Very simple rtti

rtti.cpp

#include <assert.h>


struct rtti_t {

    template <typename type_t>
    bool is_a() const {
        return _tag == type_t::tag;
    }
    
    template <typename type_t>
    type_t & cast() {
        assert(is_a<type_t>());
        return *static_cast<type_t*>(this);
    }
    
    template <typename type_t>
    const type_t & cast() const {
        assert(is_a<type_t>());
        return *static_cast<const type_t*>(this);
    }
    
protected:

    rtti_t(const int tag)
        : _tag(tag)
    {
    }

    const int _tag;
};


struct test1_t : public rtti_t {

    test1_t() : rtti_t(tag) {}

    int foo;
    static const int tag;
};


struct test2_t : public rtti_t {

    test2_t() : rtti_t(tag) {}

    static const int tag;
};


int main() {

    rtti_t *x = new test1_t;
    if (x->is_a<test2_t>()) {
        return 0;
    }
    x->cast<test1_t>().foo = 1;
    return 1;
}