ruby mixin with callbacks demo

holla.rb

module Moo
  def self.included(base)
    base.extend(ClassMethods)
  end

  def jump!
    trigger(:before_jump)
    puts 'JUMP'
    trigger(:after_jump)
  end

  def dance!
    trigger(:before_dance)
    puts 'BOOGIE DOWN'
    trigger(:after_dance)
  end

  def trigger(phase)
    self.class.class_variable_get(:@@__phases)[phase]&.call self
  end

  module ClassMethods
    [:jump, :dance].each do |action|
      [:before, :after].each do |phase|
        self.class.send(:define_method, "#{phase}_#{action}") do |&b|
          set_callback("#{phase}_#{action}".to_sym, b)
        end
      end
      # define_method("after_#{phase}") do &block
        # set_callback("after_#{phase}", &block)
      # end
    end

    protected

    def set_callback(phase, b)
      class_variable_set(:@@__phases, {}) unless class_variables.include?(:@@__phases)

      class_variable_set(
        :@@__phases,
        class_variable_get(:@@__phases).merge(
          phase => b
        )
      )
    end
  end
end

class Foo
  include Moo
  before_jump do |foo|
    puts 'mmmmilky!' unless foo.milked
  end

  after_jump { puts 'Bounce!' }

  before_dance { puts '*taps feet*' }

  attr_reader :milked

  def initialize(milked: false)
    @milked = milked
  end
end

f = Foo.new
f.jump!

puts '===='

f2 = Foo.new(milked: true)
f2.jump!
f2.dance!