Boost C++ Libraries

Description

BOOST_TYPE_INDEX_REGISTER_RUNTIME_CLASS generates a virtual function in the current class that, when combined with the supplied base class information, allows boost::typeindex::runtime_cast to accurately convert between dynamic types of instances of the current class.

BOOST_TYPE_INDEX_REGISTER_RUNTIME_CLASS also adds support for boost::typeindex::type_id_runtime by including BOOST_TYPE_INDEX_REGISTER_CLASS. It is typical that these features are used together, but in the event that BOOST_TYPE_INDEX_REGISTER_CLASS is undesirable in the current class, BOOST_TYPE_INDEX_IMPLEMENT_RUNTIME_CAST is provided.

Example:

struct base1 {
    BOOST_TYPE_INDEX_REGISTER_RUNTIME_CLASS(BOOST_TYPE_INDEX_NO_BASE_CLASS)
    virtual ~base1();
};

struct base2 {
    BOOST_TYPE_INDEX_REGISTER_RUNTIME_CLASS(BOOST_TYPE_INDEX_NO_BASE_CLASS)
    virtual ~base2();
};

struct derived1 : base1 {
    BOOST_TYPE_INDEX_REGISTER_RUNTIME_CLASS((base1))
};

struct derived2 : base1, base2 {
    BOOST_TYPE_INDEX_REGISTER_RUNTIME_CLASS((base1)(base2))
};

...

base1* pb1 = get_object();
if(derived2* pb2 = boost::typeindex::runtime_cast<derived2*>(pb1)) {
    assert(boost::typeindex::type_id_runtime(*pb1)) == boost::typeindex::type_id<derived2>());
}