Talk:Trait

Yes, this is indeed possible in C++ and is, in fact, used extensively in the C++ standard library (aka STL). For a prime example, look no further than std::string or the various pluggable memory allocators. The example given in the article appears to these eyes as one of a C programmer trying to make C++ do things like C and failing. To be more precise, if one is accessing people objects by iterator, why would a raw pointer to a person need to be manipulated in this way? In addition, what happens if the object must be accessed in multiple ways, e.g., exists in both a normal list and a sorted list (or multiple sorted lists). The C method falls down as there is no single pair of *next and *prev but rather multiple.

Don't get me wrong, C definitely has its uses. Its relative simplicity for one. However, C++'s generic algorithms and data structures should not be discarded so lightly.

--Miles Elam 20:26, 4 September 2012 (CEST)

The article is more about STL overhead. I personally don't like and don't use STL. I think following C++ implementation is as fast as implementation in C.

class ll_item;
 
class llist {
  public:
    void add(ll_item& p);
    void remove(ll_item& p);
 
    llist(void);
   ~llist();
};
 
class ll_item {
    friend llist;
  private:
    ll_item* next;
    ll_item* prev;
};
 
 
class person_item : public ll_item {
  protected:
    int age;
    const char* name;
 
  public:
    person_item(int age, const char* name);
};
 
class animal_item : public ll_item {
  protected:
    const char* name;
 
  public:
    animal_item(const char* name);
};
 
int main(int argc, char* argv[])
{
  person_item a(10, "Ben");
  person_item b(20, "Nora");
  person_item c(30, "John");
 
  animal_item x("Fifi");
  animal_item y("Bobika");
  animal_item z("Bill");
 
  llist l;
  l.add(b);
  l.add(c);
  l.add(a);
  l.add(x);
  l.add(y);
  l.add(z);
}

--jtulach 21:07, 11 September 2012 (CEST)