Implementing stateless game NPC chat scripting using DLR

How would one implement stateless game NPC chat using the DLR - i.e IronPython?

Stateless means something like this:

npc.AddText("Are you dead?")
playerIsDead = npc.GetYesNo()
if playerIsDead:
    npc.AddText("You can't be dead!")
    npc.SendOk()
else:
    npc.AddText("Okay.")
    npc.SendOk()
npc.End()

Instead of:

def Talk(state, action, input):
    if action == -1:
        npc.End()
    elif state == 0:
 开发者_JS百科       npc.AddText("Are you dead?")
        npc.GetYesNo()
    elif state == 1:
        if input:
            npc.AddText("You can't be dead!")
            npc.SendOk()
        else:
            npc.AddText("Okay.")
            npc.SendOk()
        npc.End()

See the difference?

I've thought of one solution: Use one thread per NPC conversation, and AutoResetEvents or something like that. Not feasible because in a real life situation, there can be many NPC conversations (hundreds, if not thousands) going on simuntaneously. Do not want a few thousand threads.

Another way is to have the GetYesNo() and other methods not return anything, and instead simply send the dialog packet to the client, and somehow pause/block/suspend the script. Then, when input is received, it is put in a constantly named variable "input" or so in the ScriptScope.

The only problem is, in this case, how does one block the script, without having a dedicated thread per script?

I know it is doable in C++ with Lua, by having e.g GetYesNo simply send the script, and call lua_yield. When input is received, one of the lua_push (e.g. lua_pushinteger) methods are called, followed by a call to lua_resume.

Also, does anyone have any better solutions?

Thanks.

If IronPython has support fpr PEP342 (coroutines via enhanced generators) you could use those for your scenario: http://docs.python.org/whatsnew/2.5.html#pep-342 (e.g. yield on npc.GetYesNo() and send the value back into the generator and continue from there).