metaprogramming - result of 'self' in ruby module -

module cnblog2jekyll   class << self     attr_accessor :username       [:archive_links, :article_links].each |method_name|       define_method method_name         instance_value = instance_variable_get(("@" + method_name.to_s).to_sym)         instance_value ? instance_value : send("get_" + method_name.to_s)         # @archive_links ? @archive_links : get_archive_links       end     end      binding.pry      def test       binding.pry     end     end end 

please ignore meaning of part code , mind place of 'binding.pry'.

here comes question: type in 'self' in pry console @ place of 'binding.pry', , give result:

from: /home/yanying/cnblog2jekyll/lib/cnblog2jekyll.rb @ line 20 :      15:         instance_value = instance_variable_get(("@" + method_name.to_s).to_sym)     16:         instance_value ? instance_value : send("get_" + method_name.to_s)     17:         # @archive_links ? @archive_links : get_archive_links     18:       end     19:     end  => 20:     binding.pry     21:      22:     def test     23:       binding.pry     24:     end     25:   [1] pry(#<class>)> self => #<class:cnblog2jekyll> [2] pry(#<class>)> self.class => class [3] pry(#<class>)> self.ancestors => [#<class:cnblog2jekyll>, module, object, pp::objectmixin, kernel, basicobject] [4] pry(#<class>)>  => true [2] pry(main)> cnblog2jekyll.test  from: /home/yanying/cnblog2jekyll/lib/cnblog2jekyll.rb @ line 23 cnblog2jekyll.test:      22: def test  => 23:   binding.pry     24: end  [1] pry(cnblog2jekyll)> self => cnblog2jekyll [2] pry(cnblog2jekyll)> self.class => module [3] pry(cnblog2jekyll)> self.ancestors => [cnblog2jekyll] [4] pry(cnblog2jekyll)>  

so, question is: why first result of 'self' 'class'? second of "module"? what's magic here?

since using class << self, open self singleton class, , methods inside redefine methods of current self, in case module cnblog2jekyll

if had:

class cnblog2jekyll   def foo    end    class << self     def bar      end   end end 

and called cnblog2jekyll.new.bar undefined_method, because bar specified class method, not object method. in case, methods module methods, because class << self inside module block.

check out this question class << self idiom , this article it.