python如何更改全局变量

Question

我想得到某种确认，即上传成功，我的方法定义类似于以下内容。但是，全局变量的值不会改变。请帮忙

global upload_confirm
upload_confirm = False

def confirm_upload():
    upload_confirm = True

def start_new_upload():
    confirm_upload()
    while (upload_confirm != True):
        print "waiting for upload to be true"
        time.sleep(5)
    if (upload_confirm == True):
        print "start Upload"

start_new_upload()

Answer 1

你可以试试这个：

def confirm_upload():
    global upload_confirm
    upload_confirm = True

由于您在本地范围内执行upload_confirm = True，因此Python将其视为局部变量。因此，您的全局变量保持不变。

Answer 2

您需要将global语句放在要访问全局变量的范围内，即：

upload_confirm = False

def confirm_upload():
    global upload_confirm
    upload_confirm = True

Answer 3

在confirm_upload()方法中尝试此操作。

def confirm_upload():
    global upload_confirm #Add this line
    upload_confirm = True

你需要将它声明为全局内部方法，否则它将默认为local。

Answer 4

global语句应该在函数内部。

def confirm_upload():
    global upload_confirm
    upload_confirm = True

否则，upload_confirm = ..将创建一个局部变量。