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Javascript: best Singleton pattern [duplicate]
... return instance;
}
this.instance = this;
}
foo() {
// ...
}
}
console.log(new Singleton() === new Singleton());
(2) ES6 Version
class Singleton {
constructor() {
const instance = this.constructor.instance;
if (instance) {
...
LINQ: Select an object and change some properties without creating a new object
...Q expression example.
var query = someList.Select(x => { x.SomeProp = "foo"; return x; })
What this does is use an anonymous method vs and expression. This allows you to use several statements in one lambda. So you can combine the two operations of setting the property and returning the obje...
Best way to parse command-line parameters? [closed]
...t.OptionParser[Config]("scopt") {
head("scopt", "3.x")
opt[Int]('f', "foo") action { (x, c) =>
c.copy(foo = x) } text("foo is an integer property")
opt[File]('o', "out") required() valueName("<file>") action { (x, c) =>
c.copy(out = x) } text("out is a required file prope...
Why does string::compare return an int?
...
if I was to design a compare method that compares two objects of type Foo and I only wanted to return -1, 0 or 1, would using short or char generally be a good idea?
It would be ok idea. A better way would be to return a bool (if only want to compare if equal), or enum (for more information) ...
How to make an enum conform to a protocol in Swift?
...lip between cases as follows:
enum SimpleEnum: ExampleProtocol {
case Foo, Bar
var simpleDescription: String {
get {
let value = self == .Foo
? "Foo"
: "Bar"
return "A simple \(value) enum."
}
}
mutating func adjust() {
self ...
Best way to check for “empty or null value”
...lesce(stringexpression, '') = ' ' AS coalesce3
FROM (
VALUES
('foo'::char(5))
, ('')
, (' ') -- not different from '' in char(n)
, (NULL)
) sub(stringexpression);
Result:
stringexpression | base_test | test1 | test2 | coalesce1 | coalesce2 | coalesce3
---...
File path to resource in our war/WEB-INF folder?
...ntext = getContext();
String fullPath = context.getRealPath("/WEB-INF/test/foo.txt");
http://tomcat.apache.org/tomcat-5.5-doc/servletapi/javax/servlet/ServletContext.html#getRealPath(java.lang.String)
That will get you the full system path to the resource you are looking for. However, that won't...
JavaScript equivalent of PHP’s die
... from within a function in the scope. This means you can't do stuff like:
foo: { // this doesn't work
(function() {
break foo;
}());
}
You can do something similar though with functions:
function myFunction() {myFunction:{
// you can now use break myFunction; instead of return;
}}
...
What are the recommendations for html tag?
...hors like <a href="#anchor">, query string anchors like <a href="?foo=bar"> and path fragment anchors like <a href=";foo=bar">, with the <base> tag you're basically declaring all relative links relative to it, including those kind of anchors. None of the relative links are re...
What is the scope of variables in JavaScript?
...nction expressions are scoped only to the expression itself:
(function foo() { console.log(foo) })()
console.log(typeof foo) // undefined, because `foo` is scoped to its own expression
In non-strict mode, implicitly defined properties on the global object are globally scoped. In strict mod...