"""

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

    """

    _exithandlers.append((func, targs, kargs))

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")