Using module eval to Define Instance Methods in a Ruby Gem to Enable Per Model Configuration
Using module eval to Define Instance Methods in a Ruby Gem to Enable Per Model Configuration In the last post, I mentioned that I wrote a small gem to post changes to ActiveRecord models to Twitter. In that version, the configuration was handled by a YAML file. I wanted to evolve the gem so that developers could switch Twitter accounts for each model. Basically, I wanted to able to the use the following: class Place { :username => alastrina_gem, :password => QQQQQQ } end After a bit of tinkering and searching, I decided to use the following code in my gem. ALASTRINA_CONFIGURATION_FILE = config/alastrina.yml module Alastrina def self.included(base) base.extend(ClassMethods) end module ClassMethods def alastrina hash module_eval do def configuration throw "Missing #{ALASTRINA_CONFIGURATION_FILE}" unless File.exists? ALASTRINA_CONFIGURATION_FILE @config ||= YAML::load(File.read(ALASTRINA_CONFIGURATION_FILE)) end if hash[:twitter] def send_to_twitter? true end eval...
