Ruby instance method before-and-after hooks demo

before_after_hooks_demo.rb

# quick and dirty demo
class Foo
  include(Module.new do
    def self.included(including_class)
      including_class.extend(StaticMethods)
      including_class.prepend(Hooks)
    end

    module Hooks; end

    module StaticMethods
      def hook(fn, before: nil, after: nil)
        Hooks.define_method(fn) do |*args, **kwargs, &block|
          before.call if before
          super(*args, **kwargs, &block)
          after.call if after
        end
      end
    end
  end)
  
  def bar(x, y, a:, b:, &block)
    puts a, b
    puts x, y
    block.call if block_given?
  end
  hook :bar,
       before: -> { puts "before hook" },
       after: -> { puts "after hook" }
end

Foo.new.bar(1, 2, a: 1, b: 2)

Foo.new.bar(1, 2, a: 1, b: 2) do
  puts "jajaja"
end

# Output: 
#  before hook
#  1
#  2
#  1
#  2
#  after hook
#  before hook
#  1
#  2
#  1
#  2
#  jajaja
#  after hook