將 tkinter 變量傳遞給另一個函數

Question

我似乎很難理解函數如何相互傳遞信息。 我自學 Python 有一段時間了，但我總是碰壁。

在下面的示例中， create_list()函數對playerlist或tkinter小部件playerOption 一無所知。 我真的不知道如何克服這個問題！

非常感謝所有幫助。 今天已經工作了大約 6 個小時，但我無處可去！ 提前致謝。

from tkinter import *


def create_list(surname):

    table = r'c:\directory\players.dbf'

    with table:
        # Create an index of column/s
        index = table.create_index(lambda rec: (rec.name))

        # Creates a list of matching values
        matches = index.search(match=(surname,), partial=True)

        # Populate playerOption Menu with playerlist.
        playerlist = []
        for item in matches:
            playerlist.append([item[4], item[2], item[1]])

        m = playerOption.children['menu']
        m.delete(0, END)
        for line in playerlist:
            m.add_command(label=line,command=lambda v=var,l=line:v.set(l))


def main():

    master = Tk()
    master.geometry('{}x{}'.format(400, 125))
    master.title('Assign a Player to a Team')

    entry = Entry(master, width = 50)
    entry.grid(row = 0, column = 0, columnspan = 5)

    def get_surname():

        surname = entry.get()

        create_list(surname)

    surname_button = Button(master, text='Go', command=get_surname)
    surname_button.grid(row = 0, column = 7, sticky = W)

    # Menu for player choosing.
    var = StringVar(master)

    playerlist = ['']
    playerOption = OptionMenu(master, var, *playerlist)
    playerOption.grid(row = 1, column = 1, columnspan = 4, sticky = EW)

    mainloop()


main()

Answer 1

playlist是在main創建的局部變量。 您必須創建global變量才能在另一個函數中使用它。

# create global variable 

playlist = ['']
#playlist = None


def create_list(surname):
    # inform function `create_list` to use global variable `playlist`
    global playlist

    # assign empty list to global variable - not to create local variable
    # because there is `global playlist`
    playerlist = []

    for item in matches:
        # append element to global variable 
        # (it doesn't need `global playlist`)
        playerlist.append([item[4], item[2], item[1]])



def main():
    # inform function `main` to use global variable `playlist`
    global playlist


    # assign list [''] to global variable - not to create local variable
    # because there is `global playlist`
    playlist = ['']

    # use global variable 
    # (it doesn't need `global playlist`)
    playerOption = OptionMenu(master, var, *playerlist)

如果您不想在該功能中為playlist分配新列表，則可以在功能中跳過global playlist列表。