How to stop template class for a type

Question

Hi

How to avoid error in attached code ?

I just want to avoid the template class for int... How to do same ?
https://code.sololearn.com/coV5FijP5pN9/?ref=app

Answer 1

There are several ways to do this. For such a simple case, you can just use static_assert to assert that T is not int
https://code.sololearn.com/ct9GQv6sPd8O/?ref=app

There are a lot of cases where you have several partial specialisations of the template, in which case you might want to choose one specialization over another. There, a static_assert won't be enough. Before C++ 20, the way to do this was to use std::enable_if
https://code.sololearn.com/cTmooXtM9MRO/?ref=app

After C++ 20, you can use template constraints which offer a much better syntax and error message (compared to the mess that std::enable_if emits on failure)
https://code.sololearn.com/ctWvsPop4hY8/?ref=app

std::enable_if :-
https://en.cppreference.com/w/cpp/types/enable_if

Template constraints:
https://en.cppreference.com/w/cpp/language/constraints

Answer 2

I don't know if = delete syntax is available for classes/structures, I would do as follows:

template<>
struct myClass<int> {

private:

myClass() {}

};

This way you could not instantiate myClass<int> objects.

For static functions you could simply leave the specialization empty, so display() wouldn't exist for myClass<int>.

Answer 3

Thanks XXX and OrHy3