How can I add reflection to a C++ application?

Question

I\'d like to be able to introspect a C++ class for its name, contents (i.e. members and their types) etc. I\'m talking native C++ here, not managed C++, which has reflection

Answer 1

You need to look at what you are trying to do, and if RTTI will satisfy your requirements. I've implemented my own pseudo-reflection for some very specific purposes. For example, I once wanted to be able to flexibly configure what a simulation would output. It required adding some boilerplate code to the classes that would be output:

namespace {
  static bool b2 = Filter::Filterable::Register("MyObject");
} 

bool MyObj::BuildMap()
{
  Filterable::AddAccess("time", &MyObj::time);
  Filterable::AddAccess("person", &MyObj::id);
  return true;
}

The first call adds this object to the filtering system, which calls the BuildMap() method to figure out what methods are available.

Then, in the config file, you can do something like this:

FILTER-OUTPUT-OBJECT   MyObject
FILTER-OUTPUT-FILENAME file.txt
FILTER-CLAUSE-1        person == 1773
FILTER-CLAUSE-2        time > 2000

Through some template magic involving boost, this gets translated into a series of method calls at run-time (when the config file is read), so it's fairly efficient. I wouldn't recommend doing this unless you really need to, but, when you do, you can do some really cool stuff.