How do I access options passed to an acts_as plugin (ActiveRecord decorator) from instance methods?

Question

At the moment I store each option in its own class attribute but this leads to hard to read code when I need to access the passed options from instance methods.

For example if I pass a column name as an option I have to use self.send(self.class.path_finder_column) to get the column value from an instance method.

Notice I have prefixed the class attribute with the name of my plugin to prevent name clashes.

Here is a simple code example of a plugin which is passed an option, column, which is then accessed from the instance method set_path. Can the getters/setters be simplified to be more readable?

# usage: path_find :column => 'path'

module PathFinder    
  def path_finder(options = {})
    send :include, InstanceMethods

    # Create class attributes for options 
    self.cattr_accessor :path_finder_column
    self.path_finder_column = options[:column]

    module InstanceMethods
      def set_path        
        # setter
        self.send(self.class.path_finder_column + '=', 'some value')
        # getter
        self.send(self.class.path_finder_column)
      end
    end
  end 
end

ActiveRecord::Base.send :extend, PathFinder

Answer 1

You can generate all those methods at runtime.

module PathFinder
  def path_finder(options = {})

    # Create class attributes for options 
    self.cattr_accessor :path_finder_options
    self.path_finder_options = options

    class_eval <<-RUBY
      def path_finder(value)
        self.#{options[:column]} = value
      end

      def path_finder
        self.#{options[:column]}
      end
    RUBY
  end
end

ActiveRecord::Base.send :extend, PathFinder

Unless you need to store the options, you can also delete the lines

self.cattr_accessor :path_finder_options
self.path_finder_options = options

Note that my solution doesn't need a setter and a getter as long as you always use path_finder and path_finder=. So, the shortest solution is (assuming only the :column option and no other requirements)

module PathFinder
  def path_finder(options = {})

    # here more logic
    # ...

    class_eval <<-RUBY
      def path_finder(value)
        self.#{options[:column]} = value
      end

      def path_finder
        self.#{options[:column]}
      end
    RUBY
  end
end

ActiveRecord::Base.send :extend, PathFinder

This approach is similar to the one adopted by acts_as_list and acts_as_tree.