This is what boost variant serialization does. Robert Ramey Andrew Holden wrote:
Robert Ramey wrote:
Steven Watanabe wrote:
AMDG
niranjan bangera wrote:
union myunion {
uint32_t a; float t;
template <class Archive> void serialize(Archive & ar, const unsigned int file_version) {
ar & a; ar & t;
}
This is undefined behavior. a and t cannot both be valid at the same time.
LOL - makes me wonder if I'm even reading these emails.
One could do try:
struct myunion { union { uint32_t a; float t; } x; operator (uint32_t &)(){ // i forget the exact casting operator syntax return a; } operator(float &t)(){ return t; } template<class Archive> void serialize(Archive & ar, const unsigned int file_version){ ar & binary_object(sizeof(x), &x); } };
crude - but effective.
Robert Ramey
The best solutions would become more obvious if you know which type is valid at a higher level. For example, if you have a structure like this:
struct UnionWrapper { myunion the_union; bool is_float; /* Set to true if and only if the float member is used */
template <class Archive> void serialize (Archive &ar, unsigned int const version) { ar & is_float; /*Do this first so deserialization knows which union member to get. */
if (is_float) { ar & the_union.t; } else { ar & the_union.a; } } };