jecs/demo/src/ReplicatedStorage/std/ref.luau

local world = require(script.Parent.world)
local handle = require(script.Parent.handle)
local refs = {}

local function fini(e, key)
    return function()
        refs[key] = nil
    end
end

local function ref(key): (handle.Handle, (() -> ())?)
    if not key then
        return handle(world:entity())
    end
    local e = refs[key]
    if not e then
        e = world:entity()
        refs[key] = e
    end
    -- Cannot cache handles because they will get invalidated
    return handle(e), fini(e, key)
end

return ref