Tutorial by Examples: d

Predefined macros are those that the compiler defines (in contrast to those user defines in the source file). Those macros must not be re-defined or undefined by user. The following macros are predefined by the C++ standard: __LINE__ contains the line number of the line this macro is used on, an...

To show some content in a new window, a Stage needs to be created. After creation and initialisation show or showAndWait needs to be called on the Stage object: // create sample content Rectangle rect = new Rectangle(100, 100, 200, 300); Pane root = new Pane(rect); root.setPrefSize(500, 500); ...

# app/channels/appearance_channel.rb class NotificationsChannel < ApplicationCable::Channel def subscribed stream_from "notifications" end def unsubscribed end def notify(data) ActionCable.server.broadcast "notifications", { title: 'New things!', ...

app/assets/javascripts/channels/notifications.coffee App.notifications = App.cable.subscriptions.create "NotificationsChannel", connected: -> # Called when the subscription is ready for use on the server $(document).on "change", "input", (e)=> ...

Java-like enumerations can be created by extending Enumeration. object WeekDays extends Enumeration { val Mon, Tue, Wed, Thu, Fri, Sat, Sun = Value } def isWeekend(day: WeekDays.Value): Boolean = day match { case WeekDays.Sat | WeekDays.Sun => true case _ => false } isWeekend...

An alternative to extending Enumeration is using sealed case objects: sealed trait WeekDay object WeekDay { case object Mon extends WeekDay case object Tue extends WeekDay case object Wed extends WeekDay case object Thu extends WeekDay case object Fri extends WeekDay case objec...

Functions can either be named or unnamed (anonymous functions): var namedSum = function sum (a, b) { // named return a + b; } var anonSum = function (a, b) { // anonymous return a + b; } namedSum(1, 3); anonSum(1, 3); 4 4 But their names are private to their own scope: ...

To avoid verbose null checking, the ?. operator has been introduced in the language. The old verbose syntax: If myObject IsNot Nothing AndAlso myObject.Value >= 10 Then Can be now replaced by the concise: If myObject?.Value >= 10 Then The ? operator is particularly powerful when you...

Freddy is a JSON parsing library maintained by Big Nerd Ranch. It has three principal benefits: Type Safety: Helps you work with sending and receiving JSON in a way that prevents runtime crashes. Idiomatic: Takes advantage of Swift's generics, enumerations, and functional features, without...

Getting current date is very easy. You get NSDate object of current date in just single line as follows: Swift var date = NSDate() Swift 3 var date = Date() Objective-C NSDate *date = [NSDate date];

The number of seconds from the current date and time for the new date. Use a negative value to specify a date before the current date. For doing this we have a method named dateWithTimerIntervalSinceNow(seconds: NSTimeInterval) -> NSDate (Swift) or + (NSDate*)dateWithTimeIntervalSinceNow:(NSTime...

There are 4 methods for comparing dates: Swift isEqualToDate(anotherDate: NSDate) -> Bool earlierDate(anotherDate: NSDate) -> NSDate laterDate(anotherDate: NSDate) -> NSDate compare(anotherDate: NSDate) -> NSComparisonResult Objective-C - (BOOL)isEqualToDate:(NSDate *)anothe...

Get the description of an specific property in an object. var sampleObject = { hello: 'world' }; Object.getOwnPropertyDescriptor(sampleObject, 'hello'); // Object {value: "world", writable: true, enumerable: true, configurable: true}

Swift let alert = UIAlertController(title: "Hello", message: "Welcome to the world of iOS", preferredStyle: UIAlertControllerStyle.alert) let defaultAction = UIAlertAction(title: "OK", style: UIAlertActionS...

Custom Font Support Applications that want to use custom fonts can now include those fonts in their application bundle and register those fonts with the system by including the UIAppFonts key in their Info.plist file. The value of this key is an array of strings identifying the font files in the ...

To get the timestamp in seconds Math.floor((new Date().getTime()) / 1000)

getPreferences(int) returns the preferences saved by Activity's class name as described in the docs : Retrieve a SharedPreferences object for accessing preferences that are private to this activity. This simply calls the underlying getSharedPreferences(String, int) method by passing in this acti...

The following is an excerpt from Gradle - What is a non-zero exit value and how do I fix it?, see it for the full discussion. Let's say you are developing an application and you get some Gradle error that appears that generally will look like so. :module:someTask FAILED FAILURE: Build failed with...

To spawn a new process in which you need unbuffered output (e.g. long-running processes which might print output over a period of time rather than printing and exiting immediately), use child_process.spawn(). This method spawns a new process using a given command and an array of arguments. The retu...

<p contenteditable>This is an editable paragraph.</p> Upon clicking on the paragraph, the content of it can be edited similar to an input text field. When the contenteditable attribute is not set on an element, the element will inherit it from its parent. So all child text of a conte...