Question

I have some difficulties for using Ruby block, passing in a method.

As in the following case, I would like to display each element of @array, from Box instance (using .each method):

class Box
  def initialize
    @array = [:foo, :bar]
  end

  def each(&block)
    # well, hm..
  end
end

a = Box.new
a.each { |element| puts element }

Answer 1

You really just need to delegate to the each method on @array and pass it the block. Additionally, you can include the Enumerable mix-in to gain access to the methods it provides (e.g. map, inject, etc…):

class Box
  include Enumerable

  def initialize
    @array = [:foo, :bar]
  end

  def each(&block)
    @array.each(&block)
  end
end

More information on the Enumerable module is available in the documentation.