erlang 关于解决多层代码嵌套问题
1.使用throw?抛出异常，结束判断，立即返回
check(Player,?Goods,?Count)?->
??try
????Info??=?Player#player.info,
????Time??=?misc:seconds(),
????case?map_api:check_goods(Info#info.map_id,?Goods#goods.goods_id)?of
???????true?->
?????????ok????=?check_count(Goods#goods.count,?Count),
?????????ok???=?check_pro(Info#info.pro,?Goods#goods.pro),
?????????ok???=?check_sex(Info#info.sex,?Goods#goods.sex),
?????????ok???=?check_lv(Info#info.lv,?Goods#goods.lv),
?????????ok????=?check_time(Time,?Goods#goods.start_time,?Goods#goods.end_time),
?????????ok???=?check_vip(Player#player.vip,?Goods#goods.vip),
?????????ok???=?check_country(Info#info.country,?Goods#goods.country),
?????????ok;
???????false?->
????????{?error,?110}
????end
??catch
????throw:Return?->
????????????Return;
????_:_?->
??????{?error,?unknow}
??end.
?
%%?检查物品数量
check_count(Count,?RequestCount)?when?0?=<?Count?andalso?Count?=<?RequestCount?->??ok;
check_count(_,?_)?->?throw({?error,?110}).
%%?检查职业
check_pro(_Pro,??CONST_SYS_PRO_NULL)?->??ok;
check_pro(Pro,?Pro)?->??ok;
check_pro(_,?_)?->?throw({?error,??EGOODS_PROFESION_NOT_FIT}).
%%?检查性别
check_sex(_Sex,??CONST_SYS_SEX_NULL)?->??ok;
check_sex(Sex,?Sex)?->??ok;
check_sex(_,?_)?->?throw({?error,?110}).
%%?检查等级
check_lv(_Lv,?0)?->??ok;
check_lv(Lv,?RequestLv)?when?Lv?>=?RequestLv?->??ok;
check_lv(_,?_)?->?throw({?error,??EGOODS_LV_NOT_FIT}).
%%?检查有效期
check_time(_Time,?0,?0)?->??ok;
check_time(Time,?0,?EndTime)?when?Time?=<?EndTime?->??ok;
check_time(Time,?StartTime,?0)?when?Time?>=?StartTime?->??ok;
check_time(Time,?StartTime,?EndTime)?when?Time?>=?StartTime?andalso?Time?=<?EndTime?->??ok;
check_time(_,?_,?_)?->?throw({?error,?110}).
%%?检查VIP
check_vip(_Vip,?0)?->??ok;
check_vip(Vip,?RequestVip)?when?Vip?>=?RequestVip?->??ok;
check_vip(_,?_)?->?throw({?error,?110}).
%%?检查国家
check_country(_Country,?0)?->??ok;
check_country(Country,?Country)?->??ok;
check_country(_,?_)?->?throw({?error,?110}).
?2，使用多层匹配，减少嵌套。
Guild= ets_api:lookup(?CONST_ETS_GUILD, GuildId),
GulildPlayer= Player#player.guild,
GuildMember = ets_api:lookup(?CONST_ETS_GUILD_MEMBER, UserId),%%申请人
ApplyList= Guild#ets_guild.apply ,
Apply= lists:keyfind(UserId, #apply.player_id, ApplyList),
case {GulildPlayer#guild.guild_pos >?CONST_GUILD_POSITION_ELDER,
?Guild#ets_guild.num_current >= Guild#ets_guild.num_limit,
?Apply#apply.is_cancel =:= 1,
?is_record(GuildMember, ets_guild_member) andalso GuildMember#ets_guild_member.guild_id > 0} of
{?true,_,_,_} -> %%权限不足
TipPacket = message_api:msg_notice(?TIP_GUILD_DEALAPPLY_NOPREMISS),
misc_packet:send(Player#player.net_pid, TipPacket);
{_,?true,_,_} -> %%成员上限
TipPacket = message_api:msg_notice(?TIP_GUILD_DEALAPPLY_MEMBEROVER),
misc_packet:send(Player#player.net_pid, TipPacket);
{_,_,?true,_} -> %%取消申请
TipPacket = message_api:msg_notice(?TIP_GUILD_DEALAPPLY_CANCELAPPLY),
misc_packet:send(Player#player.net_pid, TipPacket);
{_,_,_,?true} -> %%已加入军团
TipPacket = message_api:msg_notice(?TIP_GUILD_DEALAPPLY_REJOIN),
misc_packet:send(Player#player.net_pid, TipPacket);
{?false,?false,?false,?false} ?->
GuildId = Guild#ets_guild.id,
GuildName = Guild#ets_guild.name,
?
