Re: Global variables, local functions?

[David Morris-Oliveros <david.morrisoliveros@...>]

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