hoangdangninh
7/12/2017 - 4:05 PM

From https://www.jimmycuadra.com/posts/metaprogramming-ruby-class-eval-and-instance-eval/

From https://www.jimmycuadra.com/posts/metaprogramming-ruby-class-eval-and-instance-eval/

metaprogramming.rb
content_copyfile_download
class Person
end

Person.class_eval do
  def say_hello
   "Hello!"
  end
end

jimmy = Person.new
jimmy.say_hello # "Hello!"

###############################################

class Person
end

Person.instance_eval do
  def human?
    true
  end
end

Person.human? # true