ruby​​/rails：如何確定是否包含模塊？

Question

使用我現有的解決方案在此擴展我的問題（ruby/rails: extending or including other modules），確定我的模塊是否包含在內的最佳方法是什麼？

我現在所做的是我在每個模塊上定義了實例方法，所以當它們包含一個方法將可用，然後我只在父模塊中添加一個捕獲器（method_missing()），這樣我就可以捕獲它們，如果它們不是包括在內。我的解決方案的代碼如下所示：

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 

所以在我的模型有：

# 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 

，然後我可以

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

我有沒有正確寫的嗎？或者，還有更好的方法？

Answer 1

如果我正確理解你的問題，你可以這樣做：

Man.included_modules.include?(Features)? 

例如：

module M 
end 

class C 
    include M 
end 

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

爲

C.included_modules 
    #=> [M, Kernel] 

其他方式：

爲@ Markan提到：

C.include? M 
    #=> true 

或：

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

或者只是：

C < M 
    #=> true