Monkey patch for rake to save result of task that is depended

rake_monkey_patch.rb

# namespace :result do
#   task :foo do
#     "Result of foo"
#   end
# 
#   task bar: :foo do
#     "Result of bar"
#   end
# end
# 
# task test: :"result:bar" do |task|
#   puts task.dependency_result # => "Result of bar"
#   puts task.dependency_result("result:foo") # => "Result of foo"
# end

module Rake
  class Task
    attr_reader :result

    alias_method :old_reenable, :reenable
    alias_method :old_enhance, :enhance

    def enhance(deps=nil, &original_action)
      wrapped_action = -> (task, args) {
        @result = original_action.call(task, args)
      }

      old_enhance(deps, &wrapped_action)
    end

    def reenable
      old_reenable
      @result = nil
    end

    def dependency_result(name = nil)
      task = if name
               all_prerequisite_tasks.find { |t| t.to_s == name }
             else
               prerequisite_tasks.first
             end

      task&.result
    end
  end
end