Tutorial by Examples: w

Embedded Lua Interpreter with Custom API and Lua Customization

Demonstrate how to embed a lua interpreter in C code, expose a C-defined function to Lua script, evaluate a Lua script, call a C-defined function from Lua, and call a Lua-defined function from C (the host). In this example, we want the mood to be set by a Lua script. Here is mood.lua: -- Get versi...

Lua • Introduction to Lua C API

Setting up a WebRTC-based communication system

To setup a WebRTC-based communication system, you need three main components: A WebRTC signaling server To establish a WebRTC connections, peers need to contact a signaling server, which then provides the address information the peers require to set up a peer-to-peer connection. Signaling serv...

webrtc • Getting started with webrtc

Model Validation with Validation Attrributes

Validation attributes can be used to easily configure model validation. public class MyModel { public int id { get; set; } //sets the FirstName to be required, and no longer than 100 characters [Required] [StringLength(100)] public string FirstName { get; set; } } Th...

asp.net-core • Models

How to add a UIImage to a CALayer

You can add an image to a view's layer simply by using its contents property: myView.layer.contents = UIImage(named: "star")?.CGImage Note that the UIImage needs to be converted to a CGImage. If you wish to add the image in its own layer, you can do it like this: let myLayer = CA...

iOS • CALayer

Updating Auto Layout with Trait Collection Changes

Making an app adaptive – that is, responding to size class changes by changing your layout – often involves lots of help from the Auto Layout system. One of the primary ways apps become adaptive is by updating the active Auto Layout constraints when a view's size class changes. For example, conside...

iOS • Size Classes and Adaptivity

Custom Alert Dialog with EditText

void alertDialogDemo() { // get alert_dialog.xml view LayoutInflater li = LayoutInflater.from(getApplicationContext()); View promptsView = li.inflate(R.layout.alert_dialog, null); AlertDialog.Builder alertDialogBuilder = new AlertDialog.Builder( ...

Android • Dialog

How do foldFree and iterM work?

There are some functions to help tear down Free computations by interpreting them into another monad m: iterM :: (Functor f, Monad m) => (f (m a) -> m a) -> (Free f a -> m a) and foldFree :: Monad m => (forall x. f x -> m x) -> (Free f a -> m a). What are they doing? First l...

Haskell Language • Free Monads

A simple authentication POST request with Jsoup

A simple POST request with authentication data is demonstrated below, note that the username and password field will vary depending on the website: final String USER_AGENT = "Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/51.0.2704.103 Safari/537.36"; ...

Jsoup • Logging into websites with Jsoup

A more comprehensive authentication POST request with Jsoup

Most websites require a much more complicated process than the one demonstrated above. Common steps for logging into a website are: Get the unique cookie from the initial login form. Inspect the login form to see what the destination url is for the authentication request Parse the login form t...

Jsoup • Logging into websites with Jsoup

Parsing JavaScript Generated Page with Jsoup and HtmUnit

page.html - source code <html> <head> <script src="loadData.js"></script> </head> <body onLoad="loadData()"> <div class="container"> <table id="data" border="1"> <...

Jsoup • Parsing Javascript Generated Pages

Splitting with IFS

To be more clear, let's create a script named showarg: #!/usr/bin/env bash printf "%d args:" $# printf " <%s>" "$@" echo Now let's see the differences: $ var="This is an example" $ showarg $var 4 args: <This> <is> <an> <exa...

Bash • Word splitting

Using uWSGI to run a flask application

The built-in werkzeug server certainly is not suitable for running production servers. The most obvious reason is the fact that the werkzeug server is single-threaded and thus can only handle one request at a time. Because of this we want to use the uWSGI Server to serve our application instead. In...

Flask • Deploying Flask application using uWSGI web server with Nginx

Installing nginx and setting it up for uWSGI

Now we want to install nginx to serve our application. sudo apt-get install nginx # on debian/ubuntu Then we create a configuration for our website cd /etc/nginx/site-available # go to the configuration for available sites # create a file flaskconfig with your favourite editor flaskconfig...

Flask • Deploying Flask application using uWSGI web server with Nginx

Reads file (/etc/passwd) line by line and field by field

#!/bin/bash FILENAME="/etc/passwd" while IFS=: read -r username password userid groupid comment homedir cmdshell do echo "$username, $userid, $comment $homedir" done < $FILENAME In unix password file, user information is stored line by line, each line consisting of i...

Bash • Read a file (data stream, variable) line-by-line (and/or field-by-field)?

How to compose values and functions using common operators

In Object Oriented Programming a common task is to compose objects (values). In Functional Programming it is as common task to compose values as well as functions. We are used to compose values from our experience of other programming languages using operators like +, -, *, / and so on. Value co...

F# • Operators

Adding a UIRefreshControl to a TableView

Assumptions: TableView - reference to the TableView DataSource - is a class which inherits UITableViewSource DataSource.Objects - is a public List< object >(), accessible to the UIViewController private UIRefreshControl refreshControl; public override void ViewDidLoad() { base.V...

Xamarin.iOS • Adding UIRefreshControl to a table view

RecordWildCards

See RecordWildCards

Haskell Language • Common GHC Language Extensions

POSIX Timer with SIGEV_THREAD notification

This example demonstrates POSIX Timer usage with CLOCK_REALTIME clock and SIGEV_THREAD notification method. #include <stdio.h> /* for puts() */ #include <string.h> /* for memset() */ #include <unistd.h> /* for sleep() */ #include <stdlib.h> /* for EXIT_SUCCESS */ #inc...

POSIX • Timers

Waiting For Ajax Requests to Complete

C# using OpenQA.Selenium using OpenQA.Selenium.Chrome; using System.Threading; namespace WebDriver Tests { class WebDriverWaits { static void Main() { IWebDriver driver = new ChromeDriver(@"C:\WebDriver"); driver.Na...

selenium-webdriver • Wait

Detecting when UIScrollView finished scrolling with delegate methods

scrollViewDidEndDecelerating: this tells the delegate that the scroll view has ended decelerating the scrolling movement. Objective C: - (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView { [self stoppedScrolling]; } - (void)scrollViewDidEndDragging:(UIScrollView *)scrollView w...

iOS • UIScrollView