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How to use concerns in Rails 4
...4 project generator now creates the directory "concerns" under controllers and models. I have found some explanations about how to use routing concerns, but nothing about controllers or models.
...
Difference between reduce and foldLeft/fold in functional programming (particularly Scala and Scala
Why do Scala and frameworks like Spark and Scalding have both reduce and foldLeft ? So then what's the difference between reduce and fold ?
...
How to check if PHP array is associative or sequential?
...kurO.
For the second question (checking whether the array is zero-indexed and sequential), you can use the following function:
function isAssoc(array $arr)
{
if (array() === $arr) return false;
return array_keys($arr) !== range(0, count($arr) - 1);
}
var_dump(isAssoc(['a', 'b', 'c'])); //...
How can I make setInterval also work when a tab is inactive in Chrome?
...
On most browsers inactive tabs have low priority execution and this can affect JavaScript timers.
If the values of your transition were calculated using real time elapsed between frames instead fixed increments on each interval, you not only workaround this issue but also can achiev...
How can prepared statements protect from SQL injection attacks?
...
The idea is very simple - the query and the data are sent to the database server separately.
That's all.
The root of the SQL injection problem is in the mixing of the code and the data.
In fact, our SQL query is a legitimate program.
And we are creating s...
How do I recover/resynchronise after someone pushes a rebase or a reset to a published branch?
...he bookmark of course, if you look up the pre-rebase origin/foo commit ID, and use that.
This is also how you deal with the situation where you forgot to make a bookmark before fetching. Nothing is lost – you just need to check the reflog for the remote branch:
git reflog show origin/foo | awk '...
Validate phone number with JavaScript
I found this code in some website, and it works perfectly. It validates that the phone number is in one of these formats:
(123) 456-7890 or 123-456-7890
...
How do I measure time elapsed in Java? [duplicate]
...answers posted so far are quite right.
If you are measuring elapsed time, and you want it to be correct, you must use System.nanoTime(). You cannot use System.currentTimeMillis(), unless you don't mind your result being wrong.
The purpose of nanoTime is to measure elapsed time, and the purpose of...
Why can't I initialize non-const static member or static array in class?
...
Why I can't initialize static data members in class?
The C++ standard allows only static constant integral or enumeration types to be initialized inside the class. This is the reason a is allowed to be initialized while others are not.
Reference:
C++03 9.4.2 Static data members
§4
...
How do you check if a JavaScript Object is a DOM Object?
...function isElement(obj) {
try {
//Using W3 DOM2 (works for FF, Opera and Chrome)
return obj instanceof HTMLElement;
}
catch(e){
//Browsers not supporting W3 DOM2 don't have HTMLElement and
//an exception is thrown and we end up here. Testing some
//properties that all eleme...