ruby-on-rails - 开发重新加载后 Rails 单例变空

Question

在我的 Rails 应用程序中，我决定使用单例创建某种工厂来正确获取对象。

config/initializers/registry.rb:

registry = Registry.instance

registry.define_lazy :period_predictor do
  PeriodPredictor.new(NotificationBuilder.new, 28, 4, 3)
end

registry.define_lazy :notification_sender do
  NotificationSender.new
end

lib/registry.rb:

# Registry class which is singleton and stores values.
class Registry
  include Singleton


  # Define simple value. Like a constant.
  #
  # @param key [Symbol]
  # @param value
  def define(key, value)
    container[key] = value
  end


  # Define value (block required) which will be calculated when it will be need.
  # It will calculate it every time when it will be needed.
  #
  # @param key [Symbol]
  # @param block [Proc]
  def define_lazy(key, &block)
    container[key] = LazyValue.new(&block)
  end


  # Get value.
  #
  # @param key [Symbol]
  #
  # @return
  def get(key)
    value = container[key]
    if value.is_a?(LazyValue)
      value = value.call
    end

    value
  end


  # Get value (hash access).
  #
  # @param key [Symbol]
  #
  # @return
  def [](key)
    get(key)
  end


  # Export all the values.
  # Replacing values of returned hash won't change registry.
  #
  # @return [Hash]
  def export
    container.clone
  end


  # Import hash data to registry
  #
  # @param data [Hash]
  def import(data)
    data.each do |key, value|
      @container[key] = value
    end
  end


  private

  # Get container.
  #
  # @return [Hash]
  def container
    @container ||= {}
  end


  # Class to store lazy value.
  class LazyValue
    def initialize(&block)
      @block = block
    end

    def call
      @block.call
    end
  end
end

生产中一切正常。但是当我更改某些内容(甚至在某处添加空间)时，我无法再在 Controller 中从单例获取数据。

Registry.instance 成为注册表的新实例并且Registry.instance[:period_predictor] 变为 nil

当我放弃单例并创建类方法时，也会发生同样的事情。

只有当我关闭单例并创建一个常量时，它才不会执行此操作:

registry = Registry.new

registry.define_lazy :period_predictor do
  PeriodPredictor.new(NotificationBuilder.new, 28, 4, 3)
end

registry.define_lazy :notification_sender do
  NotificationSender.new
end

REGISTRY = registry

Rails 版本 4.2.5.1

有人知道为什么会发生这种情况吗？

Answer 1

我发现，发生这种情况是因为 Rails 刷新了自动加载的常量。 http://guides.rubyonrails.org/autoloading_and_reloading_constants.html#constant-reloading

我在初始化程序的开头添加了一行 require "#{Rails.root}/lib/registry"，一切正常。