1"""
2atexit.py - allow programmer to define multiple exit functions to be executed
3upon normal program termination.
4
5One public function, register, is defined.
6"""
7
8__all__ = ["register"]
9
10import sys
11
12_exithandlers = []
13def _run_exitfuncs():
14    """run any registered exit functions
15
16    _exithandlers is traversed in reverse order so functions are executed
17    last in, first out.
18    """
19
20    exc_info = None
21    while _exithandlers:
22        func, targs, kargs = _exithandlers.pop()
23        try:
24            func(*targs, **kargs)
25        except SystemExit:
26            exc_info = sys.exc_info()
27        except:
28            import traceback
29            print >> sys.stderr, "Error in atexit._run_exitfuncs:"
30            traceback.print_exc()
31            exc_info = sys.exc_info()
32
33    if exc_info is not None:
34        raise exc_info[0], exc_info[1], exc_info[2]
35
36
37def register(func, *targs, **kargs):
38    """register a function to be executed upon normal program termination
39
40    func - function to be called at exit
41    targs - optional arguments to pass to func
42    kargs - optional keyword arguments to pass to func
43
44    func is returned to facilitate usage as a decorator.
45    """
46    _exithandlers.append((func, targs, kargs))
47    return func
48
49if hasattr(sys, "exitfunc"):
50    # Assume it's another registered exit function - append it to our list
51    register(sys.exitfunc)
52sys.exitfunc = _run_exitfuncs
53
54if __name__ == "__main__":
55    def x1():
56        print "running x1"
57    def x2(n):
58        print "running x2(%r)" % (n,)
59    def x3(n, kwd=None):
60        print "running x3(%r, kwd=%r)" % (n, kwd)
61
62    register(x1)
63    register(x2, 12)
64    register(x3, 5, "bar")
65    register(x3, "no kwd args")
66