CODEWITHSUNDEEP
lua
askiere
askiere

Reputation: 3

The Binding of Isaac Mod Returns "attempt to perform arithmetic on nil value"

I am trying to make my first mod for The Binding Of Isaac, but it says that the speed value is a nil value. As someone who doesn't know a lot about programming, why is it set to nil instead of the in-game value of 1? And how can I fix it?

local sodamod = RegisterMod("soda mod", 1)
local soda = Isaac.GetItemIdByName("Soda Bottle")
local speedgive = 0.5

function sodamod:EvaluateCache(player, cacheflags)
    if cacheflags & CacheFlag.CACHE_SPEED == CacheFlag.CACHE_SPEED then
        local itemcount = player:GetCollectibleNum(soda)
        local addspeed = speedgive * itemcount
        player.Speed = player.Speed + addspeed
    end
end

sodamod:AddCallback(ModCallbacks.MC_EVALUATE_CACHE, sodamod.EvaluateCache)

I tried setting the speed value as a variable, but it still returned as an error.

Upvotes: 0

Views: 282

Answers (1)

Oka
Oka

Reputation: 26355

Per this documentation, the EntityPlayer movement speed stat is MoveSpeed.

Try something like:

local sodamod = RegisterMod("soda mod", 1)
local soda = Isaac.GetItemIdByName("Soda Bottle")

local increase = 0.5

function sodamod:EvaluateCache(player, cacheflags)
    if cacheflags & CacheFlag.CACHE_SPEED == CacheFlag.CACHE_SPEED then
        local count = player:GetCollectibleNum(soda)

        player.MoveSpeed = player.MoveSpeed + (count * increase)
    end
end

sodamod:AddCallback(ModCallbacks.MC_EVALUATE_CACHE, sodamod.EvaluateCache)

Aside, from MC_EVALUATE_CACHE:

Note that the value passed to the callback will always be an exact value of the CacheFlag enum. It is never a composition of two or more CacheFlags. Thus, you should always use normal equality instead of bitwise operators when comparing the cache flag.

AFAICT,

function sodamod:EvaluateCache(player, flag)
    if flag == CacheFlag.CACHE_SPEED then
        --- ...

is more appropriate.

Upvotes: 0

Related Questions