Scripting with Lua - Game Coding Complete - page 360

To assign a value to a value to a LuaObject , use the Assign*() functions:

n void AssignNil(LuaState* state)

n void AssignBoolean(LuaState* state, bool value)

n void AssignInteger(LuaState* state, int value)

n void AssignNumber(LuaState* state, double value)

n void AssignString(LuaState* state, const char* value)

n void AssignWString(LuaState* state, const wchar_t* value)

n void AssignUserData(LuaState* state, void* value)

n void AssignLightUserData(LuaState* state, void* value)

n void AssignObject(LuaState* state, LuaObject& value)

n void AssignNewTable(LuaState* state, int narray = 0, int nhash = 0)

Notice that the various assignment functions require a LuaState pointer. This is
because every valid value must be attached to a state in Lua, so when you create a
new value, you tell LuaPlus where to attach it.

Tables
LuaObject has a number of functions and operators specifically written to help deal
with tables. The easiest way to look up a value on a table is to use the overloaded
array access operator. You can also use the GetByName() , GetByObject() ,or
GetByIndex() functions to retrieve a value from the table. For example, let ' s say

we have the following table in Lua:

positionVec ={x=10,y=15}
Let s also say that this value is stored in a LuaObject called positionTable .We

can access fields on this table like so:

'

GCC_ASSERT(positionTable.IsTable()); // safety first

LuaObject x = positionTable[ “ x ” ]; // this is one way

LuaObject y = positionTable.GetByName( “ y ” ); // here ' s another

// let s fill up a Vec2:

GCC_ASSERT(x.IsNumber() && y.IsNumber()); // more type checking
Vec2 vec(x.GetFloat(), y.GetFloat());

'

That s all there is to it. Of course, without any type safety, you need to handle all the

error checking yourself.

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