Importing error python tkinter

Question

I've been trying to run this simple test just to get the feel of how to import methods from another script, but I have two problems:

1. the whole program runs instead of just importing and calling, the methods, when I need them too.

2. I'm getting this error:

    Traceback (most recent call last): File "C:\\Users\\devilboy 4\\Documents\\Visual Studio 2013\\Projects\\classvariablesOnANewScript\\classvariablesOnANewScript\\classvariablesOnANewScript.py", line 1, in <module> from logInScreen import getUser, getPass 

   ImportError: cannot import name getUser

This is the script I'm importing to:

from logInScreen import getUser, getPass
class hello:

    def show(self):
        usr = getUser()
        ps = getPass()
        str(usr)
        str(ps)

h = hello()
h.show()

This is what's on logInScreen.py :

from tkinter import *
import os
import tkinter.messagebox

#check si lo entrado es correcto
class checkValidation:
    fail = 0
    user = "hi user"
    password = "nice pass"

   #valida el user y el pass
    def fullVali(self, name, passwd):
         if  name == "" or name == " ":
            tkinter.messagebox.showinfo( "Error","Dejo el usuario en blanco")
            self.fail+= 1
        elif name != "UmetSeg":        
            tkinter.messagebox.showinfo( "Error","Usuario incorrecto")
            self.fail+= 1           
        else :
            self.user = name           
            tkinter.messagebox.showinfo( "ok","dude" + name)

        if  passwd == "" or passwd == " ":
            tkinter.messagebox.showinfo( "Error","Dejo la password en blanco")
            self.fail+= 1
        elif passwd != "SegUmet":            
            tkinter.messagebox.showinfo( "Error","Password incorrecto")
            self.fail+= 1            
        else:
            self.password = passwd           
            tkinter.messagebox.showinfo( "ok","dude" + passwd)
            form.destroy()

         #open another py script    
            #os.system("mainPage3.py 1")
            return

 # no deja pasar parametros por command en el boton a menos que se por lambda, so corre       #este metodo para 
 #correr el metodo de validar
    def callVali(self):
        user = usrIn.get()
        self.fullVali(usrIn.get(), passIn.get())
        return

    def getUser(self):
        return self.user

    def getPass(self):
        return self.password



vali = checkValidation()
form = Tk()
form.title("LogIn")
form.geometry("300x320+300+200")

#User txtBox
usrIn = Entry(form, textvariable = None, width = 30)
usrIn.place(x = 60, y = 140)
user = usrIn.get()
#Passwd txtBox
passIn = Entry(form, textvariable = None, width = 30)
passIn.place(x = 60, y = 200)
#Username Label
usrLblVal = StringVar()
usrLblVal.set("User name")
usrLbl = Label(form, textvariable = usrLblVal  )
usrLbl.place(x = 120, y = 115)

#Passwrd label
passLblVal = StringVar()
passLblVal.set("Password")
passLbl = Label(form, textvariable = passLblVal  )
passLbl.place(x = 120, y = 175)


#Login btn
btn = Button(form, text = "Entrar", width = 10, command = vali.callVali)
btn.place(x = 110, y = 250)

form.mainloop()

I hope I got the indentation right, kinda off a pain going through every line and spacing 4 times till it's right. I apologize for the Spanish, just ignore all the comments lol

Answer 1

You are attempting to import methods from within a class in your LogInScreen.py file. The methods getUser and getPass are bound methods that belong to the class checkValidation , You need to instead import the class and make the call on your class instead

from LogInScreen import checkValidation

validation = checkValidation()
validation.getUser()
validation.getPass()

As a simple illustration consider the following example involving two files:

file_to_import_from.py (Analogous to your logInScreen.py )

class MyClass:
    def my_class_bound_method(self):
        print "hello I a method belonging to MyClass"

def my_method_not_belonging_to_a_class():
    print "Hello, I am a method that does not belong to a class"

file_to_import_to.py (Analogous to the script you are importing to)

from file_to_import_from import my_method_not_belonging_to_a_class

my_method_not_belonging_to_a_class()


from file_to_import_from import MyClass

x = MyClass()
x.my_class_bound_method()

from file_to_import_from import my_class_bound_method

my_class_bound_method()

And see Output

Hello, I am a method that does not belong to a class
hello I a method belonging to MyClass

Traceback (most recent call last):
  File "C:\Users\Joe\Desktop\Python\import_test2.py", line 10, in <module>
    from file_to_import_from import my_class_bound_method
ImportError: cannot import name my_class_bound_method

As you can see, the first two calls worked, but the second time the error you are facing arose, this is because the method my_class_bound_method exists as a method within the class MyClass .

EDIT :

In response to your comment, to avoid running the whole file, surround the code in your 'LogInScreen.py' in an if statement which checks if the file being evaluated by the interpreter is the main file being run.

from tkinter import *
import os
import tkinter.messagebox

#check si lo entrado es correcto
class checkValidation:
    # CODE FROM YOUR CLASS OMITTED FOR BREVITY SAKE

# NOTHING BEYOUND THIS IF STATEMENT WILL RUN WHEN THE FILE IS IMPORTED
if __name__ == "__main__":
    vali = checkValidation()
    # MORE CODE OMITTED FOR BREVITY
    form.mainloop()

The if statement I added here checks a special environment variable that python creates when it interprets a file, which is __name__ , when the file is the file that you are directly running: python file_i_am_running.py the variable __name__ is set the the string "__main__" to indicate it is the main method, when it is not the file being run, and maybe one being imported as in your case, the variable is set to the module name, ie file_to_import .

Answer 2

Change to this:

from logInScreen import checkValidation

And then, use:

check = checkValidation()
usr = check.getUser()
ps = check.getPass()