Crake - Cursed Ruby make. Demonstrates why class variables aren't recommended, I guess

decorated_task.rb

#--------------------------------------------------
# fake Rake
#--------------------------------------------------
module TaskRunner
  Task = Data.define *%i| name reqs recipes | do
    @@tasks = {}
    def run
      reqs.each { @@tasks[it]&.run }
      recipes.each { |recipe| recipe.call(self) }
      @@tasks.delete(name) # Don't repeat this Task
    end
  end
  
  END {
    (@@tasks[ARGV[1]] || @@tasks.each_value.first)&.run
  }
  
  private module_function def task(arg, &recipe)
    case arg
    when Hash
      name, reqs = arg.first
    when String, Symbol
      name = arg
    end

    @@tasks[name] ||= Task[name:, reqs: Array(reqs), recipes: Array(recipe)]
  end

  def self.[](...) = @@tasks.[](...)
end

# Bring the above "DSL" to the top-level
# (I could use `include` but that would polute the class vars of everything)
extend TaskRunner

#------------------------------------------------------------------------------
# Logging tasks
# - - -
#   1. Prepending a module  --  the modern way to monkey patch.
#      Also notice how `super` is super awesome!
#
module LoggingTaskOverride
  def task(...)
    super do |t|
      puts "--- Running #{t.name} ---"
      yield t
      puts
    end
  end
end

TaskRunner.prepend LoggingTaskOverride

# - - -
#   2. Intercepting Tasks' "recipes" Array's #each
#      to yield a phantom first action
#
module LoggingTaskTrappingArrayEach
  module PrependHack
    def each
      yield -> t { puts ">>> Running \e[36m#{t.name}\e[0m's actions <<<" }
      super
    end
    alias_method(:save_each, :each)
  end

  def run
    recipes.extend(PrependHack)
    PrependHack.remove_method(:each)
    super
  end
end

TaskRunner::Task.prepend LoggingTaskTrappingArrayEach

#------------------------------------------------------------------------------
# fake tasks
#
task 'three' => ['one', 'two'] do |t|
  puts "I run after one and two!"
end

task 'one' => ['before_one'] do |t|
  puts "One!"
end

task 'two' do |t|
  puts "Two!"
end

task 'before_one' do |t|
  puts "Let's go!"
end

__END__
puts "\e[32m---"
# pp((123).task('kek') { puts 'lol' })
cvar_tasks = -> o { o.class_variable_get(:@@tasks) }
p cvar_tasks[singleton_class]  rescue puts "not in singleton_class"
p cvar_tasks[TaskRunner]       rescue puts "not in TaskRunner"
p cvar_tasks[TaskRunner::Task] rescue puts "not in TaskRunner::Task"
p cvar_tasks[Integer]          rescue puts "not in Integer"
p cvar_tasks[Object]           rescue puts "not in Object"
puts "---\e[0m"