【高级技巧】Lua函数包装：烈火剑法结算的耗时外挂

local function settle(actor, item)
    -- 为计时把统计代码塞进业务函数体
    local t0 = os.clock()
    doCharge(actor, item)
    logCost(os.clock() - t0)         -- 业务与观测搅在一起
end

-- 包装烈火剑法结算函数，原体零改动
local function timed(fn)
    return function(actor, item)
        local t0 = os.clock()
        local r = {fn(actor, item)}  -- 收全多返回值
        sendmsg(actor, 1, "结算耗时 "
            .. string.format("%.3f", os.clock() - t0) .. " 秒")
        return unpack(r)             -- 原样透传
    end
end
settle = timed(settle)