Cliffy should allow to pass option with empty value if option is declared as optional.

[scandinave]

Hi,
In my use case i have an option defined like this:

  .option('-v, --version <number:semver>',  'The version part of the tag <repo>/<image>:<platform>-<version>-<qualifer>')

This option is called inside a CI pipeline like this:

myCli command --version '${params.RELEASE_VERSION}'

params.RELEASE_VERSION can be a string or empty depending of the user that trigger the pipeline. Currently, Cliffy throw an exception error: Missing value for option "--version". This forces me to due parsing to only add --version if RELEASE_VERSION is not empty.

I expect that an optional option can also be specifying with empty value.

[fritogotlayed]

I have a similar issue where at least allowing a empty string to be provided to an option would be useful. In my case a empty string in the option is significantly different than the omission of the option. It can be though of similar to a nullable boolean. Right now I have to include a second option and make them conflict with one another as a work around. Granted my use case is around collapsing multiple .env and .env.xyz files into a .envrc with a slightly different format.

Example (can also be seen here):

import { Command, ArgumentValue } from '@cliffy/command';

function nullableBooleanType({ label, name, value }: ArgumentValue): boolean | undefined {
  if (value === 'true' || value === '1') {
    return true;
  }
  if (value === 'false' || value === '0') {
    return false;
  }
  return undefined;
}

export const writeEnv = new Command()
  .name('sample')
  .description('example')
  .type('nullableBoolean', nullableBooleanType)
  .option(
    '-d, --dir <dir:string>',
    '...',
  )
  .option(
    '-e, --env <env:string>',
    '...',
  )
  // NOTE: If we can figure out how to use -e "" and be valid that would remove the need for the baseEnv option
  //       and we can just use -e "" to indicate that we want to use the base .env file
  //       Look into the `value` callback on the above option.
  .option(
    '--base-env',
    '...',
    {default: false, conflicts: ['env']},
  )
  .option(
    '--include-local <includeLocal:nullableBoolean>',
    '...',
    {default: undefined},
  )
  .action(async ({ dir, env, baseEnv, includeLocal }) => { /* implementation */ });

Having the ability to provide a empty string and undefined to the env argument would help reduce complexity. I would love to know if there is a way to support this or if I'm stuck with the work around I have in place.