An example of conditionally prompting for options when a flag is set using the click library.

click_conditional_options.py

import click


def prompt_proxy(ctx, param, use_proxy):
    if use_proxy:
        host = ctx.params.get('proxy_host')
        if not host:
            host = click.prompt('Proxy host', default='localhost')

        port = ctx.params.get('proxy_port')
        if not port:
            port = click.prompt('Proxy port', default=9000)

        return (host, port)


@click.command()
@click.option('--use-proxy/--no-proxy', is_flag=True, default=False, callback=prompt_proxy)
@click.option('--proxy-host', is_eager=True)
@click.option('--proxy-port', is_eager=True, type=int)
def cli(use_proxy, proxy_host, proxy_port):
    if use_proxy:
        click.echo('Using proxy {}:{}'.format(*use_proxy))
    else:
        click.echo('Not using proxy.')


if __name__ == '__main__':
    cli()

This is an example of conditionally prompting for options if an option flag is True. When handling options in this way we need to manually handle options entered on the command line.

Notes:

• The flag cannot be set for is_eager. is_eager=False
• The conditional options must be set for is_eager. is_eager=True
• The conditional options must have their value exposed. expose_value=True

Examples:

1. Default to False and don't prompt.

   > python click_conditional_options.py
   Not using proxy.
   

2. Enable proxy and prompt.

   > python click_conditional_options.py --use-proxy
   Proxy host [localhost]:
   Proxy port [9000]:
   Using proxy localhost:9000
   

3. Enable proxy and prompt for host only.

   > python click_conditional_options.py --use-proxy --proxy-port=9001
   Proxy host [localhost]:
   Using proxy localhost:9001