106 lines
3.2 KiB
ReStructuredText
106 lines
3.2 KiB
ReStructuredText
|
|
||
|
|
:mod:`atexit` --- Exit handlers
|
||
|
|
===============================
|
||
|
|
|
||
|
|
.. module:: atexit
|
||
|
|
:synopsis: Register and execute cleanup functions.
|
||
|
|
.. moduleauthor:: Skip Montanaro <skip@mojam.com>
|
||
|
|
.. sectionauthor:: Skip Montanaro <skip@mojam.com>
|
||
|
|
|
||
|
|
|
||
|
|
.. versionadded:: 2.0
|
||
|
|
|
||
|
|
The :mod:`atexit` module defines functions to register and unregister cleanup
|
||
|
|
functions. Functions thus registered are automatically executed upon normal
|
||
|
|
interpreter termination.
|
||
|
|
|
||
|
|
Note: the functions registered via this module are not called when the program
|
||
|
|
is killed by a signal, when a Python fatal internal error is detected, or when
|
||
|
|
:func:`os._exit` is called.
|
||
|
|
|
||
|
|
|
||
|
|
.. function:: register(func[, *args[, **kargs]])
|
||
|
|
|
||
|
|
Register *func* as a function to be executed at termination. Any optional
|
||
|
|
arguments that are to be passed to *func* must be passed as arguments to
|
||
|
|
:func:`register`.
|
||
|
|
|
||
|
|
At normal program termination (for instance, if :func:`sys.exit` is called or
|
||
|
|
the main module's execution completes), all functions registered are called in
|
||
|
|
last in, first out order. The assumption is that lower level modules will
|
||
|
|
normally be imported before higher level modules and thus must be cleaned up
|
||
|
|
later.
|
||
|
|
|
||
|
|
If an exception is raised during execution of the exit handlers, a traceback is
|
||
|
|
printed (unless :exc:`SystemExit` is raised) and the exception information is
|
||
|
|
saved. After all exit handlers have had a chance to run the last exception to
|
||
|
|
be raised is re-raised.
|
||
|
|
|
||
|
|
.. versionchanged:: 2.6
|
||
|
|
This function now returns *func* which makes it possible to use it as a
|
||
|
|
decorator without binding the original name to ``None``.
|
||
|
|
|
||
|
|
|
||
|
|
.. function:: unregister(func)
|
||
|
|
|
||
|
|
Remove a function *func* from the list of functions to be run at interpreter-
|
||
|
|
shutdown. After calling :func:`unregister`, *func* is guaranteed not to be
|
||
|
|
called when the interpreter shuts down.
|
||
|
|
|
||
|
|
.. versionadded:: 3.0
|
||
|
|
|
||
|
|
|
||
|
|
.. seealso::
|
||
|
|
|
||
|
|
Module :mod:`readline`
|
||
|
|
Useful example of :mod:`atexit` to read and write :mod:`readline` history files.
|
||
|
|
|
||
|
|
|
||
|
|
.. _atexit-example:
|
||
|
|
|
||
|
|
:mod:`atexit` Example
|
||
|
|
---------------------
|
||
|
|
|
||
|
|
The following simple example demonstrates how a module can initialize a counter
|
||
|
|
from a file when it is imported and save the counter's updated value
|
||
|
|
automatically when the program terminates without relying on the application
|
||
|
|
making an explicit call into this module at termination. ::
|
||
|
|
|
||
|
|
try:
|
||
|
|
_count = int(open("/tmp/counter").read())
|
||
|
|
except IOError:
|
||
|
|
_count = 0
|
||
|
|
|
||
|
|
def incrcounter(n):
|
||
|
|
global _count
|
||
|
|
_count = _count + n
|
||
|
|
|
||
|
|
def savecounter():
|
||
|
|
open("/tmp/counter", "w").write("%d" % _count)
|
||
|
|
|
||
|
|
import atexit
|
||
|
|
atexit.register(savecounter)
|
||
|
|
|
||
|
|
Positional and keyword arguments may also be passed to :func:`register` to be
|
||
|
|
passed along to the registered function when it is called::
|
||
|
|
|
||
|
|
def goodbye(name, adjective):
|
||
|
|
print 'Goodbye, %s, it was %s to meet you.' % (name, adjective)
|
||
|
|
|
||
|
|
import atexit
|
||
|
|
atexit.register(goodbye, 'Donny', 'nice')
|
||
|
|
|
||
|
|
# or:
|
||
|
|
atexit.register(goodbye, adjective='nice', name='Donny')
|
||
|
|
|
||
|
|
Usage as a decorator::
|
||
|
|
|
||
|
|
import atexit
|
||
|
|
|
||
|
|
@atexit.register
|
||
|
|
def goodbye():
|
||
|
|
print "You are now leaving the Python sector."
|
||
|
|
|
||
|
|
This obviously only works with functions that don't take arguments.
|
||
|
|
|