C++ syntax help, using templates - c++

Question

It is probably some stupid syntax mistake, i have the following class written in h file
#include "IGenticSolverHelper.h"
template <class T>
class GenericGeneticSolver
{
public:
GenericGeneticSolver(IGenticSolverHelper<T>& helper, int generationSize) : mSolverHelper(helper)
{
mSolverHelper.GenerateFirstGeneration(0, generationSize, currentGeneration);
}
private :
vector<T> currentGeneration;
IGenticSolverHelper<T>& mSolverHelper;
};
And then the following code :
#include "IGenticSolverHelper.h"
#include "GenericGeneticSolver.h"
class HelperImpl : IGenticSolverHelper<int>
{
public:
void GenerateFirstGeneration(const int seed,const int generationSize, vector<int>& firstGeneration)
{
}
void Crossover(const int& father,const int& mother, int& son)
{
}
void Mutate(const int& orignal, int& mutated)
{
}
float Cost(int& solution)
{
}
};
int main()
{
int a =5;
GenericGeneticSolver<int> mySolver(HelperImpl,a);
}
And i get the following error when i compile :
error C2061: syntax error : identifier 'a'
if i will change the line to :
GenericGeneticSolver<int> mySolver(HelperImpl);
it will compile, though the constructor expect 2 arguments, and will get the following warning :
warning C4930: 'GenericGeneticSolver<T> mySolver(HelperImpl)': prototyped function not called (was a variable definition intended?)
And to add to the oddness, when i put a break point on this line, he won't stop there.
What am i doing wrong, i just trying to create an instance of GenericGeneticSolver

Answer 1

Take a look at this line:
GenericGeneticSolver<int> mySolver(HelperImpl,a);
The compiler is confused about what you're trying to do here because HelperImpl is the name of a type, while a is the name of an object. The compiler thinks what you're doing is trying to prototype a function named mySolver that takes in a parameter of type HelperImpl and a parameter of type a, but then gets stuck because it doesn't know of any types named a.
If you remove a, you get this:
GenericGeneticSolver<int> mySolver(HelperImpl);
This is a perfectly legal prototype of a function called mySolver that takes an argument of type HelperImpl and returns a GenericGeneticSolver<int>. The warning you're getting is the compiler telling you that you might not have meant to make this a prototype, since it somewhat looks like an instantiation of a variable named mySolver but isn't.
Since I assume that you're trying to instantiate an object of type GenericGeneticSolver<int> here, you probably want to instantiate a HelperImpl and then pass that object into the constructor, like this:
HelperImpl hi;
GenericGeneticSolver<int> mySolver(hi, a);
Hope this helps!