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How to create enum like type in TypeScript?
...llo"
They are not very useful on their own but can be combined in a type union to create a powerful (and useful) abstraction e.g.:
type CardinalDirection =
"North"
| "East"
| "South"
| "West";
function move(distance: number, direction: CardinalDirection) {
// ...
}
move(1,"N...
How does Java Garbage Collection work with Circular References?
... if they aren't reachable through a chain starting at a garbage collection root, so these objects will be collected. Even though objects may point to each other to form a cycle, they're still garbage if they're cut off from the root.
See the section on unreachable objects in Appendix A: The Truth ...
IN vs OR in the SQL WHERE Clause
...')
WHERE foo = 'a' OR foo = 'b' OR foo = 'c'
According to the manual for MySQL if the values are constant IN sorts the list and then uses a binary search. I would imagine that OR evaluates them one by one in no particular order. So IN is faster in some circumstances.
The best way to know is to p...
Getting View's coordinates relative to the root layout
Can I get a View's x and y position relative to the root layout of my Activity in Android?
10 Answers
...
How do I add the contents of an iterable to a set?
...
@eipxen: There's | for union, & for intersection, and ^ for getting elements that are in one or the other but not both. But in a dynamically typed language where it's sometimes difficult to read the code and know the types of objects flying aro...
Oracle取前N条记录方法 Oracle实现SELECT TOP N的方法 - 数据库(内核) - 清...
...from tablexxx order by xxx desc ) where rownum <= Noracle数据库不支持mysql中limit, top功...select * from ( select * from tablexxx order by xxx desc ) where rownum <= N
oracle数据库不支持mysql中limit, top功能,但可以通过rownum来限制返回的结果集的行数,rownum并不...
Postfix日常维护队列管理 - 更多技术 - 清泛网 - 专注C/C++及内核技术
.../local/httpd/logs/error_log tail -f /usr/local/httpd/logs/suexec_log
mysql相关：tail -f /usr/local/mysql/data/linux.linux.com.err
测试amavisd：amavisd -d config debug-sa
测试spam：spamassassin -D --lint
测试maildrop：maildrop -V 10 -dtest@test.com
Postfix 维护 队列
PHP的函数前加上“@”的作用 - PHP - 清泛IT论坛，有思想、有深度
@是PHP提供的错误信息屏蔽的专用符号。
比如在一个函数前使用@
@mysql_query 不会出现Warning，
而原来mysql_query 在遇到错误时会在页面上访提示Warning。
腾讯云CloudBase接入步骤 - App Inventor 2 拓展 - 清泛IT社区，为创新赋能！
...。2种方式返回access_token，供其他比如数据库、云函数、MySQL、云存储使用。
必备：环境id（EnvironmentId）
匿名登录：设备id，文本类型，自行填入，标识每台设备用的，即设备的身份证，最好不要重复，也最好区分开每台设备...
Clone private git repo with dockerfile
...
# Install software
RUN apt-get install -y git
# Make ssh dir
RUN mkdir /root/.ssh/
# Copy over private key, and set permissions
# Warning! Anyone who gets their hands on this image will be able
# to retrieve this private key file from the corresponding image layer
ADD id_rsa /root/.ssh/id_rsa
#...