from tkinter import *
class EntryStringVarDemo:
    def __init__(self, rootWin):
        
        self.button = Button(rootWin,text="enter",
                             command=self.clicked)
        self.button.pack()


        #A StringVar is a special object that holds strings and
        #can be linked to a GUI element such as an Entry.
        # 1) MAGIC HERE
        self.magicEntryVar = StringVar()

        # 2) Create Entry widget setting magic textvariable!
        self.entry = Entry(rootWin,textvariable=self.magicEntryVar)
        # don't need delete and add text in the Entry widget
        # self.entry.delete(0,END)
        # self.entry.insert(0,"type your name here")
        self.magicEntryVar.set("nice magic!")

        self.entry.pack()

        self.ourRoot = rootWin

    def clicked(self):
        print("Button was clicked!")
        # get text from the Entry widget
        # eText = self.entry.get()

        #3) Simple to get the text from the entry
        eText = self.magicEntryVar.get()
        
        print(eText)

        #4) So easy to set the text for the entry
        self.magicEntryVar.set("wow.  indeed.")

# Create the main root window, instantiate the object, and run main loop!
rootWin = Tk()
app = EntryStringVarDemo(rootWin)
rootWin.mainloop()