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ZMQ: 基本原理 - 开源 & Github - 清泛网 - 专注C++内核技术
... 为了强化这个原则，ØMQ严格地分离拓扑的建立（zmq_bind,zmq_connect）和真实消息的传递（zmq_send,zmq_rev)。 前者同底层的传输地址协同工作，比如IP地址，而后者仅仅使用处理器（文件描述符）去定位具体的拓扑： /* Topology esta...
Haskell Type vs Data Constructor
...erstanding type constructors and data constructors. For example, I don't really understand the difference between this:
6 A...
How do I get the last inserted ID of a MySQL table in PHP?
...ng PDO, use PDO::lastInsertId.
If you're using Mysqli, use mysqli::$insert_id.
If you're still using Mysql:
Please, don't use mysql_* functions in new code. They are no longer maintained and are officially deprecated. See the red box? Learn about prepared statements instead, and use PDO or MyS...
How to explicitly discard an out argument?
...ublic void PrintXCoordinate(Point p)
{
p.GetCoordinates(out int x, out _); // I only care about x
WriteLine($"{x}");
}
Source: https://blogs.msdn.microsoft.com/dotnet/2017/03/09/new-features-in-c-7-0/
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How to convert a unix timestamp (seconds since epoch) to Ruby DateTime?
...cessary instead of DateTime. So use Time.strptime("1318996912345",'%Q').to_f and you will see the milliseconds preserved, while DateTime.strptime("1318996912345",'%Q').to_f does not preserve it.
– skensell
Feb 22 '17 at 15:20
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Nullable Foreign Key bad practice?
... read.
Only if you know better than Chris Date "what first normal form really means". If x and y are both nullable, and indeed in some row x and y are both null, then WHERE x=y does not yield true. This proves beyond reasonable doubt that null is not a value (because any real value is always equ...
Adding Only Untracked Files
...where I've interactively added some updates to the index and I want to add all of the untracked files to that index before I commit.
...
What does the “@” symbol mean in reference to lists in Haskell?
...hout the @, you'd have to choose between (1) or (2):(3).
This syntax actually works for any constructor; if you have data Tree a = Tree a [Tree a], then t@(Tree _ kids) gives you access to both the tree and its children.
s...
Changes in import statement python3
...a single function. In Python 2 you were permitted to be semi-lazy:
def sin_degrees(x):
from math import *
return sin(degrees(x))
Note that it already triggers a warning in Python 2:
a.py:1: SyntaxWarning: import * only allowed at module level
def sin_degrees(x):
In modern Python 2 co...
How to read environment variables in Scala
...
I would also prefer Properties. It allows to retrieve Optionals, and has names for commonly used properties.
– ppopoff
Dec 17 '15 at 14:46
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