`atexit` — 退出处理程序 ¶

The atexit 模块定义用于注册和取消注册清理函数的函数。因此，会自动执行注册函数当解释器正常终止时。 atexit 运行这些函数按 reverse 次序当注册它们时；若注册 A , B ，和 C ，解释器终止时，运行它们将按次序 C , B , A .

注意： The functions registered via this module are not called when the program is killed by a signal not handled by Python, when a Python fatal internal error is detected, or when os._exit() 被调用。

注意： The effect of registering or unregistering functions from within a cleanup function is undefined.

3.7 版改变： When used with C-API subinterpreters, registered functions are local to the interpreter they were registered in.

atexit. register ( func , * args , ** kwargs ) ¶

注册 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 register() . It is possible to register the same function and arguments more than once.

At normal program termination (for instance, if 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 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.

此函数返回 func ，从而可将其用作装饰器。

警告

Starting new threads or calling os.fork() from a registered function can lead to race condition between the main Python runtime thread freeing thread states while internal threading routines or the new process try to use that state. This can lead to crashes rather than clean shutdown.

3.12 版改变： Attempts to start a new thread or os.fork() a new process in a registered function now leads to RuntimeError .

atexit. unregister ( func ) ¶: 移除 func from the list of functions to be run at interpreter shutdown. unregister() silently does nothing if func was not previously registered. If func has been registered more than once, every occurrence of that function in the atexit call stack will be removed. Equality comparisons ( == ) are used internally during unregistration, so function references do not need to have matching identities.

另请参阅

模块 readline: Useful example of atexit 以读写 readline 历史文件。

`atexit` 范例 ¶

以下简单范例演示导入模块时如何从文件初始化计数器，并在程序终止时自动保存计数器更新值 (终止时不依赖应用程序对此模块做出的明确调用)。

try:
    with open('counterfile') as infile:
        _count = int(infile.read())
except FileNotFoundError:
    _count = 0
def incrcounter(n):
    global _count
    _count = _count + n
def savecounter():
    with open('counterfile', 'w') as outfile:
        outfile.write('%d' % _count)
import atexit
atexit.register(savecounter)

也可以把位置和关键词自变量传递给 register() 以沿注册函数传递当调用时：

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')

用作装饰器 :

import atexit
@atexit.register
def goodbye():
    print('You are now leaving the Python sector.')

这仅适用于可不带自变量调用的函数。

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atexit — 退出处理程序 ¶

atexit 范例 ¶

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`atexit` — 退出处理程序 ¶

`atexit` 范例 ¶