Generating a configuration parser in ruby, like chef or others

gistfile1.rb

require "erb"

class BigIpConfigurator 
  @@resources = {} # Hash with all the resources defined

  # Define a resource, adding it to the list
  def self.resource(name, defaults, &block)
    @@resources[name] = { 
      :defaults => defaults, 
      :block => block
    }
  end

  attr_reader :resources, :environment_name

  def initialize
    @properties_context=[]
    @environment_name=""
  end

  
  # The magick method!!!
  def method_missing(meth, *args)
    # Check if a resource is defined, and if it is, try to load it.
    if @@resources.include?(meth) 
      # Generate a new context for the properties with the defaults for 
      # this resource type
      defaults = @@resources[meth][:defaults]
      
      @properties_context.push(defaults)
      begin     
        yield # Load the properties
      ensure  
        properties = @properties_context.pop
      end
      
      # Implements the posibility of define a name template
      id = args.first
      if !defaults[:name_template]
        name = id 
      else
        name = ERB.new(properties[:name_template]).result(binding)
      end 

      # Call the block that implements the resource 
      @@resources[meth][:block].call(name, properties)
    
    # Load each of the properties if we are defining a resource
    elsif ! @properties_context.empty? and @properties_context.last.include?(meth)
      case args.size
      when 0 
         @properties_context.last[meth] = true
      when 1
         @properties_context.last[meth] = args.first
      else
         @properties_context.last[meth] = args
      end       
    else
      #Kernel.method_missing
      super
      #raise "Method missing: #{meth}"
    end
  end

  def load_config(str)
    self.instance_eval(str)
  end

  def environment(enviroment_name, &block)
    @environment_name = enviroment_name
    yield
  end
  
  # String class resource definition
  resource :string_class, { 
    :members => [],
    :name_template => 'string_class_<%= id %>'
    } do |name, properties|
      puts name 
      puts properties[:members]
  end
  
end

b = BigIpConfigurator.new
  
b.load_config %q{
environment "qa1" do
  string_class "something" do  
      name_template 'string_class_<%= id %>_<%= @environment_name %>'
      members 'a', 'e', 'i'
  end
end 
}