Re: Global variables, local functions?

["Raymond Jacobs" <raymondj@...>]

David,

That sounds like a plan, could you 'or anyone else' elaborate on how I
would do the following 'im still pretty new to lua'.

so how can i create a new table, and add _G to it, which points to the
'true' global environment, and then how do I set this new table as the
co-routines environment.

some sample code, or a list of the functions I need to investigate
would be really helpful.

Thanks again =)

-Raymond

On 7/10/06, David Morris-Oliveros <david.morrisoliveros@teambondi.com> wrote:
> First of all, sorry about the chaotic email, it's still too early in the
> morning for me :)
>
> You can try sandboxing the coroutine. That's what we do in our game.
> Each coroutine gets it's own environment, but still with access to the
> global env.
>
> You create a table, whose metatable is the global global, and set that
> to be the local global's table, with an explicit entry to _G. That way,
> you can create local and global stuff:
>
> local really_local_variable = 1
> local_variable = 1
> _G.global_variable = 1
> function local_function () end
> function _G.global_function () end
>
> Also, if you set the local global's metatable to be the global global,
> you get everything else for free. That is, you can access all the
> functions and variables defined in the global global as if they where local:
>
> _G.fibonacci(5)
> fibonacci()
>
> would be the same call (as long as you haven't created a new fibonacci()
> function in you local global).
>
>  From C, you can obtain the local global and then call the function by
> name within that local global.
>
> We keep a table with all of these things:
>
> _G._THREADS = {}
>
> I then add each local global to that table using the C's substate
> pointer's numerical value as key. That way it's easy to extract the
> local global from C, and then call whatever.
>
> This way, you can easily set global variables ( _G.var = value ), or
> local ones (but still have access to them from outside), and all will be
> cleaned up on coroutine exit, because "local" functions exist only
> within the local global table.
>
> Raymond Jacobs wrote:
> > Hey all,
> >
> > In our game we utilize a single Lua_State, and create a co routine
> > (initialized with the main lua_state) for each other script we run.
> >
> > It is great that the variables we create in these other scripts remain
> > global and accessible from any other script we run, however, we run
> > into this problem:
> >
> >
> > if we load 'scriptA.lua' which contains the function onClick()
> >
> > and later load 'scriptB.lua' which doesn't contain an onClick()
> > function, the previous onClick function still remains.
> >
> > so in short, when we run a script (through a co-routine) we would like
> > to start a clean slate as far as functions are concerned, but we still
> > want to be able to access all of the global variables we've created.
> >
> > now, i noticed it is seemingly valid to create functions with the
> > 'local' prefix on them, to me this sounds like what we need (so that
> > the functions don't get embedded into the global area) however I can't
> > figure out how to call a local function from C (all of our co-routine
> > creation, script loading, and function calling happens from C).
> >
> > I am pretty sure someone has run into this issue before, any help
> > would be appreciated.
> >
> > Thanks for your time,
> > Raymond Jacobs
> > Owner,
> > Ethereal Darkness Interactive
> >
>
> --
>
> // david morris-oliveros
> // camera & lua coder
> // david@teambondi.com