CODEWITHSUNDEEP
c++templatesfunctor
Robo
Robo

Reputation: 311

Functor and templates

It is possible to distinguish when template parameter in functor represents an object or a pointer to object?

class Comparator
{
    public:

            template <typename Object>
            bool operator() ( const Object &o1, const Object &o2 ) const
            {
                   return ( o1.getID() < o2.getID() );
            }

            template <typename Object>
            bool operator() ( const Object *o1, const Object *o2 ) const
            {
                   return ( o1->getID() < o2->getID() );
            }
};

Objects or pointers are stored in generic container List, that should be sorted using the Comparator class

int main()
{
   List <Object *> objects1;
   std::sort(objects1.begin(), objects1.end(), Comparator()); 
   List <Object> objects2;
   std::sort(objects2.begin(), objects2.end(), Comparator());
);

Currently I am using two comparators (Comparator1, Comparator2) but I do not find it comfortable...

Upvotes: 1

Views: 454

Answers (2)

LumpN
LumpN

Reputation: 139

You could templatetify the Comparator itself:

template<typename Object>
class Comparator {
    public:

        bool operator()(const Object &o1, const Object &o2) const {
            return (o1.getID() < o2.getID());
        }

        bool operator()(const Object *o1, const Object *o2) const {
            return (o1->getID() < o2->getID());
        }
};
int main() {
    std::vector objects1;
    std::sort(objects1.begin(), objects1.end(), Comparator<Object> ());
    std::vector objects2;
    std::sort(objects2.begin(), objects2.end(), Comparator<Object> ());
    return 0;
}

This way it doesn't even generate two separate comparators!

Upvotes: 4

John Dibling
John Dibling

Reputation: 101456

Given your architecture (one list of Objects, another of Object*s) you really have no alternative.

Do you really need two lists?

Upvotes: 0

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