从raw_input()读取输入,而不会被Python中的其他线程覆盖

Question

我试图让用户使用raw_input()在控制台上输入命令,这很好用.问题是我有后台线程偶尔会将日志信息输出到屏幕上,当它们发生时它们会搞砸输入提示(因为输出会转到光标恰好在哪里).

这是一个小Python程序,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

这是我运行它时的样子:

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.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> 

关于如何在不诉诸丑陋黑客的情况下实现这一目标的任何想法？:)

Answer 1

我最近遇到了这个问题,并希望将此解决方案留在此处以供将来参考.这些解决方案从终端清除待处理的raw_input(readline)文本,打印新文本,然后重新打印到raw_input缓冲区中的终端.

第一个程序非常简单,但只有当只有一行文本等待raw_input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个或更多缓冲行,但具有更多(标准)模块依赖性并且需要一点点终端hackery:

#!/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.之前的readline行已正确清除:

$ ./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:

如何在Python中获取Linux控制台窗口宽度

像列输出一样 - python库 (此代码示例显示如何获取Unix或Windows的终端宽度)

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