Detecting and bypassing disabled RTTI

Some companies and libraries have specific requirements for their C++ code, such as successful compilation without RTTI.

In this small recipe, we'll not just detect disabled RTTI, but also write a Boost like library from scratch that stores information about types, and compares types at runtime, even without typeid.

Getting ready

Basic knowledge of C++ RTTI usage is required for this recipe.

How to do it...

Detecting disabled RTTI, storing information about types, and comparing types at runtime are tricks that are widely used across Boost libraries.

1. To do this, we first need to include the following header:

#include <boost/config.hpp> 

2. Let's first look at the situation where RTTI is enabled and the C++11 std::type_index class is available:

#if !defined(BOOST_NO_RTTI) \
    && !defined(BOOST_NO_CXX11_HDR_TYPEINDEX)

#include <typeindex>
using std::type_index;

template <class T>
type_index type_id() {
    return typeid(T);
}

3. Otherwise...