'''

'''
    @functools.wraps(func)
    def f(*args,**kwargs):
        import socket
        try:
# 全局屬性，否則變量會在方法退出后被銷毀
            global s
            s = socket.socket()
            host = socket.gethostname()
            s.bind((host, 60123))
        except:
            print('already has an instance')
            return None
        return func(*args,**kwargs)
    return f
[code]
在腳本的主函數上使用：
[code]
@just_one_instance
main():
    do sth.