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Why is “using namespace std;” considered bad practice?
... performance at all. But consider this: you are using two libraries called Foo and Bar:
using namespace foo;
using namespace bar;
Everything works fine, and you can call Blah() from Foo and Quux() from Bar without problems. But one day you upgrade to a new version of Foo 2.0, which now offers a f...
Why do I need to override the equals and hashCode methods in Java?
...hcode, like HashMap and Set. Let's say we have a class like:
public class Foo {
String id;
String whatevs;
Foo(String id, String whatevs) {
this.id = id;
this.whatevs = whatevs;
}
}
We create two instances with the same id:
Foo a = new Foo("id", "something");
Foo...
Is there a way to create a function from a string with javascript?
...
Dynamic function names in JavaScript
Using Function
var name = "foo";
// Implement it
var func = new Function("return function " + name + "(){ alert('hi there!'); };")();
// Test it
func();
// Next is TRUE
func.name === 'foo'
Source: http://marcosc.com/2012/03/dynamic-function-names-in-...
What is Type-safe?
...s, Trying to put an integer in a string
String one = 1;
// Also fails.
int foo = "bar";
This also applies to method arguments, since you are passing explicit types to them:
int AddTwoNumbers(int a, int b)
{
return a + b;
}
If I tried to call that using:
int Sum = AddTwoNumbers(5, "5");
T...
Command line to remove an environment variable from the OS level configuration
...o remove the variable from the current environment (not permanently):
set FOOBAR=
To permanently remove the variable from the user environment (which is the default place setx puts it):
REG delete HKCU\Environment /F /V FOOBAR
If the variable is set in the system environment (e.g. if you origi...
Unicode equivalents for \w and \b in Java regular expressions?
...roperties, too. It now tracks The Unicode Standard, in both RL1.2 and RL1.2a from UTS#18: Unicode Regular Expressions. This is an exciting and dramatic improvement, and the development team is to be commended for this important effort.
Java’s Regex Unicode Problems
The problem with Java regex...
Strange, unexpected behavior (disappearing/changing values) when using Hash default value, e.g. Hash
...rator += when applied to those hashes work as expected.
[1] pry(main)> foo = Hash.new( [] )
=> {}
[2] pry(main)> foo[1]+=[1]
=> [1]
[3] pry(main)> foo[2]+=[2]
=> [2]
[4] pry(main)> foo
=> {1=>[1], 2=>[2]}
[5] pry(main)> bar = Hash.new { [] }
=> {}
[6] pry(main)&g...
Mercurial — revert back to old version and continue from there
..., then you can keep them private. It's very simple: with hg clone --rev 38 foo foo-38 you will get a new local clone that only contains up to revision 38. You can continue working in foo-38 and push the new (good) changesets you create. You'll still have the old (bad) revisions in your foo clone. (Y...
Remove all classes that begin with a certain string
... that does wildcard class removal.
Will optionally add classes too.
$( '#foo' ).alterClass( 'foo-* bar-*', 'foobar' )
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What does the construct x = x || y mean?
...
If title is not set, use 'ERROR' as default value.
More generic:
var foobar = foo || default;
Reads: Set foobar to foo or default.
You could even chain this up many times:
var foobar = foo || bar || something || 42;
...