Python:始终运行程序

Question

我希望这段代码永远不会破坏.所以我创建了一个无限循环和一个"goto"到开头,以防它中断.但是,它仍然无法正常工作.

root@xxx:~# cat gmail2.py 
import imaplib, re
import os
import time
import socket
socket.setdefaulttimeout(60)

def again():
        conn = imaplib.IMAP4_SSL("imap.gmail.com", 993)
        conn.login("xx@example.com", "xxx")

        while(True):
                unreadCount = re.search("UNSEEN (\d+)", conn.status("INBOX", "(UNSEEN)")[1][0]).group(1)
                print unreadCount

                if int(unreadCount) > 20:
                        os.system('heroku restart --app sss-xxxx-203')
                #os.system('ls')
                #print "Restarting server...."

                time.sleep(60)

again() 


1
Traceback (most recent call last):
  File "gmail2.py", line 22, in <module>
    again()
  File "gmail2.py", line 12, in again
    unreadCount = re.search("UNSEEN (\d+)", conn.status("INBOX", "(UNSEEN)")[1][0]).group(1)
  File "/usr/lib/python2.6/imaplib.py", line 703, in status
    typ, dat = self._simple_command(name, mailbox, names)
  File "/usr/lib/python2.6/imaplib.py", line 1060, in _simple_command
    return self._command_complete(name, self._command(name, *args))
  File "/usr/lib/python2.6/imaplib.py", line 890, in _command_complete
    raise self.abort('command: %s => %s' % (name, val))
imaplib.abort: command: STATUS => socket error: EOF

Answer 1

这里没有任何"goto"(或Python中的任何地方),也不会确保如果循环中断它会继续运行,原因有两个:

1. 如果一个异常(例如imaplib.abort抛出,程序将退出它所处的任何函数.只有try/except会阻止它结束.

2. 无论这个程序如何运行,again()都只会被调用一次.again()调用该函数后,它将完成,然后在该点之后继续.它并没有,如果代码爆发,虽然循环充当goto-,它不会返回again功能.

你真正想要的是这样的:

import imaplib, re
import os
import time
import socket
socket.setdefaulttimeout(60)

while(True):
    conn = imaplib.IMAP4_SSL("imap.gmail.com", 993)
    conn.login("xx@example.com", "xxx")

    try:
        unreadCount = re.search("UNSEEN (\d+)", conn.status("INBOX", "(UNSEEN)")[1][0]).group(1)
        print unreadCount

        if int(unreadCount) > 20:
            os.system('heroku restart --app sss-xxxx-203')
        #os.system('ls')
        #print "Restarting server...."

        time.sleep(60)
    except:
        # an error has been thrown- try again
        pass