How Ruby methods are resolved

method_dispatch.rb

module B
  def speak
    'B'
  end
end

module C
  def speak
    'C'
  end
end

class A
  include B
end

puts A.new.speak

A.send :include, C

puts A.new.speak

class A
  def speak
    'A'
  end
end

puts A.new.speak

a = A.new

puts a.speak

def a.speak
  'a'
end

puts a.speak