Tutorial by Examples: w

Instantiating class with no parameter: {} vs ()

Let's say we have a class MyClass with no constructor argument: class MyClass In Scala we can instantiate it using below syntax: val obj = new MyClass() Or we can simply write: val obj = new MyClass But, if not paid attention, in some cases optional parenthesis may produce some unexpecte...

Scala Language • Classes and Objects

IronPython is written in pure c#

IronPython is completly written using managed .net (c#) code. So all builtin python methods and libraries (such as next(), int(), etc.) are writtin in .net. This example shows the implementation of len() for a list of different types (only a few): .... public static int len([NotNull]List/*!*/ l...

ironpython • Difference between Python and IronPython

Basic View

index.html <html> <head> <title>Angular-UI Router Example</title> <script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/angular.js/1.4.9/angular.js"></script> <script type="text/java...

angular-ui-router • Getting started with angular-ui-router

Mistakenly writing = instead of == when comparing

The = operator is used for assignment. The == operator is used for comparison. One should be careful not to mix the two. Sometimes one mistakenly writes /* assign y to x */ if (x = y) { /* logic */ } when what was really wanted is: /* compare if x is equal to y */ if (x == y) { ...

C Language • Common pitfalls

Context switching

The two possible ways of issuing a context.become (replacing or adding the new behavior) are offered separately to enable a clutter-free notation of nested receives: val a = actor(new Act { become { // this will replace the initial (empty) behavior case "info" ⇒ sender() ! "A...

akka • Actor DSL

Draw a diagonal blue line using the L path command

SVG • Paths

Draw a horizontal orange line using the H drawing command

SVG • Paths

Draw a red cross using l (relative line) path commands

SVG • Paths

Draw a vertical green line using the V path command

SVG • Paths

Create a UICollectionView

Initialize a UICollectionView with a CGRect frame: Swift: let collection = UICollectionView(frame: CGRect(x: 0, y: 0, width: 200, height: 21)) Objective C: UICollectionView *collection = [[UICollectionView alloc] initWithFrame:CGRectMake(0, 0, 200, 21)]; You can also create a UICollectionVi...

iOS • UICollectionView

UICollectionView - Datasource

Every collection view must have a Datasource object. The Datasource object is the content that your app will display within the UICollectionView. At a minimum, all Datasource objects must implement the collectionView:numberOfItemsInSection: and collectionView:cellForItemAtIndexPath: methods. Requir...

iOS • UICollectionView

Inter-operating with Java reflection

To obtain a Java's Class object from Kotlin's KClass use the .java extension property: val stringKClass: KClass<String> = String::class val c1: Class<String> = stringKClass.java val c2: Class<MyClass> = MyClass::class.java The latter example will be optimized by the compile...

Kotlin • Reflection

The new Qt5 connection syntax

The conventional connect syntax that uses SIGNAL and SLOT macros works entirely at runtime, which has two drawbacks: it has some runtime overhead (resulting also in binary size overhead), and there's no compile-time correctness checking. The new syntax addresses both issues. Before checking the synt...

Qt • Signals and Slots

Netwide Assembler - NASM

NASM is by far the most ported assembler for the x86 architecture - it's available for practically every Operating System based on the x86 (even being included with MacOS), and is available as a cross-platform assembler on other platforms. This assembler uses Intel syntax, but it is different from ...

Intel x86 Assembly Language & Microarchitecture • Assemblers

Safe downcasting

Suppose that you have a pointer to an object of a polymorphic class: Shape *ps; // see example on defining a polymorphic class ps = get_a_new_random_shape(); // if you don't have such a function yet, you // could just write ps = new Square...

C++ • Polymorphism

Displaying numbers with required precision

var a:Number=0.123456789; trace(a); // 0.123456789 trace(a.toPrecision(4)); // 0.1235 trace(a.toFixed(4)); // 0.1235 trace(a.toExponential(4)); // 1.2345e-1 trace(a.toString(16)); // 0 - works for integer part only var b:Number=12345678.9876543; // a bigg...

ActionScript 3 • Working with numerical values

How to create resuable component using directive

AngularJS directives are what controls the rendering of the HTML inside an AngularJS application. They can be an Html element, attribute, class or a comment. Directives are used to manipulate the DOM, attaching new behavior to HTML elements, data binding and many more. Some of examples of directives...

AngularJS • Custom Directives

Add column with default value

The following example adds a column admin to the users table, and gives that column the default value false. class AddDetailsToUsers < ActiveRecord::Migration[5.0] def change add_column :users, :admin, :boolean, default: false end end Migrations with defaults might take a long tim...

Ruby on Rails • ActiveRecord Migrations

ngShow

AngularJS code for dynamically showing/hiding an element: <p ng-show="SomeScopeProperty">This is conditionally shown.</p> KnockoutJS equivalent: <p data-bind="visible: SomeScopeObservable">This is conditionally shown.</p>

knockout.js • Equivalents of AngularJS bindings

A very simple Hello World application

Starting from a fresh installation of Codeigniter 3, here is a simple way to start with an Hello World application, to break the ice with this solid PHP framework. To do this you can start creating the view that we want to be shown for our Hello World app. We are going to put it in your applicatio...

codeigniter • Let's start: Hello World