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- Subject: Re: Q: Lua 5.2 thread environments...
- From: Patrick Donnelly <batrick@...>
- Date: Wed, 30 Mar 2011 14:49:16 -0400
On Wed, Mar 30, 2011 at 2:11 PM, Anthony Howe <firstname.lastname@example.org> wrote:
> >From the 5.2 alpha documentation, section 8.1 – Changes in the Language:
> "Threads do not have individual environments. All threads share a single fixed environment.
> This doesn't sound good.
It is good. Threads don't have "environments"; functions do. What the
quote above really means is Lua no longer has a per-thread context.
(Of course, this per-thread context only applied to C closures using
LUA_GLOBALSINDEX...) It doesn't really make sense and can be easily
emulated through function environments and closures.
> In my current network application I am developing, I rely on the ability for threads to have separate "environments" (contexts) in
> order to ensure that data placed into the thread's global space does NOT appear in another thread's global space or the master state
> from which the thread was originally created.
You can still do this. Thread specific data can be kept in a weak
table within the registry. Alternatively you can maintain state
through closures and upvalues.
> How will a thread ensure that data defined within it remains confined to that thread? Currently I rely on changing the thread's
> LUA_GLOBALSINDEX to a metatable assigned to the thread that confines data.
There is no LUA_GLOBALSINDEX in 5.2.
Again, use a weak table in the registry for thread specific data.
- Patrick Donnelly