Tutorial by Examples: co

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

Content Scripts

A content script is extension code that runs alongside a normal page. They have full access to the web page's DOM (and are, in fact, the only part of the extension that can access a page's DOM), but the JavaScript code is isolated, a concept called Isolated World. Each extension has its own content...

google-chrome-extension • Getting started with google-chrome-extension

Loop Control statements : Break and Continue

Loop control statements are used to change the flow of execution from its normal sequence. When execution leaves a scope, all automatic objects that were created in that scope are destroyed. The break and continue are loop control statements. The break statement terminates a loop without any furthe...

C++ • Loops

Override merge/compare tools

Got to Tools | Options | Source Control | Visual Studio Team Foundation Server click on the Configure User Tools: You can add separate overrides for 'Compare' and 'Merge' operations. Click on Add and select the operation you want to override. You'd need to type the path to the tool you use, and ...

Visual Studio • Visual Studio tools

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

Leaked variables in list comprehension

Python 2.x2.3 x = 'hello world!' vowels = [x for x in 'AEIOU'] print (vowels) # Out: ['A', 'E', 'I', 'O', 'U'] print(x) # Out: 'U' Python 3.x3.0 x = 'hello world!' vowels = [x for x in 'AEIOU'] print (vowels) # Out: ['A', 'E', 'I', 'O', 'U'] print(x) # Out: 'hello world!' ...

Python Language • Incompatibilities moving from Python 2 to Python 3

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

Let's use the controller a little more

Now we'll try going for a little more complex example, using the capabilities of the controller to fill in the view. Here is our view: /application/views/hello_world.php <!DOCTYPE html> <html lang="en"> <head> <meta charset="utf-8"> <titl...

codeigniter • Let's start: Hello World

Using collection initializer inside object initializer

public class Tag { public IList<string> Synonyms { get; set; } } Synonyms is a collection-type property. When the Tag object is created using object initializer syntax, Synonyms can also be initialized with collection initializer syntax: Tag t = new Tag { Synonyms = new List&...

C# Language • Collection Initializers

Read All Contents of a File

To read the contents to a file into a string variable: Dim fileContents As String = System.IO.File.ReadAllText("filename.txt") ReadAllText will open the specified file, read data to the end, then close the file. To read a file, separating it into an array element for each line: Dim f...

Visual Basic .NET Language • File Handling

?. (Null Conditional Operator)

6.0 Introduced in C# 6.0, the Null Conditional Operator ?. will immediately return null if the expression on its left-hand side evaluates to null, instead of throwing a NullReferenceException. If its left-hand side evaluates to a non-null value, it is treated just like a normal . operator. Note tha...

C# Language • Operators

Connecting to the local Wildfly server

To connect to a local Wildfly server via the command line, the tool bin/jboss-cli.sh can be used: $ ./bin/jboss-cli.sh --connect [standalone@localhost:9990 /] To connect to a remote Wildfly server, use the --controller option: $ ./bin/jboss-cli.sh --connect --controller=localhost:9990 [stan...

wildfly • Command line interface (CLI)

Recording audio from a microphone source

In order to record audio from a user's microphone, we must first gain permission from the user to access the device: navigator.mediaDevices.getUserMedia({ audio: true }) .then(successCallback) .catch(failureCallback); On success, our successCallback will be called with a MediaStream ob...

web-audio • Getting started with web-audio

End of Line Comment

Everything to the right of // in the same line is commented. int i = 0; // Commented out text

dart • Comments

A simple control: rating

Let us build a simple control, a rating widget, intended to be used as: <rating min="0" max="5" nullifier="true" ng-model="data.rating"></rating> No fancy CSS for now; this would render as: 0 1 2 3 4 5 x Clicking on a number selects that ra...

AngularJS • Directives using ngModelController

Converting Scala Collections to Java Collections and vice versa

When you need to pass a collection into a Java method: import scala.collection.JavaConverters._ val scalaList = List(1, 2, 3) JavaLibrary.process(scalaList.asJava) If the Java code returns a Java collection, you can turn it into a Scala collection in a similar manner: import scala.collectio...

Scala Language • Java Interoperability

Creating Minification-Safe Angular Controllers

To create minification-safe angular controllers, you will change the controller function parameters. The second argument in the module.controller function should be passed an array, where the last parameter is the controller function, and every parameter before that is the name of each injected val...

AngularJS • Controllers

Ignore files locally without committing ignore rules

.gitignore ignores files locally, but it is intended to be committed to the repository and shared with other contributors and users. You can set a global .gitignore, but then all your repositories would share those settings. If you want to ignore certain files in a repository locally and not make t...

Git • Ignoring Files and Folders

Garbage collector - the __gc metamethod

5.2 Objects in lua are garbage collected. Sometimes, you need to free some resource, want to print a message or do something else when an object is destroyed (collected). For this, you can use the __gc metamethod, which gets called with the object as argument when the object is destroyed. You could...

Lua • Metatables

Setting up background configuration

To create a background session // Swift: let mySessionID = "com.example.bgSession" let bgSessionConfig = NSURLSessionConfiguration.backgroundSessionConfigurationWithIdentifier(mySessionID) let session = NSURLSession(configuration: bgSessionConfig) // add tasks here //...

iOS • NSURLSession