#include <iostream>
 
template<unsigned A>
struct Wrapper {
    int content[A];
    void foo() { };
};
 
#define WRAPPER_SWITCH_CASE(i) case i: Wrapper<i>().foo(); break;
 
int main(int argc, char *argv[])
{
    std::string arg = /*argv[1]*/"2"; // ...because here is online compiler >o<
    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;
}
 

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