Re: Lua 5.1 threads, environments, and 5.2

[GrayFace <sergroj@...>]

On 09.04.2011 14:37, Anthony Howe wrote:
> Q: Essentially how to force Lua application&  library functions to
> inherit the environment of the thread or caller (not the environment of
> where it was defined).
> Ideally I need this to work in 5.1 and 5.2.

Here are my thoughts:

1) For threads in 5.2:

Change coroutine.resume (and coroutine.wrap) to fetch a table 
corresponding to the thread and set it as registry[LUA_RIDX_GLOBALS].

2) In support functions you can refer to registry[LUA_RIDX_GLOBALS] when 
you need to manipulate a global variable.

3) For user code there's no way to do the "fork" without actually 
cloning closures. Take this code for example:
local was_called
function event_handler()
  if not was_called then
    -- do something
    was_called = true
  end
end

No matter what you do, it would do something only for the first thread 
that invoked it.
Thus, I'd suggest having an explicit global variable with thread 
specific data.

--
Best regards,
Sergey Rozhenko                 mailto:sergroj@mail.ru