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Why is Scala's immutable Set not covariant in its type?
...ameter of type A due to the contravariance of functions. Set could potentially be contravariant in A, but this too causes issues when you want to do things like this:
def elements: Iterable[A]
In short, the best solution is to keep things invariant, even for the immutable data structure. You'll...
Get a random item from a JavaScript array [duplicate]
... not a valid substitution for Math.floor. Using round would cause accidentally referencing an undefined index, say in the case Math.random() is 0.95 and items.length is 5. Math.round(0.95*5) is 5, which would be an invalid index. floor(random) will always be zero in your example.
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What is the difference between JSON and Object Literal Notation?
...
Lets clarify first what JSON actually is. JSON is a textual, language-independent data-exchange format, much like XML, CSV or YAML.
Data can be stored in many ways, but if it should be stored in a text file and be readable by a computer, it needs to follow ...
How do I log errors and warnings into a file?
How do I turn on all error and warnings and log them to a file, but to set up all of that within the script (not changing anything in php.ini)?
...
How to find the operating system version using JavaScript?
...
If you list all of window.navigator's properties using
console.log(navigator);
You'll see something like this
# platform = Win32
# appCodeName = Mozilla
# appName = Netscape
# appVersion = 5.0 (Windows; en-US)
# language = en-US
# ...
What does 'require: false' in Gemfile mean?
...
This means install the gem, but do not call require when you start Bundler. So you will need to manually call
require "whenever"
if you want to use the library.
If you were to do
gem "whenever", require: "whereever"
then bundler woul...
Django templates: verbose version of a choice
... (universal), though - unless you know a way to iterate in a template over all get_FOO_display methods of a model object :) I'm a bit too lazy for writing non-generic templates ;) Moreover, the docs say it's a model instance's method. Therefore it'd have to be a model form bound to an existing obj...
Cast Object to Generic Type for returning
... |
edited Mar 1 '18 at 13:32
answered Jan 25 '13 at 15:19
S...
NSNotificationCenter addObserver in Swift
...)
NSNotificationCenter.defaultCenter().removeObserver(self) // Remove from all notifications being observed
Method handler for received Notification
func methodOfReceivedNotification(notification: NSNotification) {
// Take Action on Notification
}
Annotate either the class or the target metho...
Eclipse - no Java (JRE) / (JDK) … no virtual machine
... (the first one referenced by your PATH)
Three things to remember:
"Installing" a JRE or a JDK can be as simple as unzipping or copying it from another computer: there is no special installation steps, and you can have as many different JVM versions (1.4, 5.0, 6.0...) as you want, "installed" (co...