Re: individual globals for coroutines.

["Marcus Brown" <mrbrown@...>]

* David Morris-Oliveros <david@teambondi.com> on Mon, Oct 10, 2005:

> Hi,
> 
> I'm on my next stage of integrating lua into our engine, and have come 
> to a point where it would be wise to ask for advice.
> 
> I want each coroutine to have their own individual global table. I know 
> that you can do this by creating a new table, filling it with whatever 
> you want, and doing a lua_setfenv().
> 
> Now, when I bind my code into lua, i create all sorts of tables and 
> cfunctions in the global table. I still want these new coroutines to be 
> able access my bound tables and cfunctions.
> 

I'm doing the same exact thing in our project - creating a seperate global
namespace for threads with access to the real global table.

Just create your thread's global table, and give it a metatable with the
__index metamethod pointing to the global table:

    namespace = setmetatable({}, {__index = _G})

In C this would look something like:

    lua_newtable(L);
    int metatable = lua_gettop(L);

    lua_pushvalue(L, LUA_GLOBALSINDEX);
    lua_setfield(L, metatable, "__index");    /* {__index = _G} */

Then set this as the metatable of your namespace.

I believe this was mentioned in PIL, section 14.3.