【高级技巧】Lua记忆化缓存：仓库属性合计只算一次的闭包

local function totalValue(list)
    local sum = 0
    for i = 1, #list do sum = sum + list[i].price end
    return sum                          -- 每次全量重算
end

local function memoTotal()
    local cache = {}
    return function(actor, key, list)
        local hit = cache[key]
        if hit and os.time() - hit.t < 30 then
            return hit.v                -- 30秒内直接回缓存
        end
        local sum = 0
        for i = 1, #list do sum = sum + list[i].price end
        cache[key] = {v = sum, t = os.time()}
        sendmsg(actor, 1, "裁决之杖合计 " .. sum .. " 已缓存")
        return sum
    end
end