history

:help 查看所有可用命令 scala> :help All commands can be abbreviated, e.g., :he instead of :help. :edit <id>|<line> edit history :help [command] print this summary or command-specific help :history [num] show the history (optional num is commands to show) :h? <string> search the history :imports [name name ...] show import history, identifying sources of names :implicits [-v] show the implicits in scope :javap <path|class> disassemble a file or class name :line <id>|<line> place line(s) at the end of history :load <path> interpret lines in a file :paste [-raw] [path] enter paste mode or paste a file

' hello, world ' is usually the first example for any programming language. I've always wondered where this sentence came from and where was it first used. I've once been told that it was the first sentence ever to be displayed on a computer screen, but I've not been able to find any reference to this. So my question is: Where does the practice to use ' hello, world ' as the first example for computer languages originate from? Where was it first used? Update Although the answers are quite interesting, I should have noted that I had read the Wikipedia article. It does answer the question about

We are working with a 3rd party PHP engine that gets regular updates. The releases are kept on a separate branch in git, and our fork is the master branch. This way we'll be able to apply patches to our fork from the new releases of the engine. My problem is, after many commits to our branch, I realized that the initial import of the engine was done with CRLF line endings. I converted every file to LF, but this made a huge commit, with 100k lines removed and 100k lines added, which obviously breaks what we intended to do: easily merge in patches from the factory releases of that 3rd party

当需要从数据库查询的表有上万条记录的时候，一次性查询所有结果会变得很慢，特别是随着数据量的增加特别明显，这时需要使用分页查询。对于数据库分页查询，也有很多种方法和优化的点。 下面简单说一下我知道的一些方法。 准备工作 为了对下面列举的一些优化进行测试，下面针对已有的一张表进行说明。 表名：order_history 描述：某个业务的订单历史表 主要字段：unsigned int id，tinyint(4) int type 字段情况：该表一共37个字段，不包含text等大型数据，最大为varchar(500)，id字段为索引，且为递增。 数据量：5709294 MySQL版本：5.7.16 线下找一张百万级的测试表可不容易，如果需要自己测试的话，可以写shell脚本什么的插入数据进行测试。 以下的 sql 所有语句执行的环境没有发生改变，下面是基本测试结果： select count(*) from orders_history; 返回结果：5709294 三次查询时间分别为： 8903 ms 8323 ms 8401 ms 一般分页查询 一般的分页查询使用简单的 limit 子句就可以实现。limit 子句声明如下： SELECT * FROM table LIMIT [offset,] rows | rows OFFSET offset LIMIT 子句可以被用于指定

Is there a good way to use git to identify all the modified functions in each revision in the history? I've tried using the -p switch, but it doesn't seem to work in the same way that svn's show-c-function parameter works. My assumption is that I'll want to use "git diff HEAD~i HEAD~i-1 -p" for increasing values of i. Am I missing some parameters that will help identify diff's best guess on the functions that were modified? Here's a quick and dirty attempt at what I think you're going for. It does a git log to show all revisions, -p to include the diff in the log, a grep to only include the

1：什么时候需要添加浏览记录 访问商品详情页的时候 2：什么时候取出浏览记录 访问用户个人中心的时候 用户查看商品的历史浏览记录存成什么格式： history_用户id：[商品id，商品id] 添加用户浏览记录： # 添加用户的历史记录history_用户id:[商品id,商品id，商品id]conn = get_redis_connection('default')history_key = 'history_%d' % user.id# 用redis的lrem方法将最早的那一条浏览记录移除掉conn.lrem(history_key, 0, goods_id)# 把goods_id插入到列表的左侧conn.lpush(history_key, goods_id)# 只保存用户最新浏览的5条信息conn.ltrim(history_key, 0, 4)取出浏览记录： # 获取用户的历史浏览记录# 获取redis链接conn = get_redis_connection('default')history_key = 'history_%d' % user.id# 获取用户最新浏览的5个商品的idsku_ids = conn.lrange(history_key, 0, 4) # [2,5,1,6,8]# 从数据库查询用户浏览的商品的具体信息# goods_list =