tkFileDialog with tKinter

[Daniel M]

I am trying to make a simple app to select and operate on data. I am using Tkinter to build a GUI with four labels and four buttons, side by side. However, for some reason when I run the script, all the button commands get called, asking the user to select all files upon startup, and then afterwards the buttons do not work. Here's my code:
---

import numpy
import scipy
 
from Tkinter import *
import tkFileDialog as tkf
 
filenames = {}
 
class App:
    def __init__(self, master):
 
            frame = Frame(master)
            frame.pack()
 
            self.Name0 = Label(frame, text = "Initial Data", width=30).grid(row=0, sticky=W,columnspan=2)
            self.Name1 = Label(frame, text = "After Change #1", width=30).grid(row=1, sticky= W,columnspan=2)
            self.Name2 = Label(frame, text = "After Change #2", width=30).grid(row=2,sticky=W,columnspan=2)
            self.Name3 = Label(frame, text = "Current State", width=30).grid(row=3,sticky=W,columnspan=2)
 
            self.Butt0 = Button(frame, text = "Select", command=tkf.askopenfile()).grid(row=0,column=2)
            self.Butt1 = Button(frame, text = "Select", command=tkf.askopenfile()).grid(row=1,column=2)
            self.Butt2 = Button(frame, text = "Select", command=tkf.askopenfile()).grid(row=2,column=2)
            self.Butt3 = Button(frame, text = "Select", command=tkf.askopenfile()).grid(row=3,column=2)
 
    def openfile(self,n):
        print "Okay"
        #More will go here
 
 
root = Tk()
 
app = App(root)
 
root.mainloop()

----

The funny things is that if I remove the dependence on n from the "openfile" method, it works. But obviously, I want to import four distinct sets of data, so I need the dependence on n. This makes no sense! Please help.

[bvdet]

Your button "commands" are being executed as the code is interpreted. "command" needs to be set to a function, not what a function returns. I might initialize 4 attributes to contain the file names and assign "command" similar to this:

            self.Butt0 = Button(frame, text = "Select", command=lambda: self.ask_file_name(self.fn1)).grid(row=0,column=2)

You would need a method "ask_file_name" that would accept the variable for assignment of the file name.