebensmittel")

label_02 = Label(master=window, width=width, height=height,
              font=("Arial",10),
              text = "geöffnet seit")

button_add.grid(row=0,column=0)
label_01.grid(row=0,column=1)
label_02.grid(row=0,column=2)

show()
window.mainloop()

Answer 1

我想我有一个答案：您的代码是：

def add():
    food["tomato"] = datetime.date.today()
    food_count = len(food.items())
    show()


def show():

for i in range(0, int(food_count)):
    name, date = list(food.items())[i]
    days_open = (datetime.date.today() - date).days
    label_name = Label(master=window, width=width, height=height,
                                      font=("Arial",10),
                                       text = name)


    label_days= Label(master=window, width=width, height=height,
                                      font=("Arial",10),
                                       text = days_open)


    label_name.grid(row=i+1,column=1)
    label_days.grid(row=i+1,column=2)

但是在def show（）中，for循环不执行任何操作，因为未在其中定义food_count，因此for lop不执行任何操作，看看是否可行

def add():
    food["tomato"] = datetime.date.today()
    #food_cound moved to def show
    show()


def show():
    food_count = len(food.items())
    for i in range(0, int(food_count)):
        name, date = list(food.items())[i]
        days_open = (datetime.date.today() - date).days
        label_name = Label(master=window, width=width, height=height,
                                          font=("Arial",10),
                                           text = name)


        label_days= Label(master=window, width=width, height=height,
                                          font=("Arial",10),
                                           text = days_open)


        label_name.grid(row=i+1,column=1)
        label_days.grid(row=i+1,column=2)

Answer 2

此代码中的问题是以下行：

food_count = len(food.items())

此行在本地范围内创建一个新变量，但不会在全局范围内更改该变量（请参见local vs global scope）。

要解决此问题，您需要将add函数更改为：

def add():
    global food_count
    food["tomato"] = datetime.date.today()
    food_count = len(food.items())
    show()

这将确保food_count在全局范围内。

向tkinter添加grid.lines不起作用

2 个答案: