Marco Soldavini wrote: > Hello, > probably this is a very naive question, but I've read some stuff on > Tkinter and its infinite loop. > > Then about how can i bind actions to elements, for example buttons. > > What if I want to run another loop beside the graphical interface in > the same python script?
I usually adapt http://effbot.org/zone/tkinter-threads.htm > For example a state machine with a var state which can have some > discrete string values (like RUNNING, STOPPED, PAUSED, ABORTED, IDLE) > and a text element on the gui that reports that state. > > So a button cause a transition > the python loop (not the gui loop) > detects the transition and changes the state var value > the gui > refresh its value on screen. > > I wrote some code to try it without threading but it does not give the > expected result as it seems the button update status action is already > triggered. I am missing some basic point here Indeed your problem has nothing to do with threads. > > from Tkinter import * > > state = "STOPPED" > > root = Tk() > > myContainer1 = Frame(root) > myContainer1.pack() > label1=Label(myContainer1, text=state, font = "Helvetica 16 bold italic") > label1.pack() > > def change(new_state): > label1.config(text=new_state) > > button1 = Button(myContainer1, text="START") > button1.bind("<Button-1>", change("START")) In the line above you invoke the change function and bind its result (None) to the button1 widget's <Button-1> event. Instead you should pass a function that will be invoked by Tkinter when the button is pressed: def start(event): change("START") button1.bind("<Button-1>", start) You can define simple functions inline, so button1.bind("<Button-1>", lambda event: change("START")) would also work. However, the usual way to bind actions to Button widgets is to pass the callback function as the command argument to the constructor: button = Button(container, command=your_func_that_takes_no_args) With that approach your script will become from Tkinter import * def change(new_state): label1.config(text=new_state) def start(): change("RUNNING") def stop(): change("STOPPED") root = Tk() myContainer1 = Frame(root) myContainer1.pack() label1 = Label(myContainer1, font="Helvetica 16 bold italic") label1.pack() stop() button1 = Button(myContainer1, text="Start", command=start) button1.pack() button2 = Button(myContainer1, text="Stop", command=stop) button2.pack() root.mainloop() _______________________________________________ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
