Question

使用我现有的解决方案扩展我的问题（ruby/rails: extending or including other modules），确定我的模块是否包含在内的最佳方法是什么？

我现在所做的是我在每个模块上定义了实例方法，所以当它们被包含时，一个方法可用，然后我只是将一个捕获器（method_missing()）添加到父模块中，这样我就能抓住它它们不包括在内。我的解决方案代码如下：

module Features
  FEATURES = [Running, Walking]

  # include Features::Running
  FEATURES.each do |feature|
    include feature
  end

  module ClassMethods
    # include Features::Running::ClassMethods
    FEATURES.each do |feature|
      include feature::ClassMethods
    end
  end

  module InstanceMethods
    def method_missing(meth)
      # Catch feature checks that are not included in models to return false
      if meth[-1] == '?' && meth.to_s =~ /can_(\w+)\z?/
        false
      else
        # You *must* call super if you don't handle the method,
        # otherwise you'll mess up Ruby's method lookup
        super
      end
    end
  end

  def self.included(base)
    base.send :extend, ClassMethods
    base.send :include, InstanceMethods
  end
end

# lib/features/running.rb
module Features::Running
  module ClassMethods
    def can_run
      ...

      # Define a method to have model know a way they have that feature
      define_method(:can_run?) { true }
    end
  end
end

# lib/features/walking.rb
module Features::Walking
  module ClassMethods
    def can_walk
      ...

      # Define a method to have model know a way they have that feature
      define_method(:can_walk?) { true }
    end
  end
end

所以在我的模特中我有：

# Sample models
class Man < ActiveRecord::Base
  # Include features modules
  include Features

  # Define what man can do
  can_walk
  can_run
end

class Car < ActiveRecord::Base
  # Include features modules
  include Features

  # Define what man can do
  can_run
end

然后我可以

Man.new.can_walk?
# => true
Car.new.can_run?
# => true
Car.new.can_walk? # method_missing catches this
# => false

我写得对吗？或者有更好的方法吗？

Answer 1

如果我理解你的问题，你可以这样做：

Man.included_modules.include?(Features)?

例如：

module M
end

class C
  include M
end

C.included_modules.include?(M)
  #=> true

作为

C.included_modules
  #=> [M, Kernel]

其他方式：

正如@Markan所说：

C.include? M
  #=> true

或：

C.ancestors.include?(M)
  #=> true

或只是：

C < M
  #=> true

ruby / rails：如何确定是否包含模块？

1 个答案: