CODEWITHSUNDEEP
c++
Gilsho
Gilsho

Reputation: 63

Pointer to the same class but with different template type

I have the same class with different template type instantiation. Is it possible to point from one to another?

For example, compiling the following code

template <typename T>
class Base {
public:
    Base *p;
};


int main() {
    Base<int> a1;
    Base<float> a2;
    a1.p = &a2;

    return 0;
}

returns with

error: cannot convert ‘A<float>*’ to ‘Base<int>*’ in assignment
   a1.p = &a2;

Thanks!

Upvotes: 0

Views: 371

Answers (1)

Lukas-T
Lukas-T

Reputation: 11340

I have the same class with different template type instantiation.

Actually no, because a template is no class, but describes a family of classes. For more detailed information see the documentation

Base<int> and Base<float> are two different classes, even if they come from the same template, so the compiler is right in your example. You can't have a pointer that can point to both (except for void* which is not recommended).

Anothe possible solution as proposed by IInspectable would be std::variant of that can point to one or the the other like:

std::variant<Base<int> *, Base<float> *> ptr;

(or preferable with smart pointers instead of raw pointers)

Upvotes: 3

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