Setting global variables between classes with tKinter

Question

I am currently struggling to use input derived from another class (which uses tkinter) to alter outputs in a different class. This is my code:

#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

furas · Accepted Answer · 2016-10-04 05:33:51Z

1

global doesn't create variable - it only informs function/method to use global variable instead of local variable. First you have to create this variable before classes.

BTW: if you use classes so why don't you use in first class

self.cs_hobby = 'sumo_wrestler'

and in ClassConfirmation

sone_object_name.cs_hobby

or

app = ClassConfirmation(toplevel, 'sumo_wrestler')


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

        # here use cs_hobby

EDIT:

First: global cs_hobby doesn't create global variable. It only inform function to use global cs_hobby instead of local cs_hobby

to work with global you need

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

to work without global variable you need

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

edited Oct 4, 2016 at 5:33

answered Oct 1, 2016 at 7:49

furas

149k12 gold badges121 silver badges171 bronze badges

Sign up to request clarification or add additional context in comments.

4 Comments

Barry Doneas Over a year ago

I don't understand what this means and how this works, can you explain it please?

furas Over a year ago

see new text in answer

Barry Doneas Over a year ago

so when you put words in the brackets after def, does that import variables from outside the class/def?

furas Over a year ago

when you have def fun(arg1, arg2) and use fun(123, "Hello") then fun creates local variables arg1 and arg2 and assigns arg1=123 and arg2="Hello". It doesn't mean that fun import external variables arg1 and arg2. When you use fun(global_variable_1, global_variable_2) then fun creates local arg1 arg2 again and assigns arg1=global_variable_1, arg2=global_variable_2`.

Collectives™ on Stack Overflow

Setting global variables between classes with tKinter

1 Answer 1

4 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

4 Comments

Your Answer

Sign up or log in

Post as a guest

Related