Question

I have an array s of Tiles with an instance variable @type:

class Tile
  Types = ["l", "w", "r"]
  def initialize(type)
    @type = type
  end
end
s = []
20.times { s << Tile.new(Tile::Types.sample)}

How do I get each Tile‘s @type? How do I return only the objects with a particular @type?

Answer 1

If you want to get an array containing each type attribute, you’ll first need to create at least a reader for @type:

class Tile
  attr_reader :type
  Types = ["l", "w", "r"]
  def initialize(type)
    @type = type

  end
end

Then use Array#map :

type_attribute_array = s.map(&:type)
#or, in longer form
type_attribute_array = s.map{|t| t.type)

If you want to filter Tile object according to their @type value, Array#select is your friend :

filtered_type_array = s.select{|t| t.type == 'some_value'}

Here’s the doc for Array : Ruby Array