Basically I want to make a type that is just a fixed size array with the same type.
Like in C i would do int[4] to make a array of 4 ints. Is there any way to do this with the luau type system?
I already tried something like
type Sizes = {number,number,number,number}
but that doesnt’ work.
To my knowledge Roblox’s implementation of Luau doesn’t support the ability to create fixed-length arrays.
I dont actually want a fixed size array but just a way to make the typechecker only allow a certain array size
I’d say for you to index the length of the array with “false” statements. Then everytime you want to Index something inside it, you can check if the value at that index equals to false, meaning that the slot is available, if it returns nil then it means it’s out of the range
You can use table.create:
local t = table.create(4, 0)
print(t) --{0, 0, 0, 0}
Here’s a function to verify if a table only has 4 elements that are all number values:
local function verifyArray(t: {}): boolean
if #t ~= 4 then return false end
for _, v in pairs(t) do
if type(v) ~= "number" then return false end
end
return true
end
And to typecheck you can use the {number} typecheck that means “An array of numbers” although it wont typecheck if the array has exactly 4 elements in it.
yea i guess its not possible to do it with the typechecker then thanks for tryin tho
I never said it’s not possible, I just don’t know how to do it.
Did you make sure your scripts are in strict mode?
the best you can get is
type Sizes = {[number] : number}
as to perform a size check would require runtime operations which is against the philosophy of luau, as its not a statically typed language. if you want to specify size otherwise, try using strings:
type Sizes = {
["1"] : number,
["2"] : number,
["3"] : number,
["4"] : number
}
and then doing tostring(number) when indexing your table. shrug.
Apologies for bumping, but I think this would be a nice solution for numerically based arrays.
You could take a look at the buffer type!
-- let's say this is an unsigned 8 bit integer buffer
local index = 0
local array = buffer.create(4)
buffer.writeu8(array, 1, index) -- basically array[index] = 1
buffer.readu8(array, index) -- basically array[index]
This will error if you try and write outside the size.
I’m oversimplifying it with the comparisons, but you should get the idea.