CODEWITHSUNDEEP
c++constructorfunctor
doubleflowseven
doubleflowseven

Reputation: 1

IDE thinks functor is a constructor?

I am trying to write an implementation of primms algorithm for a DSA class. There are some nuances to make the project a little trickier (some points cannot be reached by others based on the 'terrain' at that location) so I made a functor to get distances (edge weights). My functor looks like this 

class primms_distance{
            double operator ()(const primms_vertex &a, const primms_vertex &b){
                //ommitted for University honor code purposes
            }
        };

However, I later do the following (again simplified for honor code purposes) 

primms_vertex temp = priority_queue.top();
priority_queue.pop();
for(primms_vertex a : primms_vector){
    if(omitted && primms_vertex::primms_distance(a, temp) < a.distance)
}

This call to primms distance gets me the error 'no matching constructor for initialization of 'primms_vertex::primms_distance'. Does anyone know why this is happening? The functor is clearly defined as 'double operator ()' so Im not sure why this is happening, any help would be appreciated!

Upvotes: 0

Views: 64

Answers (1)

463035818_is_not_an_ai
463035818_is_not_an_ai

Reputation: 122585

You need an object to call a non-static member function. The compiler is right in expecting a call to the constructor first. Try this:

primms_vertex::primms_distance()(a, temp)
                            //^ constructor
                            //   ^ operator()

Upvotes: 2

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