atexit
— 退出处理程序
¶
atexit
module defines functions to register and unregister cleanup functions. Functions thus registered are automatically executed upon normal interpreter termination.
atexit
runs these functions in the
reverse
order in which they were registered; if you register
A
,
B
，和
C
, at interpreter termination time they will be run in the order
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。
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。
atexit.
unregister
(
func
)
¶
移除
func
from the list of functions to be run at interpreter shutdown. After calling
unregister()
,
func
is guaranteed not to be called when the interpreter shuts down, even if it was registered more than once.
unregister()
silently does nothing if
func
先前未注册。
atexit
范例
¶
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:
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)
Positional and keyword arguments may also be passed to
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')
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。