ruby-on-rails - 覆盖类和实例方法的 method_missing？

Question

我正在尝试编写一个通用模块，以将用于动态方法创建的 method_missing 模式应用于我的某些 Rails 模型。这些模型既有类方法也有实例方法。虽然我可以相当直接地为任一类案例编写模块:

  module ClassVersion
    extend ActiveSupport::Concern

    module ClassMethods
      def method_missing(meth, *args, &block)
        if meth.to_s =~ /^(.+)_async$/
          Async::handle_async self, $1, *args, &block
        else
          super meth, *args, &block
        end
      end

      # Logic for this method MUST match that of the detection in method_missing
      def respond_to_missing?(method_name, include_private = false)
        Async::async?(method_name) || super
      end
    end
  end

或实例案例:

  module InstanceVersion
    extend ActiveSupport::Concern

    def method_missing(meth, *args, &block)
      if meth.to_s =~ /^(.+)_async$/
        Async::handle_async self, $1, *args, &block
      else
        super meth, *args, &block
      end
    end

    # Logic for this method MUST match that of the detection in method_missing
    def respond_to_missing?(method_name, include_private = false)
      Async::async?(method_name) || super
    end
  end

...我似乎无法在同一类中支持这两种情况。有没有更好的方法来覆盖 method_missing 以支持这两种情况？我在 Rails 3.2 上....

Answer 1

您要实现的目标非常简单，同时又不寻常。 ActiveSupport::Concern 使您可以定义嵌套的 ClassMethods 模块，该模块在 included 模块 Hook 上扩展基类。通常这很方便，因为您不想使用相同的方法扩充类及其实例。

您需要做的是停止使用 ActiveSupport::Concern 并编写 included 钩子(Hook)来满足您的特定需求:

module AsyncModule
  def method_missing(meth, *args, &block)
    if meth.to_s =~ /^(.+)_async$/
      Async::handle_async self, $1, *args, &block
    else
      super meth, *args, &block
    end
  end

  # Logic for this method MUST match that of the detection in method_missing
  def respond_to_missing?(method_name, include_private = false)
    Async::async?(method_name) || super
  end

  private

  def self.included(base)
    base.extend self
  end
end