gistfile1.rb

class SomeApp 

  def some_function(a)
    puts a
    Views::Index.instance_eval do
      attr_reader :a
      set_instance_variable(:@a, a)
    end
  end 
  
  module Views
  
    class Index < Mustache
    
      #this shouldn't break
      puts a
    
      def some_other_function(b)
        puts b
      end
    end
  end
end