使用Python中的raw_input()从输入中读取数据，而不被其他线程所覆盖。

Question

我正试图让用户使用raw_input（）在控制台输入命令，这很好。问题是我有一些后台线程，它们偶尔会将日志信息输出到屏幕上，当它们这样做时，它们会弄乱输入提示（因为此时光标正好在哪里，输出就在哪里）。

这是一个小的Python程序，它说明了我的意思。

#!/usr/bin/env python
import threading
import time

def message_loop():
    while True:
        time.sleep(1)
        print "Hello World"

thread = threading.Thread(target = message_loop)
thread.start()

while True:
    input = raw_input("Prompt> ")
    print "You typed", input

这是我运行它时它的外观示例：

Prompt> Hello World
Hello World
Hello World
Hello World
test
You typed test
Prompt> Hello World
Hello World
Hello World
hellHello World
o
You typed hello
Prompt> Hello World
Hello World
Hello World
Hello World

我想要的是提示与线程的输出一起移动。就像这样：

Hello World
Hello World
Prompt> test
You typed test
Hello World
Hello World
Hello World
Hello World
Hello World
Prompt> hello
You typed hello
Hello World
Hello World
Hello World
Hello World
Prompt> 

有没有办法在不使用丑陋的黑客手段的情况下实现这一目标？：）

Answer 1

我最近遇到了这个问题，希望把这个解决方案留在这里供以后参考。 这些解决方案从终端清除挂起的原始输入（readline）文本，打印新文本，然后将原始输入缓冲区中的内容重新打印到终端。

第一个程序非常简单，但只有在只有一行文本等待原始输入时才能正常工作：

#!/usr/bin/python

import time,readline,thread,sys

def noisy_thread():
    while True:
        time.sleep(3)
        sys.stdout.write('\r'+' '*(len(readline.get_line_buffer())+2)+'\r')
        print 'Interrupting text!'
        sys.stdout.write('> ' + readline.get_line_buffer())
        sys.stdout.flush()

thread.start_new_thread(noisy_thread, ())
while True:
    s = raw_input('> ')

输出：

$ ./threads_input.py
Interrupting text!
Interrupting text!
Interrupting text!
> WELL, PRINCE, Genoa and Lucca are now no more than private estates of the Bo
Interrupting text!
> WELL, PRINCE, Genoa and Lucca are now no more than private estates of the Bo
naparte family. No, I warn you, that if you do not tell me we are at war,

第二个正确处理2个或更多缓冲线，但有更多（标准）模块依赖性，需要少量终端黑客：

#!/usr/bin/python

import time,readline,thread
import sys,struct,fcntl,termios

def blank_current_readline():
    # Next line said to be reasonably portable for various Unixes
    (rows,cols) = struct.unpack('hh', fcntl.ioctl(sys.stdout, termios.TIOCGWINSZ,'1234'))

    text_len = len(readline.get_line_buffer())+2

    # ANSI escape sequences (All VT100 except ESC[0G)
    sys.stdout.write('\x1b[2K')                         # Clear current line
    sys.stdout.write('\x1b[1A\x1b[2K'*(text_len/cols))  # Move cursor up and clear line
    sys.stdout.write('\x1b[0G')                         # Move to start of line


def noisy_thread():
    while True:
        time.sleep(3)
        blank_current_readline()
        print 'Interrupting text!'
        sys.stdout.write('> ' + readline.get_line_buffer())
        sys.stdout.flush()          # Needed or text doesn't show until a key is pressed


if __name__ == '__main__':
    thread.start_new_thread(noisy_thread, ())
    while True:
        s = raw_input('> ')

输出。正确清除以前的阅读行：

$ ./threads_input2.py
Interrupting text!
Interrupting text!
Interrupting text!
Interrupting text!
> WELL, PRINCE, Genoa and Lucca are now no more than private estates of the Bo
naparte family. No, I warn you, that if you do not tell me we are at war,

---

有用的来源：

How to get Linux console window width in Python

apt like column output - python library （此代码示例演示如何获取Unix或Windows的终端宽度）

http://en.wikipedia.org/wiki/ANSI_escape_code