Ruby mixed ideas

ruby_mix.rb

#Metaprogramming
class Meta
  def create_method(name, block)
    self.class.send(:define_method, name, block)
  end
end

m = Meta.new
method_body = -> { puts "hello no args" } 
another_method_body = lambda { |text| puts "args are: #{text}" }
m.create_method(:a, method_body) 
m.create_method(:b, another_method_body)
m.a
m.b "i arg!"

String.send(:define_method, :dupcase, -> { "DUPA " + self.to_s + " DUPA" })

# Example 8
class CarModel
  # define a class macro for setting features
  def self.features(*args)
    args.each do |feature|
      attr_accessor "#{feature}_price", "#{feature}_info"
    end
  end

  # set _info and _price methods for each of these features
  features :engine, :wheel, :airbag, :alarm, :stereo
end

#Procs

proc_one = ->(n) { n * 2 }
[1,2,3,4].map(&proc_one)

proc_two = Proc.new { |arg='default'| puts "Bloc called with: #{arg}" }

def caller(&block)
  if block_given?
    block.call
    block.call(66)
  end
end

caller(&proc_two)

class TexasHoldem::Game::Resolver
  def initialize hands, board
    @hands = hands
    @board = board
  end

  def ranking
    @hands.each(&assign_score)
    @hands.group_by(&score_value).map(&by_hand)
  end

  private


    def assign_score
      lambda { |hand| hand.best_hand = TexasHoldem::Hand::Resolver.new(hand, @board).best_hand }
    end

    def score_value
      ->(hand) { hand.best_hand.score[0] }
    end

    def by_hand
      ->(key) { key[1] }
    end
end

#hash possible keys

>> class Dupa
>> end
=> nil
>> d = Dupa.new
=> #<Dupa:0x007fddad10dbe0>
>> { d => 1 }
=> {#<Dupa:0x007fddad10dbe0>=>1}
>> { d => 1, Dupa => 2 }
=> {#<Dupa:0x007fddad10dbe0>=>1, Dupa=>2}
>> h = { d => 1, Dupa => 2 }
=> {#<Dupa:0x007fddad10dbe0>=>1, Dupa=>2}
h[dupa.class]