First DSL

show.haml

-# to DRY usage of bootstrap hovered table with small font that used to SHOW model attributes was created a simple DSL 

-# can assign new table with 2 columns (attribute name, attribute value)
-# can add header row/rows and content rows

= ShowTable::TableGenerator.generate_table(self) do
  - add_header('Название атрибута', { width: '30%' })
  - add_header('Значение атрибута')

  - add_row('Имя') do
    - @contact.first_name

  - add_row('Фамилия') do
    - @contact.second_name

table_generator.rb

class ShowTable::TableGenerator

  attr_reader :headers, :rows

  class << self

    def table(context, &block)
      @headers = []
      @rows = []
      # view render context
      @c = context

      # check if render context is defined, it's important
      if @c
        # we can skip this and render only empty table, this is allowed
        instance_eval(&block) if block_given?
      else
        raise 'View Context must be defined'
      end

      # generate whole table with head rows and body rows
      generate_table_structure
    end

    # add instance of header_row generators and body_row generators to array
    def header(title, params = {}, &block)
       @headers << HeaderCell.new(title, params, &block)
    end

    def row(title, params = {}, &block)
      @rows << RowRenderer.new(title, params, &block)
    end

  end

  private

  class << self

    # Generate whole table
    # with bootstrap 3.+ small font size, and table hovered effects
    def generate_table_structure

      head = @c.content_tag :thead, HeaderRowRenderer.new(@headers).generate_html(@c)
      body = @c.content_tag :tbody do
        @c.raw( @rows.map{|header| header.generate_html(@c) }.join)
      end

      @c.content_tag :div, nil, class: 'small' do
        @c.content_tag :table, nil, class: 'table table-hover' do
          head + body
        end
      end
    end

  end

end

class RowRenderer

  ROW_TAG = :tr

  attr_reader :context, :title, :params, :block

  def initialize(title, params = {}, &block)
    @title = title
    @params = params
    @block = block
  end

  # Generate table row using view context and params
  def generate_html(context)
    td_title = context.content_tag(:td, context.content_tag(:b, @title))
    if @block
      td_content = context.content_tag(:td, context.instance_eval(&@block))
    else
      td_content = context.content_tag(:td, '')
    end
    context.content_tag(ROW_TAG , td_title + td_content, @params)
  end

end

class HeaderRowRenderer

  attr_reader :header_cells

  def initialize(header_cells)
    @header_cells = header_cells
  end

  def generate_html(context)
    content = ''
    @header_cells.each do |cell|
      content << context.content_tag(:th, cell.title, cell.params)
    end

    return context.content_tag(:tr, context.raw(content))
  end

end

class HeaderCell

  attr_reader :title, :params

  def initialize(title, params, &block)
    @title = title
    @params = params
    @block = block
  end

end