Question

How to define a macro (this Q is somehow related to this Q and CashCow’s answer) which will expand to a different integer if this macro is used on different line in code?
I would like to be able to type:

X<1> _0;
X<1> _1;

after such def. I would like _0 and _1 to be of different types.

Answer 1

you can use something like this:

#define var(T,...) T<__VA_ARGS__,__LINE__> 

or if your only doing this for one know type:

#define var(x) T<(x),__LINE__> 

I suggest using __COUNTER__ instead of __LINE__ however, it allows the type to be globaly
unique, not just unique to the line.

EDIT: reread the question, what exactly do you mean by “different integer”? as in a different type or different initialization value?

template<typename T = int, const T nValue> class Integer
{
    T Value;
    Integer() : Value(nValue)
    {
    }

    operator T()
    {
        return Value;
    }
};

#define VI(x) Integer<__COUNTER__> x

or (This seems to be the one you want)

#define I(x) int x(__COUNTER__)