Alternatives to CRTP

Question

Suppose we have following class with virtual method:

struct icountable{
   virtual int count() = 0;

   bool empty(){
      return count() == 0;
   }
}

struct list : public icountable {
...
}

Now suppose this can be rewritten with CRTP. Should look more or less like:

template <typename T> 
struct icountable{
   bool empty(){
      return static_cast<T*>(this)->count() == 0;
   }
}

struct list : public icountable<list> {
...
}

Now suppose the class itself does not need to use empty() method. Then we can do something like this:

template <typename T> 
struct icountable : public T{
   bool empty(){
      return count() == 0;
   }
}

struct list_base{
...
}

typedef icountable<list_base> list;

My question is for third example. Is this what is called traits? Is there advantages / disadvantages if I use those?

It could be (and is) called "mixin", which is a term that existed in older OO languages and seems to apply here. I do not know if there is a better name for it. — Yakk - Adam Nevraumont, Oct 06 '15 at 13:54

score 0 · Accepted Answer · edited May 23 '17 at 12:14

0

As the comments say, this is the mix-in concept, and you can find informations about it here.

The traits are different and here you can find a basic example.

edited May 23 '17 at 12:14

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answered Oct 06 '15 at 14:12

sop

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Alternatives to CRTP

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