Introduce TypeTag<T> template whose int value differs for each T.

This replaces type_tag<T>(), which searched and possibly extended the type_tags
unordered_map at runtime. If we called lua_emplace<T>() from different threads,
that would require locking type_tags.

In contrast, the compiler must instantiate a distinct TypeTag<T> for every
distinct T passed to lua_emplace<T>(), so each gets a distinct value at static
initialization time. No locking is required; no lookup; no allocations.

Add a test to llluamanager_test.cpp to verify that each distinct T passed to
lua_emplace<T>() gets its own TypeTag<T>::value, and that each gets its own
destructor -- but that different lua_emplace<T>() calls with the same T share
the same TypeTag<T>::value and the same destructor.

0 files changed, 0 insertions, 0 deletions