Re: Newbie: Cooperative Multitasking

[Jeroen Janssen <japj@...>]

Derek Wong wrote:
> 
> Hi everybody,
> 
> I'm new to the list and new to lua. I was wondering if someone might
> offer me some advice at implementing cooperative multitasking with
> lua scripts. I'm an amateur programmer so please excuse me if I've
> used the wrong terminology.

Well (it's some time ago that I've been using lua, but) here are some ideas regarding cooperative multitasking (these
ideas are relative simple to implement I did it some time ago as an experiment when I was trying to find a way to get
lua working with my demosystem where there's a list of (graphical) tasks that should be executed cooperatively...
anyway.. I remember Bret to implement multitasking by rewriting some things in lua (don't know if it's *that* simple
anyway, but that's something Bret might care to comment about) resulting in lua having some cooperative multitasking
facility 'embedded'. 

You could creete a C++ base 'task' class with a virtual 'run' function. export this class to lua (with tolua). create a
new lua class derived from 'task', create a new C++ class derived from 'task' and export this class to lua.

Next create a lua function addtask that can add a specified task to a lua list. Last create a runtasks function in lua
that can iterate through the list and call appropriate run functions

task1=CPP_Task::new()
task2=LUA_Task::new()

addtask(task1);
addtask(task2);

runtasks();

because you exported the C++ class to lua and because you iterate the list from within lua this will allow both the C++
run functions as well ass the lua run functions to be executed in a cooperative multitasking way. Just make sure that
whatever you want to do from C++ is added to the list.

This idea can be 'enhanced' by adding a flag variable to the base class that has information about wether or not to
execute the run function (thus allowing some form of 'pause' functionality).

I hope this makes some sence, if not ..... then please let me know :)  it's been some time that I've been working with
lua, but I think that the mailinglist might contain some more information about what I've been trying do explain here.

-- 
        Best regards,
                
                Jeroen Janssen

+++
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citadel. This is essentially the basis of all military thinking.
        -- (Terry Pratchett, Eric)
+++