class_name_inside_a_proc.rb

module Kernel
  def singleton_class
    class << self
      self
    end
  end
end


class Human
  proc = lambda { puts 'proc says my class is ' + self.name.to_s }

  singleton_class.instance_eval do
    define_method(:lab)  do 
      proc.call
    end
  end
end

class Developer < Human
end

Human.lab # class is Human
Developer.lab # class is Human ; oops

# The fix is to use instance_exec

class Human
  proc = lambda { puts 'proc says my class is ' + self.name.to_s }

  singleton_class.instance_eval do
    define_method(:lab)  do 
      self.instance_exec &proc
    end
  end
end

class Developer < Human
end

Human.lab # class is Human
Developer.lab # class is Human ; oops