add ActorUtil::SetParamFromStack, ActorUtil::GetParam. Save params to

a table, not as global variables.  Saving and loading from globals is still
around temporarily.

stepmania/src/Actor.cpp

@@ -196,14 +196,7 @@ void Actor::LoadFromNode( const CString& sDir, const XNode* pNode )
 	{
         if( pChild->m_sName == "Input" )
         {
-			/*
-			 * Parameters are set as globals by ActorUtil::LoadFromNode and
-			 * Screen::InitScreen.
-			 * If parameters are specified here, save them to the actor.  Accessing
-			 * parameters as globals directly is deprecated.  (However, it's still
-			 * the only way to access them when self isn't available, such as from
-			 * RunAtExpressionS.)
-			 */
+			/* If parameters are specified here, save their values to the actor. */
 			CString sName;
 			if( !pChild->GetAttrValue( "Name", sName ) )
 				RageException::Throw( ssprintf("Input node in '%s' is missing the attribute 'Name'", sDir.c_str()) );
@@ -214,7 +207,7 @@ void Actor::LoadFromNode( const CString& sDir, const XNode* pNode )
             Lua *L = LUA->Get();
             this->PushSelf( L );
             LuaHelpers::Push( sName, L );
-			lua_getglobal( L, sName );
+			ActorUtil::GetParam( L, sName );
 
 			if( lua_isnil(L, -1) && !bOptional )
 				RageException::Throw( "Actor in \"%s\" requires parameter \"%s\" that is not set", sDir.c_str(), sName.c_str() );

stepmania/src/ActorUtil.cpp

@@ -104,6 +104,70 @@ retry:
 	sPath = DerefRedir( sPath );
 }
 
+static void PushParamsTable( Lua *L )
+{
+	lua_pushstring( L, "Params" );
+	lua_rawget( L, LUA_GLOBALSINDEX );
+	if( lua_isnil(L, -1) )
+	{
+		lua_pop( L, 1 );
+		lua_newtable( L );
+		lua_pushstring( L, "Params" );
+		lua_pushvalue( L, -2 );
+		lua_rawset( L, LUA_GLOBALSINDEX );
+	}
+}
+
+/* Set an input parameter to the first value on the stack.  If pOld is non-NULL,
+ * set it to the old value.  The value used on the stack will be removed. */
+void ActorUtil::SetParamFromStack( Lua *L, CString sName, LuaReference *pOld )
+{
+	int iValue = lua_gettop(L);
+
+	PushParamsTable( L );
+	int iParams = lua_gettop(L);
+
+	LuaHelpers::Push( sName, L );
+	int iName = lua_gettop(L);
+
+	/* Save the old value. */
+	if( pOld != NULL )
+	{
+		lua_pushvalue( L, iName );
+		lua_rawget( L, iParams );
+		pOld->SetFromStack( L );
+	}
+
+	/* Backwards-compatibility: set the value as a global.  This is strongly
+	 * deprecated. */
+	lua_pushvalue( L, iName );
+	lua_pushvalue( L, iValue );
+	lua_rawset( L, LUA_GLOBALSINDEX );
+
+	/* Set the value in the table. */
+	lua_pushvalue( L, iName );
+	lua_pushvalue( L, iValue );
+	lua_rawset( L, iParams );
+
+	lua_settop( L, iValue-1 );
+}
+
+/* Look up a param set with SetParamFromStack, and push it on the stack. */
+void ActorUtil::GetParam( Lua *L, const CString &sName )
+{
+	/* Search the params table. */
+	PushParamsTable( L );
+	LuaHelpers::Push( sName, L );
+	lua_rawget( L, -2 );
+	lua_remove( L, -2 );
+
+	if( lua_isnil(L, -1) )
+	{
+		/* Deprecated: search globals. */
+		lua_pop( L, 1 );
+		lua_getglobal( L, sName );
+	}
+}
 
 Actor* ActorUtil::LoadFromNode( const CString& sDir, const XNode* pNode )
 {
@@ -136,8 +200,15 @@ Actor* ActorUtil::LoadFromNode( const CString& sDir, const XNode* pNode )
 				CString s;
 				if( pChild->GetAttrValue( "Value", s ) )
 				{
+					/* XXX: don't RunAtExpressionS here; probably don't replace ::, either
+					 * (use regular Lua escapes). */
 					THEME->EvaluateString( s );
-					LUA->SetGlobalFromExpression( sName, s );
+
+					Lua *L = LUA->Get();
+					LuaHelpers::RunScript( L, "return " + s, "", 1 );
+
+					SetParamFromStack( L, sName, NULL );
+					LUA->Release(L);
 				}
 				else
 				{

stepmania/src/ActorUtil.h

@@ -74,6 +74,9 @@ namespace ActorUtil
 	void SortByZPosition( vector<Actor*> &vActors );
 
 	FileType GetFileType( const CString &sPath );
+
+	void SetParamFromStack( Lua *L, CString sName, LuaReference *pOld=NULL );
+	void GetParam( Lua *L, const CString &sName );
 };
 
 #define SET_XY( actor )			ActorUtil::SetXY( actor, m_sName )

stepmania/src/Screen.cpp

@@ -19,16 +19,12 @@
 
 void Screen::InitScreen( Screen *pScreen )
 {
-	/* Set the name of the loading screen, so Actor::LoadFromNode can
-	 * access it. */
+	/* Set the name of the loading screen. */
 	LuaReference Old;
 	{
 		Lua *L = LUA->Get();
-		lua_getglobal( L, "LoadingScreen" );
-		Old.SetFromStack( L );
-
 		LuaHelpers::Push( pScreen->GetName(), L );
-		lua_setglobal( L, "LoadingScreen" );
+		ActorUtil::SetParamFromStack( L, "LoadingScreen", &Old );
 		LUA->Release( L );
 	}
 
@@ -38,7 +34,7 @@ void Screen::InitScreen( Screen *pScreen )
 	{
 		Lua *L = LUA->Get();
 		Old.PushSelf( L );
-		lua_setglobal( L, "LoadingScreen" );
+		ActorUtil::SetParamFromStack( L, "LoadingScreen" );
 		LUA->Release( L );
 	}
 }