Ruby gem扩展类具有在块中定义的方法

Question

I am creating a gem and wanted to be able to modify an ActiveRecord object by creating attribute getters and setters dynamically to a serialized attribute. For example:

class User
  has_serialized :setting do |config|
    config.define :notify_by_email, default: true
    config.define :notify_by_phone, default: true
  end
end

user = User.new
user.notify_by_email? # true
user.notify.by_phone? # true
user.notify_by_email = false
user.notify_by_phone = false
user.notify_by_email? # false
user.notify.by_phone? # false

I realize that I will need to extend ActiveRecord with a module containing the method has_serialized and that I will need to use define_method to add the custom getters and setters, however I can't figure out how to combine the two using the block syntax I want for definition. Any ideas?

Answer 1

You can create a class that extends hash used to capture your parameters then execute the block using the class. Once finished, you can iterate over your capture performing define method. Here is an example:

class Initializer < Hash
  def define(settings, options = {})
    self[setting] = options
  end
end

module ClassMethods
  def has_serialized(name, &block)
    initializer = Initializer.new
    block.call(initializer)
    initializer.each do |method, options|
      define_method "#{method}?" do
        ...
      end
      define_method "#{method}=" do |value|
        ...
      end
    end
  end
end