4tw_rake.rb

class MyAwesomeRake

  class Task

    attr_reader :dependencies, :description, :block

    def initialize(description, dependencies = [], &block)
      @dependencies = dependencies
      @description = description
      @block = block
    end

    def run(id)
      @dependencies.each do |d|
        possible_namespaces = possible_namespaces_for_id(id)
        p possible_namespaces
        possible_namespaces.each do |ns|
          possible_task_id = ns << ":" << d
          if MyAwesomeRake.task_exists?(possible_task_id)
            MyAwesomeRake.run possible_task_id
            break
          end
          raise Exception.new "Could not load dependency named '#{d}'\nDid research in following scopes: #{possible_namespaces.to_s}"
        end
      end
      @block.call if @block
    end

    def possible_namespaces_for_id(id)
      namespace = id.split(":")
      namespace.pop
      namespace = namespace.inject([]) { |memo, ns| memo << (memo + [ns]).join(":")}.reverse
      namespace << "" # add empty string for default search
    end

  end


  def self.run(identifier)
    task = @tasks[identifier.to_s]
    unless task == nil
      task.run(identifier.to_s)
    else
      raise Exception.new("Could not find task named '#{identifier}'\nUse MyAwesomeRake.print_tasks to print all tasks")
    end
  end


  def self.add_task(identifier, task)
    @tasks ||= {}
    @tasks[identifier.to_s] = task
  end


  def self.print_tasks
    @tasks.map do |id, task|
      puts "-- Task '#{id}' --\nDescription '#{task.description}'\nDependencies: #{task.dependencies}\n\n"
    end
  end

  def self.task_exists?(identifier)
    @tasks[identifier.to_s]
  end

end

def namespace(name)
  $namespace_stack ||= []
  $namespace_stack.push(name)
  $n = $namespace_stack.compact.join(":")
  yield
  $namespace_stack.pop
end

def task(identifier, &block)
  if identifier.is_a?(Hash) # check for dependencies
      id_with_namespace = [$n, identifier.keys.first].compact.join(":")
      dependencies = identifier.values.first.is_a?(Array) ? identifier.values.first : [identifier.values.first]
      dependencies = dependencies.map &:to_s
      task = MyAwesomeRake::Task.new $d, dependencies, &block
      MyAwesomeRake.add_task(id_with_namespace, task)
  else
    id_with_namespace = [$n, identifier].compact.join(":")
    task = MyAwesomeRake::Task.new $d, &block
    MyAwesomeRake.add_task(id_with_namespace, task)
  end
  $d = nil
end

def desc(description)
  $d = description
end