Python交互式Shell类型应用程序

Question

我想创建一个交互式shell类型的应用程序.例如:

> ./app.py

Enter a command to do something. eg `create name price`. 
For to get help, enter "help" (without quotes)

> create item1 10
Created "item1", cost $10

> del item1
Deleted item1

> exit 
...

我当然可以使用infinte循环获取用户输入,拆分行以获取命令的各个部分,但是有更好的方法吗？即使在PHP(Symfony 2控制台)中,它们也允许您创建控制台命令以帮助设置Web应用程序.在Python中有类似的东西(我使用的是Python 3)

Answer 1

只是input循环中的命令.

对于解析输入,shlex.split是一个不错的选择.或者只是简单地说str.split.

import readline
import shlex

print('Enter a command to do something, e.g. `create name price`.')
print('To get help, enter `help`.')

while True:
    cmd, *args = shlex.split(input('> '))

    if cmd=='exit':
        break

    elif cmd=='help':
        print('...')

    elif cmd=='create':
        name, cost = args
        cost = int(cost)
        # ...
        print('Created "{}", cost ${}'.format(name, cost))

    # ...

    else:
        print('Unknown command: {}'.format(cmd))

该readline库添加了历史功能(向上箭头)等.Python交互式shell使用它.

Answer 2

构建此类交互式应用程序的另一种方法是使用cmd模块。

# app.py
from cmd import Cmd

class MyCmd(Cmd):

    prompt = "> "

    def do_create(self, args):
        name, cost = args.rsplit(" ", 1) # args is string of input after create
        print('Created "{}", cost ${}'.format(name, cost))

    def do_del(self, name):
        print('Deleted {}'.format(name))

    def do_exit(self, args):
        raise SystemExit()

if __name__ == "__main__":

    app = MyCmd()
    app.cmdloop('Enter a command to do something. eg `create name price`.')

这是运行上述代码的输出（如果上述代码位于名为 的文件中app.py）：

$ python app.py
Enter a command to do something. eg `create name price`.
> create item1 10
Created "item1", cost $10
> del item1
Deleted item1
> exit
$