Some method to generate a string of css classes

css.rb

def conditional_css(*elements)
  elements.map do |element|
    if element.kind_of?(Hash)
      element.select { |k, v| v }.keys
    else
      element.to_s
    end
  end.compact.join(' ')
end

puts conditional_css('some-klass', :another, { valid: true, invalid: false })
# => 'some-klass another valid'