Question

I want to have a container (let’s say an std::vector) that would hold various inherited types, and would instantiate them,.i.e. vector of classes –> vector of objects.

For instance:

class A{};

class B: public class A
{};

class C: public class A
{};

void main()
{
    std::vector<of inherited A types> typesVec;
    std::vector<A*> objectsVec;

    typesVec.push_back(class B);
    typesVec.push_back(class C);

    for (int i = 0; i < typesVec.size(); i++)
    {
        A* pA = new typesVec.at(i);
        objectsVec.push_back(pA);
    }

}

Thanks in advance..

Answer 1

This isn’t possible in C++ (at least not directly). I can see this happening in a language that has reflection, but C++ doesn’t.

What you can do instead is create a factory or simply methods that create objects of the specified type.

Instead of having a vector of types, you’d have a vector of object generators (close enough, right?):

class A{};

class B: public class A
{};

class C: public class A
{};

struct AFactory
{
    virtual A* create() { return new A; }
};
struct BFactory : AFactory
{

    virtual A* create() { return new B; }
};
struct CFactory : AFactory
{

    virtual A* create() { return new C; }
};

//...

typesVec.push_back(new BFactory);
typesVec.push_back(new CFactory);

for (int i = 0; i < typesVec.size(); i++)
{
    A* pA = typesVec.at(i)->create();
    objectsVec.push_back(pA);
}