1 \section{\module{atexit
} ---
4 \declaremodule{standard
}{atexit
}
5 \moduleauthor{Skip Montanaro
}{skip@mojam.com
}
6 \sectionauthor{Skip Montanaro
}{skip@mojam.com
}
7 \modulesynopsis{Register and execute cleanup functions.
}
11 The
\module{atexit
} module defines a single function to register
12 cleanup functions. Functions thus registered are automatically
13 executed upon normal interpreter termination.
15 Note: the functions registered via this module are not called when the program is killed by a
16 signal, when a Python fatal internal error is detected, or when
17 \function{os._exit()
} is called.
19 This is an alternate interface to the functionality provided by the
20 \code{sys.exitfunc
} variable.
21 \withsubitem{(in sys)
}{\ttindex{exitfunc
}}
23 Note: This module is unlikely to work correctly when used with other code
24 that sets
\code{sys.exitfunc
}. In particular, other core Python modules are
25 free to use
\module{atexit
} without the programmer's knowledge. Authors who
26 use
\code{sys.exitfunc
} should convert their code to use
27 \module{atexit
} instead. The simplest way to convert code that sets
28 \code{sys.exitfunc
} is to import
\module{atexit
} and register the function
29 that had been bound to
\code{sys.exitfunc
}.
31 \begin{funcdesc
}{register
}{func
\optional{, *args
\optional{, **kargs
}}}
32 Register
\var{func
} as a function to be executed at termination. Any
33 optional arguments that are to be passed to
\var{func
} must be passed
34 as arguments to
\function{register()
}.
36 At normal program termination (for instance, if
37 \function{sys.exit()
} is called or the main module's execution
38 completes), all functions registered are called in last in, first out
39 order. The assumption is that lower level modules will normally be
40 imported before higher level modules and thus must be cleaned up
43 If an exception is raised during execution of the exit handlers, a
44 traceback is printed (unless
\exception{SystemExit
} is raised) and the
45 exception information is saved. After all exit handlers have had a
46 chance to run the last exception to be raised is re-raised.
48 \versionchanged[This function now returns
\var{func
} which makes it
49 possible to use it as a decorator without binding the
50 original name to
\code{None
}]{2.6}
55 \seemodule{readline
}{Useful example of
\module{atexit
} to read and
56 write
\refmodule{readline
} history files.
}
60 \subsection{\module{atexit
} Example
\label{atexit-example
}}
62 The following simple example demonstrates how a module can initialize
63 a counter from a file when it is imported and save the counter's
64 updated value automatically when the program terminates without
65 relying on the application making an explicit call into this module at
70 _count = int(open("/tmp/counter").read())
79 open("/tmp/counter", "w").write("
%d" % _count)
82 atexit.register(savecounter)
85 Positional and keyword arguments may also be passed to
86 \function{register()
} to be passed along to the registered function
90 def goodbye(name, adjective):
91 print 'Goodbye,
%s, it was %s to meet you.' % (name, adjective)
94 atexit.register(goodbye, 'Donny', 'nice')
97 atexit.register(goodbye, adjective='nice', name='Donny')
100 Usage as a decorator:
107 print "You are now leaving the Python sector."
110 This obviously only works with functions that don't take arguments.