Scripting with Lua - Game Coding Complete - page 361

You can also set a field on a table with the various Set*() functions:

n void SetNil(const char* key)

n void SetBoolean(const char* key, bool value)

n void SetInteger(const char* key, int value)

n void SetNumber(const char* key, double value)

n void SetString(const char* key, const char* value)

n void SetWString(const char* key, const wchar_t* value)

n void SetUserData(const char* key, void* value)

n void SetLightUserData(const char* key, void* value)

n void SetObject(const char* key, LuaObject& value)

To add a z field to the table above, you would do the following:

positionTable.SetNumber( , 0);

Iterating through tables is possible with the use of LuaPlus

“ z ”

' s LuaTableIterator .

It ' s somewhat similar in form to STL iterators, but it is not STL compliant. Here ' s

an example that loops through an entire table:

// set up a test table in Lua and read it into a LuaObject
pLuaState->DoString(

“ birthdayList = { John = ' Superman ' , Mary = ' Batman ' } ” );

LuaObject table = pLuaState->GetGlobals().GetByName( “ globalPosition ” );

// loop through the table, printing out the pair
for (LuaTableIterator it(table); it; it.Next())
{

LuaObject key = it.GetKey();
LuaObject value = it.GetValue();
// do whatever you want with the objects …

}
As you can see, looping through a table is relatively straightforward. This is a huge
improvement from the Lua C API with the various lua_next() and lua_pop() calls.

Globals
The previous example had a glaring hole in it. I showed you a table in Lua and how
to get values from the C++ representation, but I didn t show you how to actually read

a Lua variable in C++. In order to do that, I need to pull the curtain back a bit and
show you how global variables are actually stored in Lua.

'