Re: Optimizing variable access from C

[David Jones <drj@...>]

In message <BCF3A47F02AB8643BB391B0517EBD6440394ECE6@red-msg-08.redmond.corp.mi
crosoft.com>, "Curt Carpenter" writes:
> > How about doing it other way around? I.e. storing the variables in C
> and accessing them with set/get functions from Lua?
> 
> Then I have to have some sort of reverse string lookup table
> (duplicating what Lua already does), which seems about as expensive (and
> more complex).

Store your variable in C.  EG

float coolParm1;

For each different C type you use you'll need a new tag.

Create a lua userdata object with the appropriate tag that points to the C
variable:

lua_pushusertag(L, &coolParm1, myFloatTag);

Bind this value to a lua global variable:

lua_setglobal(L, "coolParm1");

Define a getglobal and setglobal tag method for myFloatTag that
translates the representation in C into a representation in lua.  In the
case of float this is obvious.

Now you can access the C variable from lua transparently.

I'm sure that's what the original respondent had in mind.

Cheers,
 drj