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Difference between fold and reduce?
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So basically instead of doing fold, you can simply add that initial value to the start of the list and do reduce? What's the point of fold then?
– Pacerier
Feb 7 '17 at 9:42
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When to use reinterpret_cast?
...time hence the word static . This is the cast the C++ compiler uses internally for implicit casts also.
11 Answers
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How to implement an ordered, default dict? [duplicate]
...deredDict() and defaultdict() from collections in one object, which shall be an ordered, default dict .
Is this possible?
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What does %w(array) mean?
....], curly braces %w{...} or even something like exclamation marks %w!...!. All of these have the same behavior (returning an array).
– ryanb
Aug 13 '09 at 21:40
146
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Best way to iterate through a Perl array
...ay elements occurs. ($_ is aliased to the element in #1, but #2 and #3 actually copy the scalars from the array.)
#5 might be similar.
In terms memory usage: They're all the same except for #5.
for (@a) is special-cased to avoid flattening the array. The loop iterates over the indexes of the array...
In Python how should I test if a variable is None, True or False
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a = 'foo' if a: print 'its true' a is not actually TRUE, it's just not none
– wesm
Apr 3 '15 at 21:06
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New self vs. new static
...the first method, whereas static is bound to the called class (also see get_called_class()).
class A {
public static function get_self() {
return new self();
}
public static function get_static() {
return new static();
}
}
class B extends A {}
echo get_class(B::ge...
List all the files that ever existed in a Git repository
Do you have a clean way to list all the files that ever existed in specified branch?
4 Answers
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What does the 'b' character do in front of a string literal?
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Actually, if you've imported unicode_literals from __future__, this will "reverse" the behavior for this particular string (in Python 2.x)
– Romuald Brunet
Mar 14 '13 at 16:27
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Creating the Singleton design pattern in PHP5
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/**
* Singleton class
*
*/
final class UserFactory
{
/**
* Call this method to get singleton
*
* @return UserFactory
*/
public static function Instance()
{
static $inst = null;
if ($inst === null) {
$inst = new UserFactory();
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