C++ template instantiation: Avoiding long switches

Question

I have a class depending on an integer template parameter. At one point in my program I want to use one instantiation of this template, depending on a value of this paramet

Answer 1

just use macros!

template
struct Wrapper {
    int content[A];
    void foo() { };
};

#define WRAPPER_SWITCH_CASE(i) case i: Wrapper().foo(); break;

int main(int argc, char *argv[])
{
    std::string arg = argv[1];
    int arg_int = std::stoi(arg);

    switch (arg_int) {
        WRAPPER_SWITCH_CASE(1)
        WRAPPER_SWITCH_CASE(2)
        WRAPPER_SWITCH_CASE(3)
        default: return 1;
    };

    return 0;
}

(live example)

But as you know, macros are harmful; I think Wrapper should be allocate content at runtime, not template.