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MongoDB: Combine data from multiple collections into one..how?
..., reduce;
db.users_comments.remove();
// setup sample data - wouldn't actually use this in production
db.users.remove();
db.comments.remove();
db.users.save({firstName:"Rich",lastName:"S",gender:"M",country:"CA",age:"18"});
db.users.save({firstName:"Rob",lastName:"M",gender:"M",country:"US",age:"25...
How to find memory leak in a C++ code/project?
...e software tools
1
Understand the operator basics. The C++ operator new allocates heap memory. The delete operator frees heap memory. For every new, you should use a delete so that you free the same memory you allocated:
char* str = new char [30]; // Allocate 30 bytes to house a string.
delete ...
How do I achieve the theoretical maximum of 4 FLOPs per cycle?
... while (i < 1000){
// Here's the meat - the part that really matters.
r0 = _mm_mul_pd(r0,rC);
r1 = _mm_add_pd(r1,rD);
r2 = _mm_mul_pd(r2,rE);
r3 = _mm_sub_pd(r3,rF);
r4 = _mm_mul_pd(r4,rC);
r5 = _mm_add_pd(r5...
Explaining Python's '__enter__' and '__exit__'
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Using these magic methods (__enter__, __exit__) allows you to implement objects which can be used easily with the with statement.
The idea is that it makes it easy to build code which needs some 'cleandown' code executed (think of it as a try-finally block). Some more ex...
Regex to Match Symbols: !$%^&*()_+|~-=`{}[]:";'?,./
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The regular expression for this is really simple. Just use a character class. The hyphen is a special character in character classes, so it needs to be first:
/[-!$%^&*()_+|~=`{}\[\]:";'<>?,.\/]/
You also need to escape the other regular expressio...
How does deriving work in Haskell?
Algebraic Data Types (ADTs) in Haskell can automatically become instances of some typeclasse s (like Show , Eq ) by deriving from them.
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UICollectionView Set number of columns
...[self.myCollectionView.collectionViewLayout invalidateLayout];
}
Additionally, here are 2 really good tutorials on UICollectionViews:
http://www.raywenderlich.com/22324/beginning-uicollectionview-in-ios-6-part-12
http://skeuo.com/uicollectionview-custom-layout-tutorial
...
history.replaceState() example?
...ight be to keep using replaceState() and simply set the document title manually document.title = "title"
– newshorts
Nov 7 '16 at 18:49
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Debugging in Clojure? [closed]
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There's also dotrace, which allows you to look at the inputs and outputs of selected functions.
(use 'clojure.contrib.trace)
(defn fib[n] (if (< n 2) n (+ (fib (- n 1)) (fib (- n 2)))))
(dotrace [fib] (fib 3))
produces the output:
TRACE t4425: (f...
Include all existing fields and add new fields to document
...t aggregation stage where I can instruct it to add a new field and include all existing fields, without having to list all the existing fields.
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