A bizarre C++ wart wants us to declare FromStack overloads

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).

stepmania/src/EnumHelper.h

@@ -127,9 +127,8 @@ const RString &EnumToString( int iVal, int iMax, const char **szNameArray, auto_
 		return (X)(i+1); /*invalid*/	\
 	}
 
-#define LuaDeclareType(X) \
+// currently unused
-namespace LuaHelpers { bool FromStack( lua_State *L, X &Object, int iOffset ); } \
+#define LuaDeclareType(X)
-namespace LuaHelpers { void Push( lua_State *L, const X &Object ); }
 
 #define LuaXType(X)	\
 template struct EnumTraits<X>; \
@@ -162,8 +161,8 @@ static void Lua##X(lua_State* L) \
 REGISTER_WITH_LUA_FUNCTION( Lua##X ); \
 template<> X EnumTraits<X>::Invalid = enum_add2( NUM_##X, 1 ); \
 template<> const char *EnumTraits<X>::szName = #X; \
-bool LuaHelpers::FromStack( lua_State *L, X &Object, int iOffset ) { Object = Enum::Check<X>( L, iOffset ); return true; } \
+namespace LuaHelpers { template<> bool FromStack<X>( lua_State *L, X &Object, int iOffset ) { Object = Enum::Check<X>( L, iOffset ); return true; } } \
-void LuaHelpers::Push( lua_State *L, const X &Object ) { Enum::Push<X>( L, Object ); }
+namespace LuaHelpers { template<> void Push<X>( lua_State *L, const X &Object ) { Enum::Push<X>( L, Object ); } }
 
 #endif
 

stepmania/src/LuaBinding.h

@@ -156,7 +156,7 @@ public:
 	void T::PushSelf( lua_State *L ) { Luna<B>::PushObject( L, Luna<T>::m_sClassName, this ); } \
 	static Luna##T registera##T; \
 	/* Call PushSelf, so we always call the derived Luna<T>::Push. */ \
-	namespace LuaHelpers { template<> void Push( lua_State *L, T *pObject ) { pObject->PushSelf( L ); } }
+	namespace LuaHelpers { template<> void Push<T*>( lua_State *L, T *const &pObject ) { pObject->PushSelf( L ); } }
 
 #define DEFINE_METHOD( method_name, expr ) \
 	static int method_name( T* p, lua_State *L ) { LuaHelpers::Push( L, p->expr ); return 1; }

stepmania/src/LuaManager.cpp

@@ -21,6 +21,19 @@ static LuaFunctionList *g_LuaFunctions = NULL;
 	#pragma warning (disable : 4611)
 #endif
 
+namespace LuaHelpers
+{
+	template<> void Push<bool>( lua_State *L, const bool &Object );
+	template<> void Push<float>( lua_State *L, const float &Object );
+	template<> void Push<int>( lua_State *L, const int &Object );
+	template<> void Push<RString>( lua_State *L, const RString &Object );
+
+	template<> bool FromStack<bool>( Lua *L, bool &Object, int iOffset );
+	template<> bool FromStack<float>( Lua *L, float &Object, int iOffset );
+	template<> bool FromStack<int>( Lua *L, int &Object, int iOffset );
+	template<> bool FromStack<RString>( Lua *L, RString &Object, int iOffset );
+}
+
 struct ChunkReaderString
 {
 	ChunkReaderString( const RString &sBuf ): m_sBuf(sBuf) { m_bDone = false; }
@@ -68,16 +81,17 @@ void LuaManager::UnsetGlobal( const RString &sName )
 	LUA->Release( L );
 }
 
+namespace LuaHelpers
+{
+	template<> void Push<bool>( lua_State *L, const bool &Object ) { lua_pushboolean( L, Object ); }
+	template<> void Push<float>( lua_State *L, const float &Object ) { lua_pushnumber( L, Object ); }
+	template<> void Push<int>( lua_State *L, const int &Object ) { lua_pushinteger( L, Object ); }
+	template<> void Push<RString>( lua_State *L, const RString &Object ) { lua_pushlstring( L, Object.data(), Object.size() ); }
 
-void LuaHelpers::Push( lua_State *L, const bool &Object ) { lua_pushboolean( L, Object ); }
+	template<> bool FromStack<bool>( Lua *L, bool &Object, int iOffset ) { Object = !!lua_toboolean( L, iOffset ); return true; }
-void LuaHelpers::Push( lua_State *L, const float &Object ) { lua_pushnumber( L, Object ); }
+	template<> bool FromStack<float>( Lua *L, float &Object, int iOffset ) { Object = (float)lua_tonumber( L, iOffset ); return true; }
-void LuaHelpers::Push( lua_State *L, const int &Object ) { lua_pushinteger( L, Object ); }
+	template<> bool FromStack<int>( Lua *L, int &Object, int iOffset ) { Object = lua_tointeger( L, iOffset ); return true; }
-void LuaHelpers::Push( lua_State *L, const RString &Object ) { lua_pushlstring( L, Object.data(), Object.size() ); }
+	template<> bool FromStack<RString>( Lua *L, RString &Object, int iOffset )
-
-bool LuaHelpers::FromStack( Lua *L, bool &Object, int iOffset ) { Object = !!lua_toboolean( L, iOffset ); return true; }
-bool LuaHelpers::FromStack( Lua *L, float &Object, int iOffset ) { Object = (float)lua_tonumber( L, iOffset ); return true; }
-bool LuaHelpers::FromStack( Lua *L, int &Object, int iOffset ) { Object = lua_tointeger( L, iOffset ); return true; }
-bool LuaHelpers::FromStack( Lua *L, RString &Object, int iOffset )
 	{
 		size_t iLen;
 		const char *pStr = lua_tolstring( L, iOffset, &iLen );
@@ -88,6 +102,7 @@ bool LuaHelpers::FromStack( Lua *L, RString &Object, int iOffset )
 
 		return pStr != NULL;
 	}
+}
 
 void LuaHelpers::CreateTableFromArrayB( Lua *L, const vector<bool> &aIn )
 {

stepmania/src/LuaManager.h

@@ -81,17 +81,10 @@ namespace LuaHelpers
 	void PushValueFunc( lua_State *L, int iArgs );
 
 	template<class T>
-	void Push( lua_State *L, T *pObject );
+	void Push( lua_State *L, const T &Object );
 
