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How to exit from PostgreSQL command line utility: psql
...Tab
google.com
Quit PSQL
\q
I think veterans of the psql command line usually shorten that to just:
\q
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What is a Maven artifact?
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An artifact is a file, usually a JAR, that gets deployed to a Maven repository.
A Maven build produces one or more artifacts, such as a compiled JAR and a "sources" JAR.
Each artifact has a group ID (usually a reversed domain name, like com.example....
Default argument values in JavaScript functions [duplicate]
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In javascript you can call a function (even if it has parameters) without parameters.
So you can add default values like this:
function func(a, b){
if (typeof(a)==='undefined') a = 10;
if (typeof(b)==='undefined') b = 20;
//your code
}
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What does set -e mean in a bash script?
...shell functions, so if you have functions, set -o errtrace or set -E will allow you to just set the trap once and apply it globally.
– ykay
Jul 17 '15 at 18:21
32
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Using multiple let-as within a if-statement in Swift
...e code inside the if-let block won't be executed.
Note: the clauses don't all have to be 'let' clauses, you can have any series of boolean checks separated by commas.
For example:
if let latitudeDouble = latitude as? Double, importantThing == true {
// latitudeDouble is non-optional in here ...
What is a Manifest in Scala and when do you need it?
Since Scala 2.7.2 there is something called Manifest which is a workaround for Java's type erasure. But how does Manifest work exactly and why / when do you need to use it?
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encryption/decryption with multiple keys
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GnuPG and PGP clients in general usually encrypt the actual data with a symmetric key called a "session key". The session key is then encrypted with each "recipient key" (i.e. the ones you specify with -r/--recipient). This is sometimes referred to as a hybri...
Why is there no GIL in the Java Virtual Machine? Why does Python need one so bad?
I'm hoping someone can provide some insight as to what's fundamentally different about the Java Virtual Machine that allows it to implement threads nicely without the need for a Global Interpreter Lock (GIL), while Python necessitates such an evil.
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What is the purpose of Node.js module.exports and how do you use it?
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module.exports is the object that's actually returned as the result of a require call.
The exports variable is initially set to that same object (i.e. it's a shorthand "alias"), so in the module code you would usually write something like this:
let myFunc1 = func...
How to return smart pointers (shared_ptr), by reference or by value?
...ilers. I know for a fact that Visual C++ compilers implement RVO even when all optimizations are turned off. And with C++11's move semantics, this concern is even less relevant. (But the only way to be sure is to profile and experiment.)
If you're still not convinced, Dave Abrahams has an article t...