CLI builder example

cli_builder.rb

module HashConstructor
  def initialize(attrs = {})
    attrs.each do |name, value|
      send("#{name}=", value)
    end
  end
end

class AwsCli
  include HashConstructor
  attr_accessor :region

  def s3(bucket)
    S3.new(aws: self, bucket: bucket)
  end

  def help
    run('help')
  end

  def run(*args)
    system('aws', '--region', region, *args)
  end

  class S3
    include HashConstructor

    attr_accessor :aws, :bucket

    def ls
      run('ls', bucket)
    end

    def run(*args)
      aws.run('s3', *args)
    end
  end
end

aws = AwsCli.new(region: 'us-west-2')
aws.help
aws.s3('zoomer-menus-images-testing').ls