"""
atexit.py - allow programmer to define multiple exit functions to be executed
upon normal program termination.

One public function, register, is defined.
"""

__all__ = ["register"]

import sys

_exithandlers = []
def _run_exitfuncs():
"""run any registered exit functions

_exithandlers is traversed in reverse order so functions are executed
last in, first out.
"""

exc_info = None
while _exithandlers:
func, targs, kargs = _exithandlers.pop()
try:
func(*targs, **kargs)
except SystemExit:
exc_info = sys.exc_info()
except:
import traceback
print >> sys.stderr, "Error in atexit._run_exitfuncs:"
traceback.print_exc()
exc_info = sys.exc_info()

if exc_info is not None:
raise exc_info[0], exc_info[1], exc_info[2]


def register(func, *targs, **kargs):
"""register a function to be executed upon normal program termination

func - function to be called at exit
targs - optional arguments to pass to func
kargs - optional keyword arguments to pass to func

func is returned to facilitate usage as a decorator.
"""
_exithandlers.append((func, targs, kargs))
return func

if hasattr(sys, "exitfunc"):
# Assume it's another registered exit function - append it to our list
register(sys.exitfunc)
sys.exitfunc = _run_exitfuncs

if __name__ == "__main__":
def x1():
print "running x1"
def x2(n):
print "running x2(%r)" % (n,)
def x3(n, kwd=None):
print "running x3(%r, kwd=%r)" % (n, kwd)

register(x1)
register(x2, 12)
register(x3, 5, "bar")
register(x3, "no kwd args")