使用Python和Click创建shell命令行应用程序

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

This is not impossible with click, but there's no built-in support for that either. The first you would have to do is making your group callback invokable without a subcommand by passing invoke_without_command=True into the group decorator (as described here ). Then your group callback would have to implement a REPL. Python has the cmd framework for doing this in the standard library. Making the click subcommands available there involves overriding cmd.Cmd.default , like in the code snippet below. Getting all the details right, like help , should be doable in a few lines.

import click
import cmd

class REPL(cmd.Cmd):
    def __init__(self, ctx):
        cmd.Cmd.__init__(self)
        self.ctx = ctx

    def default(self, line):
        subcommand = cli.commands.get(line)
        if subcommand:
            self.ctx.invoke(subcommand)
        else:
            return cmd.Cmd.default(self, line)

@click.group(invoke_without_command=True)
@click.pass_context
def cli(ctx):
    if ctx.invoked_subcommand is None:
        repl = REPL(ctx)
        repl.cmdloop()

@cli.command()
def a():
    """The `a` command prints an 'a'."""
    print "a"

@cli.command()
def b():
    """The `b` command prints a 'b'."""
    print "b"

if __name__ == "__main__":
    cli()

Answer 2

I was trying to do something similar to the OP, but with additional options / nested sub-sub-commands. The first answer using the builtin cmd module did not work in my case; maybe with some more fiddling.. But I did just run across click-shell . Haven't had a chance to test it extensively, but so far, it seems to work exactly as expected.

Answer 3

I know this is super old, but I've been working on fpbhb's solution to support options as well. I'm sure this could use some more work, but here is a basic example of how it could be done:

import click
import cmd
import sys

from click import BaseCommand, UsageError


class REPL(cmd.Cmd):
    def __init__(self, ctx):
        cmd.Cmd.__init__(self)
        self.ctx = ctx

    def default(self, line):
        subcommand = line.split()[0]
        args = line.split()[1:]

        subcommand = cli.commands.get(subcommand)
        if subcommand:
            try:
                subcommand.parse_args(self.ctx, args)
                self.ctx.forward(subcommand)
            except UsageError as e:
                print(e.format_message())
        else:
            return cmd.Cmd.default(self, line)


@click.group(invoke_without_command=True)
@click.pass_context
def cli(ctx):
    if ctx.invoked_subcommand is None:
        repl = REPL(ctx)
        repl.cmdloop()


@cli.command()
@click.option('--foo', required=True)
def a(foo):
    print("a")
    print(foo)
    return 'banana'


@cli.command()
@click.option('--foo', required=True)
def b(foo):
    print("b")
    print(foo)

if __name__ == "__main__":
    cli()

Answer 4

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.