Handling exception in python tkinter

Question

I have written an application in Python Tkinter. I recently noticed that for one of the operation, it sometimes closes (without giving any error) if that operation failed.

Answer 1

You can override Tkinter's CallWrapper. It is necessary to use a named import of Tkinter instead of a wildcard import in order to do so:

import Tkinter as tk
import traceback

class Catcher: 
    def __init__(self, func, subst, widget):
        self.func = func 
        self.subst = subst
        self.widget = widget
    def __call__(self, *args):
        try:
            if self.subst:
                args = apply(self.subst, args)
            return apply(self.func, args)
        except SystemExit, msg:
            raise SystemExit, msg
        except:
            traceback.print_exc(file=open('test.log', 'a'))

# ...
tk.CallWrapper = Catcher
b = tk.Button(master, text="OK", command=copydir)
b.pack()
master.mainloop()