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Why are arrays covariant but generics are invariant?
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153
Via wikipedia:
Early versions of Java and C# did not include generics (a.k.a. parametric pol...
Run a single migration file
... of the ruby file:
rails console
>> require "db/migrate/20090408054532_add_foos.rb"
>> AddFoos.up
Note: newer versions of rails may require AddFoos.new.up rather than AddFoos.up.
An alternative way (without IRB) which relies on the fact that require returns an array of class names:
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Maximum size of an Array in Javascript
...ccording to the ECMA-262 5th Edition specification is bound by an unsigned 32-bit integer due to the ToUint32 abstract operation, so the longest possible array could have 232-1 = 4,294,967,295 = 4.29 billion elements.
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Is volatile expensive?
After reading The JSR-133 Cookbook for Compiler Writers about the implementation of volatile, especially section "Interactions with Atomic Instructions" I assume that reading a volatile variable without updating it needs a LoadLoad or a LoadStore barrier. Further down the page I see that LoadLoad ...
When should I use nil and NULL in Objective-C?
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13
technically, they are exactly equal, you can send messages to both nil and to NULL. Idiomatically though nil is usually used to represent an...
How do I properly escape quotes inside HTML attributes?
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355
" is the correct way, the third of your tests:
<option value="&quot;asd">t...
POST request via RestTemplate in JSON
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edited Sep 6 '18 at 20:37
arghtype
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String Resource new line /n not possible?
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382
use a blackslash not a forwardslash. \n
<?xml version="1.0" encoding="utf-8"?>
<reso...
PHP: How to generate a random, unique, alphanumeric string for use in a secret link?
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30 Answers
30
Active
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In SQL, what's the difference between count(column) and count(*)?
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236
count(*) counts NULLs and count(column) does not
[edit] added this code so that people can run...