Re: Trick to prevent conversion

I think this is a pretty good way of doing it. One way of making it
a bit more elegant/generic would be something like this
(warning - untested):

template <typename W, class TAG> class TypeWrapper {
  W myWrapped;
public:
  explicit TypeWrapper(W wrapped) : myWrapped(wrapped) {}
  W getWrapped() { return myWrapped; }
};

#define TYPE_WRAPPER(W, X) \
  struct X##Tag{}; \
  typedef TypeWrapper<W, X##Tag> X

This could be in a generic header file, then you could say:
// define types ...
TYPE_WRAPPER(unsigned, ProcessHandle);
TYPE_WRAPPER(unsigned, ThreadHandle);

// use them
ProcessHandle ph(some_unsigned_var);
unsigned x = ph.getWrapped();
// etc but
ThreadHandle th = ph;