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Python readline module

·173 words·1 min
Table of Contents

GNU readline 库提供了一些函数供程序调用，来允许用户修改他们键入的命令。通过这个库可以达到以下目的

  1. <TAB> 补全
  2. ↑ 或 ↓ 浏览历史命令 ...

Python 的 readline 模块对这个库进行了一层封装

通过文档可以得知其基本用法，下面举几个小例子

补全
#

import time
import readline


class Command(object):
    command_list = ['time']

    @staticmethod
    def exec_command(command):
        if command in Command.command_list:
            return getattr(Command, command)()
        return 'Command Not Found'

    @staticmethod
    def time():
        return time.ctime()

class SimpleCompleter(object):

    def __init__(self, complete_list):
        self.complete_list = complete_list

    def complete(self, text, state):
        response = None
        text = text.lower()
        if state == 0:
            if text:
                self.matches = [ s for s in self.complete_list
                                if s.startswith(text)]
            else:
                self.matches = self.complete_list

        try:
            response = self.matches[state]
        except IndexError:
            pass
        return response

readline.set_completer(SimpleCompleter(Command.command_list).complete)
readline.parse_and_bind('tab: complete')

if __name__ == '__main__':
    line = ''
    while line != 'stop':
        line = input('>>')
        result = Command.exec_command(line)
        print(result)

一个更好的示例便是 Python 的 rlcompleter 模块源代码

历史命令
#

import atexit
import readline

histfile = '/tmp/.test_history'
try:
    readline.read_history_file(histfile)
    # default history len is -1 (infinite), which may grow unruly
    readline.set_history_length(1000)
except FileNotFoundError:
    pass

atexit.register(readline.write_history_file, histfile)

if __name__ == '__main__':
    line = ''
    while line != 'exit':
        line = input('>>')

Reference
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