Demo/tkinter/matt/entry-with-shared-variable.py

   1 from Tkinter import *
   2 import string
   3
   4 # This program  shows how to make a typein box shadow a program variable.
   5
   6 class App(Frame):
   7     def __init__(self, master=None):
   8         Frame.__init__(self, master)
   9         self.pack()
  10
  11         self.entrythingy = Entry(self)
  12         self.entrythingy.pack()
  13
  14         self.button = Button(self, text="Uppercase The Entry",
  15                              command=self.upper)
  16         self.button.pack()
  17
  18         # here we have the text in the entry widget tied to a variable.
  19         # changes in the variable are echoed in the widget and vice versa.
  20         # Very handy.
  21         # there are other Variable types. See Tkinter.py for all
  22         # the other variable types that can be shadowed
  23         self.contents = StringVar()
  24         self.contents.set("this is a variable")
  25         self.entrythingy.config(textvariable=self.contents)
  26
  27         # and here we get a callback when the user hits return. we could
  28         # make the key that triggers the callback anything we wanted to.
  29         # other typical options might be <Key-Tab> or <Key> (for anything)
  30         self.entrythingy.bind('<Key-Return>', self.print_contents)
  31
  32     def upper(self):
  33         # notice here, we don't actually refer to the entry box.
  34         # we just operate on the string variable and we
  35         # because it's being looked at by the entry widget, changing
  36         # the variable changes the entry widget display automatically.
  37         # the strange get/set operators are clunky, true...
  38         str = string.upper(self.contents.get())
  39         self.contents.set(str)
  40
  41     def print_contents(self, event):
  42         print "hi. contents of entry is now ---->", self.contents.get()
  43
  44 root = App()
  45 root.master.title("Foo")
  46 root.mainloop()
  47