Rubyメタプログラミングの注目すべき点

 class_eval 'def use_relative_model_naming?; true; end', __FILE__, __LINE__

 # from activesupport/lib/active_support/core_ext/string/output_safety.rb
 UNSAFE_STRING_METHODS.each do |unsafe_method|
  if 'String'.respond_to?(unsafe_method)
  class_eval <<-EOT, __FILE__, __LINE__ + 1
   def #{unsafe_method}(*args, &block) # def capitalize(*args, &block)
   to_str.#{unsafe_method}(*args, &block) # to_str.capitalize(*args, &block)
   end # end

   def #{unsafe_method}! (*args) # def capitalize!(*args)
   @dirty = true # @dirty = true
   super # super
   end # end
  EOT
  end
 end

 # bad
 def method_missing?(meth, *args, &block)
  if /^find_by_(? <prop>. *)/ =~ meth
  # ... lots of code to do a find_by
  else
  super
  end
 end

 # good
 def method_missing?(meth, *args, &block)
  if /^find_by_(? <prop>. *)/ =~ meth
  find_by(prop, *args, &block)
  else
  super
  end
 end

 # best of all, though, would to define_method as each findable attribute is declared