删除和更新Python文本文件中的行

Question

我正在学习Python，作为一个学习项目，我正在开发一个twitter机器人。我用的是python3。我在tweet中使用以下行。你知道吗

What is Bruce Lee’s favorite drink? Wataaaaah!
The dyslexic devil worshipper sold his soul to Santa.
You kill vegetarian vampires with a steak to the heart.
There was a prison break and I saw a midget climb up the fence. As he jumped down he sneered at me and I thought, well that’s a little condescending.

这是我使用Twython发tweet的代码：

from twython import Twython, TwythonError
import time

APP_KEY = '##########'  # Customer Key here
APP_SECRET = '#############'  # Customer secret here
OAUTH_TOKEN = '###############'  # Access Token here
OAUTH_TOKEN_SECRET = '################'  # Access Token Secret here

twitter = Twython(APP_KEY, APP_SECRET, OAUTH_TOKEN, OAUTH_TOKEN_SECRET)

try:
    with open('jokes.txt', 'r+') as file:
        buff = file.readlines()

    for line in buff:
        if len(line)<140:
            print ("Tweeting...")
            twitter.update_status(status=line)
            time.sleep(3)
            with open ('jokes.txt', 'r+') as file:
                buff.remove(line)
                file.writelines(buff)
        else:
            with open ('jokes.txt', 'r+') as file:
                buff.remove(line)
                file.writelines(buff)
            print ("Skipped line - Char Length Violation")
            continue


except TwythonError as e:
    print (e)

我想跳过控制台上消息中超过140个字符的行Skipped line - Char Length Violation，然后删除该行并更新文件。脚本通过忽略该行成功发送tweet，但无法打印控制台消息。它也无法从文本文件中删除该行。你知道吗

我不知道为什么第三行You kill vegetarian vampires with a steak to the heart.被跳过了。你知道吗

我的代码有什么问题，为什么在运行脚本后文本文件看起来像这样：

The dyslexic devil worshipper sold his soul to Santa.
There was a prison break and I saw a midget climb up the fence. As he jumped down he sneered at me and I thought, well that’s a little condescending.d at me and I thought, well that’s a little condescending.nd I thought, well that’s a little condescending.

Answer 1

首先，尽量避免使用file来命名变量，因为它是Python中用于类型file的保留关键字。你知道吗

固定代码：

from twython import Twython, TwythonError
import time

APP_KEY = '##########'  # Customer Key here
APP_SECRET = '#############'  # Customer secret here
OAUTH_TOKEN = '###############'  # Access Token here
OAUTH_TOKEN_SECRET = '################'  # Access Token Secret here

twitter = Twython(APP_KEY, APP_SECRET, OAUTH_TOKEN, OAUTH_TOKEN_SECRET)

try:
    with open('jokes.txt', 'r+') as fp:
        buff = fp.readlines()

    for line in buff[:]:
        if len(line) < 140:
            print("Tweeting...")
            twitter.update_status(status=line)
            time.sleep(3)
            with open('jokes.txt', 'w') as fp:
                buff.remove(line)
                fp.writelines(buff)
        else:
            with open('jokes.txt', 'w') as fp:
                buff.remove(line)
                fp.writelines(buff)
            print("Skipped line - Char Length Violation")
            continue


except TwythonError as e:
    print(e)

通常-就像在本例中-在循环内修改iterable（列表）不是一个好主意，循环对同一iterable进行迭代。这里的技巧是第for line in buff[:]:行中的切片操作符，它生成buff列表的副本，并在副本上而不是在原始的buff列表上迭代。你知道吗

另外，如果要覆盖文件，必须以“w”模式打开，而不是以“r+”模式打开，因为“r+”不会首先截断文件。你知道吗