【Lua实战】错误码的设计：数值与消息的双层

---错误码的定义：分段编码
local E = {
    OK          = 0,
    -- 1xxx 通用
    E_UNKNOWN   = 1000,
    E_TIMEOUT   = 1001,
    -- 2xxx 物品
    E_BAG_FULL  = 2001,
    E_NO_ITEM   = 2002,
    -- 3xxx 交易
    E_TRADE_LOCK= 3001,
    E_NO_GOLD   = 3002,
}

---错误的结果构造：码与消息双层
local function fail(code, msg)
    return { ok = false, code = code, msg = msg }
end
local function ok(data)
    return { ok = true, data = data }
end

---业务的使用
function Trade.buy(actor, goodsId)
    if not checkitemw(actor, "金币", 10000) then
        return fail(E.E_NO_GOLD, "金币不足，还差 " ..
            (10000 - (getplayvar(actor, 2, "Gold") or 0)))
    end
    return ok({ goodsId = goodsId })
end

---错误码的登记与提示的同源
local MSG_OF = {
    [E.E_BAG_FULL] = "背包已满，请清理后重试",
    [E.E_NO_GOLD]  = "金币不足",
    [E.E_NO_ITEM]  = "材料不足",
}

function Trade.notify(actor, result)
    if result.ok then return end
    -- 同源的默认提示，业务的定制消息优先
    local msg = result.msg or MSG_OF[result.code] or "操作失败"
    sendmsg(actor, 1, msg)
end

---错误码的监控埋点
function Trade.track(code)
    ErrCode.count[code] = (ErrCode.count[code] or 0) + 1
    if ErrCode.count[code] > 500 then
        Ops.alert("高频错误码: " .. code)
    end
end