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Lua states confusion

2 posts in this topic

Hello there.

After digging deeply in previous subjects of that kind I came up to great confusion regarding lua states.
There is certain scheme of my scripting vision, which I derived from lpmuds and which I want to translate to Lua, more or less.
I managed to achieve similar result while using lua_state per entity basis, but what I've found out is a great amount of memory being absorbed when reaching high entity count. That have should be clear to me if I put my built-in functions to every state, forcing it to grow with huge impact!
After few tests I came up to the point that I need one state for all the entities, but a whole bunch of problems appeared due to the shape of my scripting vision:P

Maybe someone could help me solving this issue. Here's some overview to what I achieved with multiple states.
Some pseudo code of LionClassLib and lion.lua

function LionClassLib:CreateLion()
setting default values

function LionClassLib:LionCallback()

-- This function is called from c api -> every time a new entity is created
function create_object()
-- this() -> returns current object table (defined through binding objects to uids in inherit.lua, apply only when
trying to fight with one lua state, in case of many states this() will lead to base object, so this part works anyway)

function do_anything()

-----> lion.lua <-----
require "inherit"
require "LionClassLib"

LocalObject = inheritFrom(LionClassLib); -> sets metatables and returns table/object with class def and standard behavior

function LocalObject:CreateLion()
LionClassLib:CreateLion(); -- Setting the parent's constructor
-- additional local stuff if needed


While being on many states the great advantage was that I could call another object creation through C API and it didn't
destroy globals of the current one. Now I can't, but this part I can omit.
The idea behind many states was that I could lual_dofile every script, pass initial callbacks and it ran ok. Then I was able to call events from api the same way.
But at this point I'll have the following problem:

1. Clone Entity 1 with lion.lua
2. Load script and call create_object (this():CreateLion)
3. Clone Entity 2 with monkey.lua
4. Load script and call create_object (this():CreateMonkey)
5. It's obvious it will be ok until next point:P
6. Clone Entity 3 with dofile lion.lua! CRASH: luadofile won't compile the same file, the last global create_object comes from monkey.lua where there is no function CreateLion.

So, I hope the idea is quite clear. I was trying to play with environments with setfenv/getfenv etc but I'm not sure it's the right way. I can try with lua_state per script, then it might work, but I'm not quite sure if something wouldn't suddenly blow up.

If someone could direct me in proper direction I'd be pleased.

Thanks for reading.

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You should only call luaL_dofile once for each file. It looks like you're using the same function names in each file and then overwriting them each time you load a new lua file. I'd suggest putting them into tables, so in lion.lua you'd create a table called lion, and put all the functions into that table. Same with all the others. This avoids name clashes. You'd just have to switch to the appropriate table before making your function calls.

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Thanks a lot! After implementation and some little fixes it works great. The only thing I left (and it seems working) is dofile every time a script is initialized. This is due to the fact there is an object creation at inheritFrom call. It registers every new object behind the scene so everything is set up properly when managing further calls from api, and even I managed to init scripts from within running scripts with unlimited level of depth:P How it will bounce off the performance, don't know, but thanks for a good advice.

Problem solved. Might be closed.

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