require "benchmark/ips"

class A
  def x; raise "original method not overridden"; end
  def y; raise "original method not overridden"; end
end

module AMod
  attr_accessor :x_val, :y_val
  def x; puts x_val end
  def y; puts y_val end
end

module BMod
  attr_accessor :x_val, :y_val
  def x
    return super unless x_val
    puts x_val
  end
  def y
    return super unless y_val
    puts y_val
  end
end

class B < A
  prepend BMod
end

def include_module_at_runtime x_val, y_val
  a = A.new
  a.singleton_class.include AMod
  a.x_val = x_val
  a.y_val = y_val
  a.x
  a.y
end

def set_instance_variables x_val, y_val
  a = B.new
  a.x_val = x_val
  a.y_val = y_val
  a.x
  a.y
end

def define_module_at_runtime x_val, y_val
  mod = Module.new do
    define_method(:x) { puts x_val }
    define_method(:y) { puts y_val }
  end
  a = A.new
  a.singleton_class.include mod
  a.x
  a.y
end

def define_methods_at_runtime x_val, y_val
  a = A.new
  a.define_singleton_method(:x) { puts x_val }
  a.define_singleton_method(:y) { puts y_val }
  a.x
  a.y
end

Benchmark.ips do |x|
  %w[include_module_at_runtime set_instance_variables define_module_at_runtime
     define_methods_at_runtime].each do |method|
    x.report(method) do
      send method, 1, 2
    end
  end
  x.compare!
end

# Comparison:
# set_instance_variables:    78453.9 i/s
# define_methods_at_runtime:    58676.1 i/s - 1.34x  slower
# include_module_at_runtime:    57551.2 i/s - 1.36x  slower
# define_module_at_runtime:    49288.7 i/s - 1.59x  slower