Mod multiplayer

[Ranakastrasz]

"Cannot Join. The following mod event handlers are not identical between you and the server. This indicates that the following mods are not multiplayer (save/load) safe."

What causes this error in a mod, and how do I fix it?
viewtopic.php?f=144&t=26473

Its kinda irritating, and I didn't change anything.

[Nexela]

You are registering tick in on_init

Conditionally removing tick in the tick handler

not checking on_load to see if the tick handler is registered or not.

[Nexela]

You are also changing it around to things like 0 and nil

[bobingabout]

Long story short, when it comes to variables, only ever do 1 of 2 things.

Everything in global
A constant (varible = value and NEVER change it)
local within a function for temporary variables (calculated the same by every player)

if it doesn't fit one of those things, you're doing it wrong. A recent update changed to error when it detects these issues, rather than just allowing a possible desync.

[Ranakastrasz]

Hmm.

I suppose need to find a more recent mod to copy, since I've been doing that for a long time, given it is how other mods did that.

[Ranakastrasz]

You are registering tick in on_init

I thought you were supposed to do that?

Conditionally removing tick in the tick handler

Forgot to remove that. IT never runs anyway, since "shouldKeepTicking" cannot change to anything but true. Its an artifact from the mod.. Probably from V11 or something that I copied it from.
Had events to turn the ticker on and off.

not checking on_load to see if the tick handler is registered or not.

I thought you couldn't double-register, and it just overrode it, at least in a single mod. After all, you deregister by setting it to nil, or null, or whichever it is in lua.


The way I understand it now, is that you need to register on game initilization, and on Mod configuration change, which are the two possiblities that can occur. Both run only when the host starts the game.


Could someone point me at how to do this correctly? Its been annoying pretty much since I started modding.

[Nexela]

Registering in on_init is fine but that means you are conditionally registering. If you don't want to register conditionally then move your tick registration out of on_init

Code: Select all

on_init
 global.ticking = true
 register on_tick()
end

on_load
 if global.ticking = true then
 register on_tick()
end

on_tick
if don't need to tick anymore then
global.ticking = false
de register on_tick()
end

if you don't need a conditional tick handler then just

Code: Select all

on_init
--set up all vars
end

script.on_event(defines.events.on_tick, tick)

http://lua-api.factorio.com/latest/Data-Lifecycle.html

[Ranakastrasz]

Ok, that makes sense.

I think I understand.