-	void Push( lua_State *L, const bool &Object );
+	template<class T>
-	void Push( lua_State *L, const float &Object );
+	bool FromStack( lua_State *L, T &Object, int iOffset );
-	void Push( lua_State *L, const int &Object );
-	void Push( lua_State *L, const RString &Object );
-
-	bool FromStack( Lua *L, bool &Object, int iOffset );
-	bool FromStack( Lua *L, float &Object, int iOffset );
-	bool FromStack( Lua *L, int &Object, int iOffset );
-	bool FromStack( Lua *L, RString &Object, int iOffset );
 
 	template<class T>
 	bool Pop( lua_State *L, T &val )

stepmania/src/LuaReference.cpp

@@ -163,20 +163,23 @@ RString LuaReference::Serialize() const
 	return sRet;
 }
 
-bool LuaHelpers::FromStack( lua_State *L, LuaReference &Object, int iOffset )
+namespace LuaHelpers
+{
+	template<> bool FromStack<LuaReference>( lua_State *L, LuaReference &Object, int iOffset )
 	{
 		lua_pushvalue( L, iOffset );
 		Object.SetFromStack( L );
 		return true;
 	}
 
-bool LuaHelpers::FromStack( lua_State *L, apActorCommands &Object, int iOffset )
+	template<> bool FromStack<apActorCommands>( lua_State *L, apActorCommands &Object, int iOffset )
 	{
 		LuaReference *pRef = new LuaReference;
 		FromStack( L, *pRef, iOffset );
 		Object = apActorCommands( pRef );
 		return true;
 	}
+}
 
 LuaTable::LuaTable()
 {

stepmania/src/LuaReference.h

@@ -51,12 +51,6 @@ private:
 
 typedef AutoPtrCopyOnWrite<LuaReference> apActorCommands;
 
-namespace LuaHelpers
-{
-	bool FromStack( lua_State *L, LuaReference &Object, int iOffset );
-	bool FromStack( lua_State *L, apActorCommands &Object, int iOffset );
-}
-
 class LuaTable: public LuaReference
 {
 public:

stepmania/src/MessageManager.h

@@ -3,6 +3,7 @@
 #ifndef MessageManager_H
 #define MessageManager_H
 
+#include "LuaManager.h"
 struct lua_State;
 
 enum Message
@@ -201,6 +202,8 @@ public:
 	bool operator != ( const T &other ) const { return val != other; }
 };
 
+namespace LuaHelpers { template<class T> void Push( lua_State *L, const BroadcastOnChange<T> &Object ) { LuaHelpers::Push<T>( L, Object.Get() ); } }
+
 template<class T, int N>
 class BroadcastOnChange1D
 {

stepmania/src/Preference.h

@@ -5,6 +5,7 @@
 
 #include "EnumHelper.h"
 #include "RageUtil.h"
+#include "LuaManager.h"
 class XNode;
 
 struct lua_State;
@@ -115,6 +116,8 @@ private:
 	void (*m_pfnValidate)(T& val);
 };
 
+namespace LuaHelpers { template<typename T, typename U> void Push( lua_State *L, const Preference<T, U> &Object ) { LuaHelpers::Push<T>( L, Object.Get() ); } }
+
 template <class T>
 class Preference1D
 {

stepmania/src/RageTypes.cpp

@@ -36,11 +36,14 @@ void RageColor::FromStack( lua_State *L, int iPos )
 	lua_pop( L, 5 );
 }
 
-bool LuaHelpers::FromStack( lua_State *L, RageColor &Object, int iOffset )
+namespace LuaHelpers
+{
+	template<> bool FromStack<RageColor>( lua_State *L, RageColor &Object, int iOffset )
 	{
 		Object.FromStack( L, iOffset );
 		return true;
 	}
+}
 
 static const char *CullModeNames[] =
 {

stepmania/src/RageTypes.h

@@ -200,11 +200,6 @@ public:
 	float r, g, b, a;
 } SM_ALIGN(16);
 
-namespace LuaHelpers
-{
-	bool FromStack( lua_State *L, RageColor &Object, int iOffset );
-}
-
 /* Convert floating-point 0..1 value to integer 0..255 value. *
  *
  * As a test case,

stepmania/src/ThemeMetric.h

@@ -72,10 +72,9 @@ public:
 	{
 		if( m_sName != ""  &&  THEME  &&   THEME->IsThemeLoaded() )
 		{
-			using namespace LuaHelpers;
 			Lua *L = LUA->Get();
 			THEME->PushMetric( L, m_sGroup, m_sName );
-			if( !FromStack(L, m_currentValue, -1) )
+			if( !LuaHelpers::FromStack(L, m_currentValue, -1) )
 				m_currentValue = T();
 			lua_pop( L, 1 );
 			LUA->Release(L);