Question

I want to create an interactive shell type application. For example:

> ./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 
...

I could of course use a infinte loop getting user input, splitting the line to get the individual parts of the command, but is there a better way? Even in PHP (Symfony 2 Console) they allow you to create console commands to help setup web applications for example. Is there something like that in Python (I am using Python 3)

Answer 1

Just input the commands in a loop.

For parsing the input, shlex.split is a nice option. Or just go with plain 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))

The readline library adds history functionality (up arrow) and more. Python interactive shell uses it.