Re: Best way to pause (sleep?) inside of lua script

[Thomas Wrensch <twrensch@...>]

I suggest using coroutines.

Each user script is a function that is wrapped in a coroutine. Functions
like sleep call yield. The scripts can be managed by a simple scheduler 
written in Lua (There's one on the Wiki somewhere, and I can send you one 
if that one doesn't work).

The problem with this technique is that coroutines can't yield if there is 
a C-call between them. This is not to say you can't call into C/C++ code 
from a coroutine, just that you cannot have situations such as having a 
Lua coroutine call C-code, which in turn executes some Lua code, which in 
turn does a yield. This problem has been discussed extensively on the 
list in the past.

The advantage is natural scripts that doesn't need to register action 
handlers, and the ability to share a single Lua state for all scripts.

I'm not sure if this approach will work for you. Depends on the 
architecture of your MUD.

 - Tom

On Thu, 8 Dec 2005, John Klimek wrote:

> Date: Thu, 8 Dec 2005 16:09:12 -0500
> From: John Klimek <jklimek@gmail.com>
> Reply-To: Lua list <lua@bazar2.conectiva.com.br>
> To: Lua list <lua@bazar2.conectiva.com.br>
> Subject: Best way to pause (sleep?) inside of lua script
>
> I'm developing a MUD (multi-user dungeon game) as a side project and
> I'm going to use Lua for scripting.  You've probably seen my last
> e-mail regarding how to share objects but I have that mostly figured
> out.  However, I have another question...
>
> Let's say I want to have a script do something like this:   (pseudo-code)
>
> npc = CreateNPC("Bob");
> npc:SetRoom("main");
> npc:Say("Hello everybody in the room!");
>
> SLEEP(1000);  -- Sleep for one second
> npc:Say("Hello again!!");
>
> SLEEP(1000);  -- Sleep for another second
> npc:Say("I'm being really annoying now!!");
>
>
> Now I'm not even sure if SLEEP() is the correct command, but as far as
> my host application is concerned if I pause in a Lua script it will
> halt the entire program until lua_dofile() returns.
>
> What's the best way to implement the Lua scripting engine into a game?
>
> How can I get Lua to pause (eg. sleep) without stopping my entire game?
>
> Can one Lua instance be shared between shared threads?  (eg. several
> players in the game will be executing Lua scripts)
>
> Should I spawn a seperate thread for every single lua script being run?
>
>
> Any advice would be greatly appriciated!!

twrensch@sdf.lonestar.org
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