Introduction

In Qiita's comment, when I checked the click that was introduced, I found that it was easy to implement subcommands, so I will summarize how to do it. A subcommand is a command in which the first argument of the script is a command, which is a format found in version control commands such as git and svn, and django's project management script manage.py.

Environment

click is not a standard python package, so install it with pip.

$ pip install click

Basic

The basic code looks like this:

import click

@click.group(invoke_without_command=True)
@click.pass_context
def cli(ctx):
    if ctx.invoked_subcommand is None:
        print ctx.get_help()
    else:
        print('gonna invoke %s' % ctx.invoked_subcommand)


@cli.command(help='description 1')
@click.argument('target', required=False)
def subcommand1(target):
    print "sub command 1"

@cli.command(help='description 2')
@click.argument('target', required=False)
def subcommand2(target):
    print "sub command 2"

if __name__ == '__main__': cli()

cli is the starting function for everything, and subcommand1 and subcommand2 are the implementations of the subcommands, respectively. Enter each description as a help variable in @ cli.command. The following shows the contents of the command help displayed.

Usage: sample.py [OPTIONS] COMMAND [ARGS]...

Options:
  --help  Show this message and exit.

Commands:
  subcommand1  description 1
  subcommand2  description 2

You can see that subcommands 1 and 2 are registered in Commands.

Tips

Create shortcut

(Sub) The command name may be too long and you may want to create a shortcut command. In that case, extend the Group class and implement it.

...

class AliasedGroup(click.Group):
    def get_command(self, ctx, cmd_name):
        rv = click.Group.get_command(self, ctx, cmd_name)
        if rv is not None:
            return rv

        if cmd_name == 'shortcut':
            return click.Group.get_command(self, ctx, 'subcommand1')

        return None

@click.group(cls=AliasedGroup, invoke_without_command=True)
@click.pass_context
def cli(ctx):
...

As above, specify the AliasedGroup implemented as the cls argument of @ click.group. Then

$ python ./sample.py shortcut
gonna invoke shortcut
sub command 1

The implementation of sabcommand1 works as above.

Make a normal commands implementation a subcommand

If you want to divide into multiple files and implement subcommands, you can implement the command and add it to the group.

@click.group(invoke_without_command=True)
@click.pass_context
def handle(ctx):
    if ctx.invoked_subcommand is None:
        print ctx.get_help()
    else:
        print('gonna invoke %s' % ctx.invoked_subcommand)

@click.command()
def hoge():
    pass

handle.add_command(hoge)

from now on

As soon as I try it, I would like to introduce the implementation of concatenated commands.