before the ThemeMetric templates that use them. That's broken
and unreasonable, so change this around a bit and make FromStack
(and Push) templates.
Push() takes a bit of a trick. Some Push overloads push the
actual value: scalars (int, float), RageColor (pushes a table).
Others--most of them--push a reference to a C++ object. We
want the scalars to have a reference parameter type, so we
don't make extra copies of things like RageColor when we push
them. We need to pass C++ objects by pointer (we need to
push the actual object's pointer, not a pointer to a copy).
Further, pushing a scalar is a const operation, but pushing
a reference to an object is not.
To do both with the same template, we handle objects with
this slightly odd template:
template<> void LuaHelpers::Push<T*>( lua_State *L, T *const &pObject );
The actual overload (T) is eg. "Actor*"; this fits within the
general prototype, "Push(lua_State *L, const T &object)", giving
us a const reference to a (non-const) pointer to Actor, and we're
conceptually pushing the pointer.
The net effect of this is that 1: what was before compile errors
now becomes link time errors, but 2: these specializations
don't have to be in the headers (except for new ones for
Preference and BroadcastOnChange).
This is PushTable and not PushSelf, to distinguish this from
the PushSelf used in other classes. Classes that can PushSelf
actually push a reference to itself to Lua, but that's only
valid for objects with a lifetime; many RageColors are temporaries.
Glenn Maynard