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- Subject: Re: How can I have multiple scripts running simultaneously and have scripts pause and wait? (eg. using Lua for a MUD)
- From: Nick Gammon <nick@...>
- Date: Thu, 9 Aug 2007 08:17:30 +1000
On 09/08/2007, at 4:59 AM, John Klimek wrote:
We will have lots scripts running and I'm not sure how to handle a
1) Should I just have one lua_state or one lua_state for each user?
2) Suppose I want to ask the user a question and get a response in
a Lua script?
You are asking about the server end, right?
I have done a considerable amount of work on this very question, as I
started writing a MUD in straight Lua, and am collaborating with
David Haley on doing a MUD server written in C++ with Lua scripting.
I have also added Lua scripting into an existing SMAUG MUD code-base,
see this forum posting for the exact details:
In the MUD written entire in Lua, I used a single Lua state for the
whole MUD, as players needed to communicate with each other.
For the Lua add-on to SMAUG, I initially made a state per player,
because each state was only concerned with things that player was
doing (eg. their own quests). Then I added another per-MUD state to
handle things (like resetting an area) that was not directly related
to any particular player.
This post describes the scripted reset system:
To make scripts pause and wait I would definitely use coroutines,
they are ideal for that purpose. In your example of asking the player
a question, you display the question, and yield the coroutine in such
a way that the server knows that you are awaiting player input. Then
when the player input arrives (or, a timeout occurs), the coroutine
I did an example of doing that at the MUD client end, here:
The above example uses a combination of Lua scripting, and timers and
triggers implemented in C++ code in the client.
An example of using coroutines in the Lua MUD is this:
Send (client, "What would you like to be called? ...")
name = coroutine.yield ()
In this example the player input is returned from the yield, so your
script can just be written using natural loops, as if the player had
control over the entire server.
You are welcome to take this discussion to my forum, which maintains
an active interest in both Lua and MUDs.
- Nick Gammon