Creating a shell command line application with Python and Click

Question

I'm using click (http://click.pocoo.org/3/) to create a command line application, but I don't know how to create a shell for this application.
Suppose I'm writing a program called test and I have commands called subtest1 and subtest2

I was able to make it work from terminal like:

$ test subtest1
$ test subtest2

But what I was thinking about is a shell, so I could do:

$ test  
>> subtest1  
>> subtest2

Is this possible with click?

Answer 1

There is now a library called click_repl that does most of the work for you. Thought I'd share my efforts in getting this to work.

The one difficulty is that you have to make a specific command the repl command, but we can repurpose @fpbhb's approach to allow calling that command by default if another one isn't provided.

This is a fully working example that supports all click options, with command history, as well as being able to call commands directly without entering the REPL:

import click
import click_repl
import os
from prompt_toolkit.history import FileHistory

@click.group(invoke_without_command=True)
@click.pass_context
def cli(ctx):
    """Pleasantries CLI"""
    if ctx.invoked_subcommand is None:
        ctx.invoke(repl)

@cli.command()
@click.option('--name', default='world')
def hello(name):
    """Say hello"""
    click.echo('Hello, {}!'.format(name))

@cli.command()
@click.option('--name', default='moon')
def goodnight(name):
    """Say goodnight"""
    click.echo('Goodnight, {}.'.format(name))

@cli.command()
def repl():
    """Start an interactive session"""
    prompt_kwargs = {
        'history': FileHistory(os.path.expanduser('~/.repl_history'))
    }
    click_repl.repl(click.get_current_context(), prompt_kwargs=prompt_kwargs)

if __name__ == '__main__':
    cli(obj={})

Here's what it looks like to use the REPL:

$ python pleasantries.py
> hello
Hello, world!
> goodnight --name fpbhb
Goodnight, fpbhb.

And to use the command line subcommands directly:

$ python pleasntries.py goodnight
Goodnight, moon.