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Dictionaries and default values
...collections import defaultdict
a = defaultdict(lambda: "default", key="some_value")
a["blabla"] => "default"
a["key"] => "some_value"
You can pass any ordinary function instead of lambda:
from collections import defaultdict
def a():
return 4
b = defaultdict(a, key="some_value")
b['absent...
Send message to specific client with socket.io and node.js
..."I'm the master", function() {
// Save the socket id to Redis so that all processes can access it.
client.set("mastersocket", socket.id, function(err) {
if (err) throw err;
console.log("Master socket is now" + socket.id);
});
});
socket.on("message to master", function(...
Differences between socket.io and websockets
...ds can i conclude that the following statement is wrong? Socket.IO is actually more than a layer over WebSockets.
– Pulak Kanti Bhattacharyya
Aug 9 '14 at 15:18
3
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Apply formula to the entire column
I'm trying to recode all the zip code from Column A into Column B with the formula:
10 Answers
...
What's the reason I can't create generic array types in Java?
What's the reason why Java doesn't allow us to do
17 Answers
17
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内存优化总结:ptmalloc、tcmalloc和jemalloc - 操作系统(内核) - 清泛网 - ...
...序本身的程序特性进行优化， 比如使用引用计数std::shared_ptr，apache的内存池方式等等。
当然应用程序也可以直接使用系统调用从内核分配内存，自己根据程序特性来维护内存，但是会大大增加开发成本。
本文主要介绍了glibc...
What does PHP keyword 'var' do?
...tants states that var must not be used, and visibility must be declared on all properties.
– Charles Wood
Nov 11 '19 at 14:23
...
File content into unix variable with newlines
...
The assignment does not remove the newline characters, it's actually the echo doing this. You need simply put quotes around the string to maintain those newlines:
echo "$testvar"
This wil give the result you want. See the following transcript for a demo:
pax> cat num1.txt ; x=$(cat...
What does “|=” mean? (pipe equal operator)
...ults | Notification.DEFAULT_SOUND;
where | is the bit-wise OR operator.
All operators are referenced here.
A bit-wise operator is used because, as is frequent, those constants enable an int to carry flags.
If you look at those constants, you'll see that they're in powers of two :
public static...
How to search DOM elements using XPath or CSS selectors in Chrome Developer Tools?
...ction accepts a second optional argument, context. $x(xpath, context) This allows you to select a particular iframe content, for example, and run an xpath query against it. So for the first iframe: myframe = document.getElementsByTagName("iframe")[0].contentWindow.document.body; #to xpath query that...