How can I get the value of 'username' inside the function Login() to use it on another python program?

Question

from Tkinter import *

root = Tk()
root.geometry("230x100")

L1 = Label(root, text="Login page", bg = "blue", fg = "white")
L1.pack(fill = X, ipadx = 5, ipady = 5)

V = StringVar(root, value='Enter username here')
E1 = Entry(root, textvariable=V)
E1.pack(side = LEFT, padx = 5, pady = 5)

def Login():
    username = V.get()
    print "Username is '" + username + "'"

B1 = Button(root, text ="Login" , command = Login)
B1.pack(side = RIGHT, fill = X, pady=5)

mainloop()

I have been trying to get the value of 'username' in the function Login() to use it on another python program.

I have tried setting it as global variable and changing its scope but I am not getting anything.

I need to use the value of 'Username' outside the function Login(). Please provide your insights.

Answer 1

1) Create a python file say ' global_vars.py ' and add this line in it.

#global_vars.py
global_V = ''

2) Import this global_vars.py wherever you want set the variable as below:

#main.py

from Tkinter import *
import global_vars

root = Tk()
root.geometry("230x100")

L1 = Label(root, text="Login page", bg = "blue", fg = "white")
L1.pack(fill = X, ipadx = 5, ipady = 5)

V = StringVar(root, value='Enter username here')
#Set the global variable
global_vars.global_V = V
E1 = Entry(root, textvariable=V)
E1.pack(side = LEFT, padx = 5, pady = 5)

3) Consider you want to use this value in python program present in file " test.py ". Just import global_vars.py and use this variable

#test.py

import global_vars.py

def printUserName():
    print "Username is -", global_vars.global_V

Answer 2

Think about scope for a moment. When your program ends, all memory (meaning variables, objects, etc.) are released. The only 2 ways I can think of to pass something from one program to another is:

1) Write the username value to a file which the next program can read as part of its startup.

2) Have a third "controller" or "launcher" program that runs the program above, takes a return value from that program, then passes that value as a parameter to the next program.

But in any case, you will have to save that value past the scope of the program above.

Answer 3

If you have to python files, one called main.py that contains your main program (I assumed it was a GUI program) and the login.py file that contains the login program.

main.py

from tkinter import Tk, Label
from login import LoginGUI

class mainGUI(Tk):
    def __init__(self):
        Tk.__init__(self)
        Label(self, text="You need to login first",
              bg="blue", fg="white").pack(fill="x", ipadx=5, ipady=5)
        # open login dialog
        login = LoginGUI(self)
        # wait for the user to log in
        self.wait_window(login)
        username = login.getLogin()
        Label(self,
              text="Your username is " + username).pack(fill="x", ipadx=5, ipady=5)
        self.mainloop()


if __name__ == '__main__':
    mainGUI()

login.py

from tkinter import Toplevel, StringVar, Entry, Button, Label

from tkinter import Toplevel, StringVar, Entry, Button, Label

class LoginGUI(Toplevel):
    def __init__(self, master):
        Toplevel.__init__(self, master)
        self.transient(master)
        self.geometry("230x100")
        Label(self, text="Login page",
              bg="blue", fg="white").pack(fill="x", ipadx=5, ipady=5)
        self.username = ""
        self.usernameVar = StringVar(self, value='Enter username here')
        E1 = Entry(self,
                  textvariable=self.usernameVar)
        E1.pack(side="left", padx=5, pady=5)
        Button(self, text="Login",
               command=self.Login).pack(side="right", fill="x", pady=5)
        E1.focus_set()

    def Login(self):
        self.username = self.usernameVar.get()
        self.destroy()

    def getLogin(self):
        return self.username

If your main program have no GUI, replace Toplevel by Tk in login.py and add a self.mainloop at the end of the __init__ method.

Answer 4

您可以使用subprocess启动另一个程序，或者重构另一个程序，以便可以将用户名作为函数的参数传递，并将该程序作为主程序的模块导入。