Question

我正在尝试编写一个通用模块，将方法创建模式应用于我的一些Rails模型。这些模型具有类方法和实例方法。虽然我可以相当直接地为一个类案例编写一个模块：

  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

......我似乎无法在同一个班级支持这两种情况。有没有更好的方法来覆盖method_missing，以便支持这两种情况？我在Rails 3.2 ....

Answer 1

你想要达到的目标非常简单，同时又不同寻常。 ActiveSupport::Concern使您可以定义嵌套ClassMethods模块，该模块正在included模块挂钩上扩展基类。通常这很方便，因为您不希望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挂钩以满足您的特定需求：

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

Answer 2

您是否尝试过以下

  module ClassAndInstanceVersion
    extend ActiveSupport::Concern

    def method_missing(meth, *args, &block)
      self.class.method_missing(meth, *args, &block)
    end

    def respond_to_missing?(method_name, include_private = false)
      self.class.respond_to_missing?(method_name, include_private)
    end

    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

覆盖类和实例方法的method_missing？

2 个答案: