How to simulate Java-like annotations in Ruby?

Question

How to simulate Java-like annotations in ruby?

(We\'ll I have the answer, generalizing http://bens.me.uk/2009/java-style-annotations-in-ruby)

Answer 1

My requirement is

On a page I display a list of all instance_methods for a Class ABC, and there should be a 1 line description too with every method

Now I don' know if it is just me or storing the descriptions for all those methods with their names in a new table in the DB sounds "Super LAME"

Answer is - "Annotations"

Here's how I did it -

1. The module Annotations given by cibercitizen1
2. Code to include the module and activate the functionality in the desired class

Class abc.rb

class Abc
   extend Annotations
   create_annotation("_annotation")

 _annotation({:description=>"Info e-mail address"})
 def info_email
    APP_CONFIG['info_email']
 end

 _annotation({:description=>"Location of order"})
 def location
    unless self.order.blank?
      @location ||= self.order.location.description
    end
 end

3. Code to display the given descriptions (only, not the method name) through the annotation attribute hash for the collection of instance_methods, in the view which has access to the class Abc.

VIEW methods_list.html.erb

 
 
 
  
 <% default_description = "Description not specified" %>
  <% Abc.instance_methods.each do |method| %>
     
     <%= (Abc.annotations[method.to_sym].present?
     ?
     (Abc.annotations[method.to_sym][:_annotation][:description].blank?
     ? default_description :
     Abc.annotations[method.to_sym][:_annotation][:description])
     : default_description) %>
     

   <% end %> 
   

Hope it helps!