I have many concrete-structs and I want to designate fields as optional (present or not-present). Just wondering what ideas people have for achieving this. Here is an example struct (fields can be other structs as well, even vectors of structs):
struct LogonMessage_t
{
Header_t header; // this points to another struct containing all primitives
std::string username;
std::string password;
std::vector<LogonOption_t> LogonOptions;
int subaccountid;
std::string Text;
}
I'd like to default all fields to not-present and enable them one by one, perhaps in their setters. Since these structs are generated, a generic method would be preferable.
My ideas so far are:
- Bitmap of fields indicating if a field is set or not
- Use sentinel values ("\0" for std::string, -1 for int, -1.0f for float
- Some kind of template container/proxy encapsulating each field to indicate if it's set or not, any ideas? I think this might be the best approach.
Btw, using maps or other STL containers to encapsulate the fields won't work here, they need to be concrete structs.