大约有 40,000 项符合查询结果（耗时：0.0424秒） [XML]
Determine what attributes were changed in Rails after_save callback?
I'm setting up an after_save callback in my model observer to send a notification only if the model's published attribute was changed from false to true. Since methods such as changed? are only useful before the model is saved, the way I'm currently (and unsuccessfully) trying to do so is as fol...
关于php的socket初探 - PHP - 清泛IT论坛，有思想、有深度
...塞的古老模型：属于同步阻塞 IO 模型，代码如下：
socket_server.php
<?php
/**
* SocketServer Class
* By James.Huang <shagoo#gmail.com>
**/
set_time_limit(0);
class SocketServer
{
private stati...
Reference: mod_rewrite, URL rewriting and “pretty links” explained
...rver doesn't have to be Apache, there are many other web servers which are all just programs which run persistently and are attached to a port which respond to HTTP requests. You can write one yourself. This paragraph was intended to divorce you from any notion that URLs directly equal files, which ...
Create singleton using GCD's dispatch_once in Objective-C
...er here: instancetype
+ (instancetype)sharedInstance
{
static dispatch_once_t once;
static id sharedInstance;
dispatch_once(&once, ^
{
sharedInstance = [self new];
});
return sharedInstance;
}
+ (Class*)sharedInstance
{
static dispatch_once_t once;
...
LINQ - Full Outer Join
...
I don't know if this covers all cases, logically it seems correct. The idea is to take a left outer join and right outer join then take the union of the results.
var firstNames = new[]
{
new { ID = 1, Name = "John" },
new { ID = 2, Name = "Sue"...
Plotting time in Python with Matplotlib
...erstand why this is the 5th question I've encountered where no one has actually TRIED using a scatter plot - it doesn't work. Type Error - invalid type promotion.
– dwanderson
Oct 5 '16 at 16:21
...
How to do parallel programming in Python?
For C++, we can use OpenMP to do parallel programming; however, OpenMP will not work for Python. What should I do if I want to parallel some parts of my python program?
...
How do I remove  from the beginning of a file?
...oks fine when I open it using gedit , but when it's read by PHP (to merge all the CSS files into one), this CSS has the following characters prepended to it: 
...
How do I print a double value with full precision using cout?
...
Is the really the right answer? When I manually use a high number, I can print out as many as 51 digits of approximated e, but with cout.precision(numeric_limits<double>::digits10 + 2); I only get 16....
– ...
Class vs. static method in JavaScript
... instantiate an object from that function using the new keyword which will allow you to create something similar to a class in a standard OOP language.
I'd suggest ignoring __proto__ most of the time because it has poor cross browser support, and instead focus on learning about how prototype works....