使用tKinter在类之间设置全局变量

Question

我目前正在努力使用从另一个类（使用tkinter）派生的输入来改变另一个类中的输出。这是我的代码：

#there are many of these defs, this is just one i used as an example

    def command_ssumowrestler(self):
        self.master.withdraw()
        toplevel = tk.Toplevel(self.master)
        toplevel.geometry("30x70")
        app=ClassConfirmation(toplevel)
        global cs_hobby
        cs_hobby = 'sumo_wrestler'

class ClassConfirmation:
    def __init__ (self, master):
        self.master = master
        self.frame = tk.Frame(self.master)
        confirmclass_label = tk.Label(master, width = 20, fg = 'blue',text= "Do You Wish to Proceed as:")
        confirmclass_label.pack()

#here i use the variable defined and set globally in the previously block, which always leaves me with an error saying cs_hobby is not defined 

        classdescription_label = tk.Label(master, width =50, text='test ' + cs_hobby + ' hello')
        classdescription_label.pack()
        self.confirmclassButton = tk.Button(self.frame, text = 'Confirm', width = 20, command = self.close_windows)
        self.confirmclassButton.pack()
        self.frame.pack()
    def close_windows (self):
        self.master.withdraw()
        app=dragonrealmP1
#this just opens a different class

Answer 1

global不会创建变量 - 它只会通知函数/方法使用全局变量而不是局部变量。首先，您必须在类之前创建此变量。

顺便说一句：如果你使用课程，那你为什么不在头等课程中使用

self.cs_hobby = 'sumo_wrestler'

并在ClassConfirmation

sone_object_name.cs_hobby 

或

app = ClassConfirmation(toplevel, 'sumo_wrestler')


class ClassConfirmation:
    def __init__ (self, master, cs_hobby):

        # here use cs_hobby 

修改

首先：global cs_hobby不创建全局变量。它仅通知函数使用全局cs_hobby而不是本地cs_hobby

使用您需要的global

cs_hobby = ""   # create global variable (outside classes)


def command_ssumowrestler(self):
    global cs_hobby  # inform function to use global variable

    # rest 

    cs_hobby = 'sumo_wrestler' # set value in global variable

    app = ClassConfirmation(toplevel)


class ClassConfirmation:
    def __init__ (self, master):
        global cs_hobby    # inform function to use global variable

        # rest 

        print(cs_hobby)    # get value from global variable
        cs_hobby = 'tenis' # set value in global variable

在没有全局变量的情况下工作

def command_ssumowrestler(self):
     self.cs_hobby = 'sumo_wrestler' # create local variable

     app = ClassConfirmation(toplevel, self.cs_hobby) # send local value to another class

     self.cs_hobby = app.cs_hobby # receive value from another class


class ClassConfirmation:
    def __init__ (self, master, hobby):
        self.cs_hobby = hobby # create local variable and assign value 

        # rest 

        print(self.cs_hobby)     # use local value
        self.cs_hobby = 'tenis'  # use local value