A class designed to be inherited-from is called a Base class. Care should be taken with the special member functions of such a class.
A class designed to be used polymorphically at run-time (through a pointer to the base class) should declare the destructor virtual. This allows the derived parts of...
Bear in mind that declaring a destructor inhibits the compiler from generating implicit move constructors and move assignment operators. If you declare a destructor, remember to also add appropriate definitions for the move operations.
Furthermore, declaring move operations will suppress the genera...
When creating a recyclerview with a gridlayout layout manager you have to specify the span count in the constructor. Span count refers to the number of columns. This is fairly clunky and doesn't take into account larger screen sizes or screen orientation. One approach is to create multiple layouts f...
Define your class that will represent your custom error.
public class ErrorDto
{
public int Code { get; set; }
public string Message { get; set; }
// other fields
public override string ToString()
{
return JsonConvert.SerializeObject(this);
}
}
Then put nex...
The idea is to use HttpContext.Response.OnStarting callback, as this is the last event that is fired before the headers are sent. Add the following to your middleware Invoke method.
public async Task Invoke(HttpContext context)
{
context.Response.OnStarting((state) =>
{
if ...
A shell script is a very versatile way to extend your build to basically anything you can think of.
As an exmaple, here is a simple script to compile protobuf files and add the result java files to the source directory for further compilation:
def compilePb() {
exec {
// NOTICE: grad...
With the rgdal package it is possible to import and export shapfiles with R.
The function readOGR can be used to imports shapfiles. If you want to import a file from e.g. ArcGIS the first argument dsn is the path to the folder which contains the shapefile. layer is the name of the shapefile without...
The packages foreign and haven can be used to import and export files from a variety of other statistical packages like Stata, SPSS and SAS and related software. There is a read function for each of the supported data types to import the files.
# loading the packages
library(foreign)
library(have...
The class we are going to test is:
public class Service {
private Collaborator collaborator;
public Service(Collaborator collaborator) {
this.collaborator = collaborator;
}
public String performService(String input) {
return collaborator.transformStri...
Enumerable is the most popular module in Ruby. Its purpose is to provide you with iterable methods like map, select, reduce, etc. Classes that use Enumerable include Array, Hash, Range.
To use it, you have to include Enumerable and implement each.
class NaturalNumbers
include Enumerable
de...
Comparable is one of the most popular modules in Ruby. Its purpose is to provide with convenience comparison methods.
To use it, you have to include Comparable and define the space-ship operator (<=>):
class Rectangle
include Comparable
def initialize(a, b)
@a = a
@b = b
...
An unnamed namespace can be used to ensure names have internal linkage (can only be referred to by the current translation unit). Such a namespace is defined in the same way as any other namespace, but without the name:
namespace {
int foo = 42;
}
foo is only visible in the translation uni...
Statement-level parallel hints are the easiest:
SELECT /*+ PARALLEL(8) */ first_name, last_name FROM employee emp;
Object-level parallel hints give more control but are more prone to errors; developers often forget to use the alias instead of the object name, or they forget to include some objec...
In C#, there are two different kinds of equality: reference equality and value equality. Value equality is the commonly understood meaning of equality: it means that two objects contain the same values. For example, two integers with the value of 2 have value equality. Reference equality means that ...
There are few approaches available there:
You can subscribe for keyboard appearance events notifications and change offset manually:
//Swift 2.0+
override func viewDidLoad() {
super.viewDidLoad()
NSNotificationCenter.defaultCenter().addObserver(self, selector: #selector(YourVCClas...
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...
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)=>
...
