Magic First and Last Indicator in a Loop in Ruby/Rails?

Question

Ruby/Rails does lots of cool stuff when it comes to sugar for basic things, and I think there\'s a very common scenario that I was wondering if anyone has done a helper or s

Answer 1

As many have pointed out, each_with_index seems to be the key to this. I have this code block that I liked.

array.each_with_index do |item,index|
  if index == 0
    # first item
  elsif index == array.length-1
    # last item
  else
    # middle items
  end
  # all items
end

Or

array.each_with_index do |item,index|
  if index == 0
    # first item
  end
  # all items
  if index == array.length-1
    # last item
  end
end

Or by Array extensions

class Array

  def each_with_position
    array.each_with_index do |item,index|
      if index == 0
        yield item, :first
      elsif index == array.length-1
        yield item, :last
      else
        yield item, :middle
      end
    end
  end

  def each_with_index_and_position
    array.each_with_index do |item,index|
      if index == 0
        yield item, index, :first
      elsif index == array.length-1
        yield item, index, :last
      else
        yield item, index, :middle
      end
    end
  end

  def each_with_position_and_index
    array.each_with_index do |item,index|
      if index == 0
        yield item, :first, index
      elsif index == array.length-1
        yield item, :last, index
      else
        yield item, :middle, index
      end
    end
  end

end