Why decorator-style context manager in Python doesn't catch exception within Tkinter window? -

there simple code decorator-generated context manager via contextlib. when press button exception raised , not handled context manager. why it?

from tkinter import tk, button contextlib import contextmanager   def close_window():      window.destroy()     raise exception   @contextmanager def safe():     try:         yield     except:         print 'exception catched'  safe():     window = tk()     button = button(window, text='press me', command=close_window)     button.pack()     window.mainloop() 

why exception still raise?

upd use python 2.7

the tkinter main process loop not brought down exceptions , not propagate them further. hence, exception never reaches till with statement (since tkinter catches , reports exception , stops execution).

you need create decorator catch exception , log them or whatever logic want do.

example -

from tkinter import tk, button contextlib import contextmanager  class exceptioncatcher: # <---the decorator     def __init__(self, function):         self.function = function     def __call__(self, *args, **kwargs):         try:             return self.function(*args, **kwargs)         except exception:             print 'exception catched1'   @exceptioncatcher def close_window():      window.destroy()     raise exception   @contextmanager def safe():     try:         yield     except exception:         print 'exception catched'  safe():     window = tk()     button = button(window, text='press me', command=close_window)     button.pack()     window.mainloop() 

with above code, when click on press button, logs exception catched1 me , exits.

also, not except: should give exception want catch (or atleast except exception: ).