componenta_example.rb

Comment = Struct.new(:title, :body, :author)

class Comment::Item
  include Componenta

  render :html do 
    h1 object.title
    div object.body
    span object.author
  end

  render :json do 
    title object.title
    body object.body
    author object.author
  end
end

comment = Comment.new("Test", "This is first comment", "Ivan")
Comment::Item.new(comment).render # => "<h1>Test</h1><div>This is first comment</div><span>Ivan</span>"
Comment::Item.new(comment).render(:json) # => '{"title":"Test","body":"This is first comment","author":"Ivan"}'