Tkinter grid_forget在调用时不执行

Question

I am experiencing something I really don't understand. In the program, I pick a data file and then I want to hide the widgets in the window and load the data from file. But everything I tried results in first loading the file and then executing the rest...

def LoadProject():
    old_project = FD.askopenfilename(filetypes=[("Data file","*.dat")], initialdir = "./Projects/")

    if old_project:
        napis.delete(TK.ALL)
        napis.grid_forget()
        button_new.grid_forget()
        button_load.grid_forget()

        data_file = open(old_project,"r")
        for line in data_file:
            line = line.replace("\n","")
            conv = line.split()
            data.append([float(conv[0]),int(conv[1]),float(conv[2]),float(conv[3]),float(conv[4])])

Everything that is before the for cycle is executed after the cycle finishes. Can anybody help me please? I really don't understand this behavior.

Answer 1

It looks like you need to call the update method of the widgets you want to forget. This will flush the pending GUI changes. From effbot.org :

update()

Processes all pending events, calls event callbacks, completes any pending geometry management, redraws widgets as necessary, and calls all pending idle tasks. This method should be used with care, since it may lead to really nasty race conditions if called from the wrong place (from within an event callback, for example, or from a function that can in any way be called from an event callback, etc.). When in doubt, use update_idletasks instead.