Use helpers during the construction

[ilyaraz]

Need to use the code like below instead of "exponential" case analysis in the wrapper.

#include <iostream>
#include <memory>

class Base {
public:
    virtual void impl() = 0;

    virtual ~Base() {}
};

template<bool u, bool v> class Derived : public Base {
public:
    void impl() {
        std::cout << u << " " << v << std::endl;
    }
};

class Factory {
public:
    static std::shared_ptr<Base> construct(bool u, bool v) {
        if (u) {
            return construct_1<true>(v);
        }
        else {
            return construct_1<false>(v);
        }
    }
private:
    template<bool u> static std::shared_ptr<Base> construct_1(bool v) {
        if (v) {
            return construct_2<u, true>();
        }
        else {
            return construct_2<u, false>();
        }
    }

    template<bool u, bool v> static std::shared_ptr<Base> construct_2() {
        return std::shared_ptr<Base>(new Derived<u, v>);
    }
};

int main() {
    std::shared_ptr<Base> x = Factory::construct(false, true);
    x->impl();
    return 0;
}

[ludwigschmidt]

Yes, that's roughly what I meant when we talked about how to integrate the second distance function. The helper function construction_helper is basically already one level of this, but you can refactor it to make it better. Let's wait until we are going to add the next case to construct_table and refactor things then.

BTW, not sure if we need shared_ptr for this. unique_ptr should be sufficient and also semantically what we want.

[ludwigschmidt]

Wrapper constructions was refactored in ba35a64 .