大约有 49,000 项符合查询结果（耗时：0.0326秒） [XML]
Possibility of duplicate Mongo ObjectId's being generated in two different collections?
...hey are generated on different machines.
Now if you were referring to the _id field in general, we do not require uniqueness across collections so it is safe to reuse the old _id. As a concrete example, if you have two collections, colors and fruits, both could simultaneously have an object like {_...
How to log a method's execution time exactly in milliseconds?
...
I just compared NSDate and mach_absolute_time() at around 30ms level. 27 vs. 29, 36 vs. 39, 43 vs. 45. NSDate was easier to use for me and the results were similar enough not to bother with mach_absolute_time().
– nevan king
...
Concatenating two lists - difference between '+=' and extend()
... function call, which is slightly more expensive in Python than the INPLACE_ADD.
It's really nothing you should be worrying about, unless you're performing this operation billions of times. It is likely, however, that the bottleneck would lie some place else.
...
Using the Underscore module with Node.js
...ms that the first time I use a function from Underscore, it overwrites the _ object with the result of my function call. Anyone know what's going on? For example, here is a session from the node.js REPL:
...
App Inventor 2 EV3超声波传感器教程 · App Inventor 2 中文网
...通过蓝牙连接EV3，读取各种传感器。
已有文档：bluetooth_remote.md 介绍了蓝牙通信。本文聚焦EV3超声波传感器。
EV3组件
添加组件
组件面板 → LEGO MINDSTORMS → **Ev3 Ultrasonic Sensor`
支持的...
Python argparse mutual exclusive group
...
add_mutually_exclusive_group doesn't make an entire group mutually exclusive. It makes options within the group mutually exclusive.
What you're looking for is subcommands. Instead of prog [ -a xxxx | [-b yyy -c zzz]], you'd hav...
Declaring variables inside or outside of a loop
....Test extends java.lang.Object{
public inside.Test();
Code:
0: aload_0
1: invokespecial #1; //Method java/lang/Object."<init>":()V
4: return
public static void main(java.lang.String[]);
Code:
0: invokestatic #2; //Method java/lang/System.currentTimeMillis:()J
3...
pretty-print JSON using JavaScript
...or sure) and not HTML. Output can be seen inside console. You can edit the _variables inside the function adding some more styling.
function JSONstringify(json) {
if (typeof json != 'string') {
json = JSON.stringify(json, undefined, '\t');
}
var
arr = [],
_stri...
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;
...
Command-line Unix ASCII-based charting / plotting tool
...ne, not bar, plots ?)
#!/usr/bin/env python
# -*- coding: utf-8 -*-
from __future__ import division
import numpy as np
__version__ = "2015-01-02 jan denis"
#...............................................................................
def onelineplot( x, chars=u"▁▂▃▄▅▆▇█", se...