Common usage of lock is a critical section.
In the following example ReserveRoom is supposed to be called from different threads. Synchronization with lock is the simplest way to prevent race condition here. Method body is surrounded with lock which ensures that two or more threads cannot execute i...
Private inheritance is useful when it is required to restrict the public interface of the class:
class A {
public:
int move();
int turn();
};
class B : private A {
public:
using A::turn;
};
B b;
b.move(); // compile error
b.turn(); // OK
This approach efficiently pr...
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);
...
If you have an existing class that you'd like to use, perform Step 2 and then skip to Step 5. (For some cases, I had to add an explicit #import <Foundation/Foundation.h to an older ObjC File)
Step 1: Add Objective-C Implementation -- .m
Add a .m file to your class, and name it CustomObje...
Step 1: Create New Swift Class
Add a .swift file to your project, and name it MySwiftObject.swift
In MySwiftObject.swift:
import Foundation
class MySwiftObject : NSObject {
var someProperty: AnyObject = "Some Initializer Val"
init() {}
func someFunction(someArg...
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...
Creating a Snackbar can be done as follows:
Snackbar.make(view, "Text to display", Snackbar.LENGTH_LONG).show();
The view is used to find a suitable parent to use to display the Snackbar. Typically this would be a CoordinatorLayout that you've defined in your XML, which enables adding ...
The String List passed as a parameter to the share() method contains the paths of all the files you want to share.
It basically loops through the paths, adds them to Uri, and starts the Activity which can accept Files of this type.
public static void share(AppCompatActivity context,List<Strin...
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...
The NameOf operator resolves namespaces, types, variables and member names at compile time and replaces them with the string equivalent.
One of the use cases:
Sub MySub(variable As String)
If variable Is Nothing Then Throw New ArgumentNullException("variable")
End Sub
The old sy...
This new feature makes the string concatenation more readable. This syntax will be compiled to its equivalent String.Format call.
Without string interpolation:
String.Format("Hello, {0}", name)
With string interpolation:
$"Hello, {name}"
The two lines are equivalent and ...
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...
