【高级技巧】惰性求值：大表按需构建的元表代理

local function lazyTable(compute)
    local entity = {}
    return setmetatable(entity, {
        __index = function(t, k)
            local v = compute(k)
            if v == nil then
                return nil
            end
            rawset(t, k, v)
            return v
        end,
    })
end
local WORDS = {
    atk = { name = "攻击强化", base = 25 },
    hp = { name = "生命强化", base = 80 },
}
local entryTable = lazyTable(function(k)
    local w = WORDS[k]
    if w == nil then
        return nil
    end
    return { label = w.name, value = w.base * 12 }
end)

local function showEntry(actor, key)
    actor = getplayerbyname(actor)
    local e = entryTable[key]
    if e == nil then
        sendmsg(actor, 1, "未收录词条：" .. key)
        return
    end
    sendmsg(actor, 1, e.label .. " 词条值：" .. e.value)
end