method_missing.rb

class DynamicProxy
  def initialize(subject)
    @subject = subject
  end

  def method_missing(method_name, *args, &block)
    if @subject.respond_to?(method_name)
      @subject.send(method_name, *args, &block)
    else
      super
    end
  end

  def respond_to_missing?(method_name, include_private = false)
    @subject.respond_to?(method_name, include_private) || super
  end
end


class RealSubject
  def existing_method
    "This method exists!"
  end
end

real_object = RealSubject.new
proxy = DynamicProxy.new(real_object)

puts proxy.existing_method  # Outputs: "This method exists!"
puts proxy.non_existing_method  # Raises NoMethodError (trick to handle)