Tutorial by Examples: nd

A context manager is an object that is notified when a context (a block of code) starts and ends. You commonly use one with the with statement. It takes care of the notifying. For example, file objects are context managers. When a context ends, the file object is closed automatically: open_file = ...

Windows Environment Install XAMPP or WAMP Download and Unzip the package from Codeigniter.com Extract all the document in the server space (htdocs or www directory) Mac Environment Install MAMP Download and Unzip the package from Codeigniter.com Extract all the document in the server sp...

Running the latest Liferay CE is straightforward: Go to https://www.liferay.com/downloads. Choose a bundle among the ones listed. For beginners, the Tomcat bundle is a good choice. Click in "Download." Unzip the download package whenever you find fit. The unzipped directory will...

With promises: function doTheThing() { return doOneThing() .then(doAnother) .then(doSomeMore) .catch(handleErrors) } With async functions: async function doTheThing() { try { const one = await doOneThing(); const another = await doAnother(...

Requirements: Protractor requires the following dependencies to be installed prior to installation: Java JDK 1.7 or higher Node.js v4 or higher Installation: Download and install Node.js from this URL: https://nodejs.org/en/ To see if the Node.js installation is successfull, you can go an...

Use the begin/rescue block to catch (rescue) an exception and handle it: begin # an execution that may fail rescue # something to execute in case of failure end A rescue clause is analogous to a catch block in a curly brace language like C# or Java. A bare rescue like this rescues Stand...

You can handle multiple errors in the same rescue declaration: begin # an execution that may fail rescue FirstError, SecondError => e # do something if a FirstError or SecondError occurs end You can also add multiple rescue declarations: begin # an execution that may fail rescue ...

Swift label.backgroundColor = UIColor.redColor() label.backgroundColor = .redColor() Swift 3 label.backgroundColor = UIColor.red Objective-C label.backgroundColor = [UIColor redColor];

CSS div{ width: 150px; height:150px; background-color: red; transition: background-color 1s; } div:hover{ background-color: green; } HTML <div></div> This example will change the background color when the div is hovered the background-color change will...

Directives are one of the most powerful features of angularjs. Custom angularjs directives are used to extend functionality of html by creating new html elements or custom attributes to provide certain behavior to an html tag. directive.js // Create the App module if you haven't created it yet va...

Download and install Visual Studio. Visual Studio can be downloaded from VisualStudio.com. The Community edition is suggested, first because it is free, and second because it involves all the general features and can be extended further. Open Visual Studio. Welcome. Go to File → New ...

Breaking out of the loop and continuing to the next iteration is also supported in Go, like in many other languages: for x := 0; x < 10; x++ { // loop through 0 to 9 if x < 3 { // skips all the numbers before 3 continue } if x > 5 { // breaks out of the loop once x...

Govendor is a tool that is used to import 3rd party packages into your code repository in a way that is compatible with golang's vendoring. Say for example that you are using a 3rd party package bosun.org/slog: package main import "bosun.org/slog" func main() { slog.Infof(&quo...

In Python you can define a series of conditionals using if for the first one, elif for the rest, up until the final (optional) else for anything not caught by the other conditionals. number = 5 if number > 2: print("Number is bigger than 2.") elif number < 2: # Optional cl...

The ternary operator is used for inline conditional expressions. It is best used in simple, concise operations that are easily read. The order of the arguments is different from many other languages (such as C, Ruby, Java, etc.), which may lead to bugs when people unfamiliar with Python's "s...

Basic usage: PropertyInfo prop = myInstance.GetType().GetProperty("myProperty"); // get the value myInstance.myProperty object value = prop.GetValue(myInstance); int newValue = 1; // set the value myInstance.myProperty to newValue prop.setValue(myInstance, newValue); Setting rea...

This example use the default boxplot() function and the irisdata frame. > head(iris) Sepal.Length Sepal.Width Petal.Length Petal.Width Species 1 5.1 3.5 1.4 0.2 setosa 2 4.9 3.0 1.4 0.2 setosa 3 4.7 3.2 ...

Using the Reflection API, it is possible to change or get the value of a field at runtime. For example, you could use it in an API to retrieve different fields based on a factor, like the OS. You can also remove modifiers like final to allow modifing fields that are final. To do so, you will need t...

When defining discriminated unions you can name elements of tuple types and use these names during pattern matching. type Shape = | Circle of diameter:int | Rectangle of width:int * height:int let shapeIsTenWide = function | Circle(diameter=10) | Rectangle(width=10) -> t...

To use Vagrant on Windows platform you need to install virtualization software and an ssh command-line tool first. This example will use freeware VirtualBox and Cygwin. Install VirtualBox Download the latest VirtualBox version from the official download page and run the downloaded file. Note that ...