Lua属性换算：按名映射的取值函数

-- 错误：展示层直接读原始字段名，改名即崩
out.atk = item.DC
out.hp = item.HP

local MAP = {
    DC = {key = "minAtk"},
    HP = {key = "maxHp"},
}
local function convert(item, out)
    for src, rule in pairs(MAP) do
        if item[src] then
            out[rule.key] = (out[rule.key] or 0)
                + item[src]
        end
    end
    return out
end