add before and after hooks

hooks.rb

module Hooks
  def before(*method_names, &block)
    to_prepend = Module.new do
      method_names.each do |name|
        define_method(name) do |*args, &blk|
          yield(name, *args)
          super(*args, &blk)
        end
      end
    end
    prepend to_prepend
  end
  def after(*method_names, &block)
    to_prepend = Module.new do
      method_names.each do |name|
        define_method(name) do |*args, &blk|
          super(*args, &blk)
          yield(name, *args)
        end
      end
    end
    prepend to_prepend
  end
end


class Example
  extend Hooks

  before :foo, :bar do |m,*a|
    puts "before #{m}(#{a.join(',')})"
  end

  after :bar do |m,*a|
    puts "after #{m}(#{a.join(',')})"
  end

  def foo(x)
    puts "in foo #{x}"
  end
  
  def bar
    puts "in bar"
  end
end

e = Example.new
e.foo 5
e.bar