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How to filter array in subdocument with MongoDB [duplicate]
...ents that match the
condition. The returned elements are in the original order.
db.test.aggregate([
{$match: {"list.a": {$gt:3}}}, // <-- match only the document which have a matching element
{$project: {
list: {$filter: {
input: "$list",
as: "list",
...
When should the volatile keyword be used in C#?
...ly "make sure that the compiler and the
jitter do not perform any code reordering or register caching
optimizations on this variable". It also means "tell the processors to
do whatever it is they need to do to ensure that I am reading the
latest value, even if that means halting other proces...
How to change href of tag on button click through javascript
...Link").onclick = function() {
document.getElementById("abc").href="xyz.php";
return false;
};
</script>
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Python 3 turn range to a list
...
In Pythons <= 3.4 you can, as others suggested, use list(range(10)) in order to make a list out of a range (In general, any iterable).
Another alternative, introduced in Python 3.5 with its unpacking generalizations, is by using * in a list literal []:
>>> r = range(10)
>>> l...
What is the difference between __init__ and __call__?
...hey were functions: pass them to other methods/functions and call them. In order to achieve this, the __call__ class function has to be specialized.
def __call__(self, [args ...])
It takes as an input a variable number of arguments. Assuming x being an instance of the Class X, x.__call__(1, 2)...
How to log out user from web site using BASIC authentication?
... it worked for Chrome and FF. I only had to do an extra "GET" on my logout.php page to clear the $_SESSION.
– urban
Oct 9 '15 at 10:08
2
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Socket.IO Authentication
...
This article (http://simplapi.wordpress.com/2012/04/13/php-and-node-js-session-share-redi/) shows how to
store sessions of the HTTP server in Redis (using Predis)
get these sessions from Redis in node.js by the session id sent in a cookie
Using this code you are able to get t...
How is the undo tree used in Vim?
...rse all of the nodes in the tree in chronological or reverse-chronological order (which can be a bit confusing, because it can jump arbitrarily between undo branches, but if you do g- long enough you'll always get where you need to go eventually). :earlier and :later take a time descriptor like 7m ...
When should I use the Visitor Design Pattern? [closed]
...virtual void hereIsACat(Cat *c) = 0;
};
Then, we modify the hierarchy in order to accept new operations:
class Animal
{ public: virtual void letsDo(Operation *v) = 0; };
class Dog : public Animal
{ public: void letsDo(Operation *v); };
void Dog::letsDo(Operation *v)
{ v->hereIsADog(this); }
...
JSON and XML comparison [closed]
...
Not true, for example, in PHP, JSON uses json.so with no dependencies at 78k, XML on the other hand, needs the xml.so or xmlreader.so at 54k/32k, but also requires the libxml2.so which 1.4megs. More code makes it takes longer to process and use more ...