Lua驼峰转换：下划线串的命名风格互转

local function toCamel(s)
    return string.gsub(s, "_%a", string.upper)   -- 整个匹配被大写
end
sendmsg(actor, 1, toCamel("max_hp"))   -- 输出 MAX_HP，全错

local function toCamel(s)
    return (string.gsub(s, "_%a", function(m)
        return string.upper(string.sub(m, 2, 2))
    end))
end
local function toSnake(s)
    return (string.gsub(s, "%u", function(m)
        return "_" .. string.lower(m)
    end))
end
sendmsg(actor, 1, toCamel("max_hp") .. " / "
    .. toSnake("maxHp"))