Tutorial by Examples: u

Computed Properties

Different from stored properties, computed properties are built with a getter and a setter, performing necessary code when accessed and set. Computed properties must define a type: var pi = 3.14 class Circle { var radius = 0.0 var circumference: Double { get { ret...

Print environment information before build

The following is handy to have in build logs that identifies the build machine, and some parameters; simply make you main task depend on this task to print it before every build. <!-- Print Environment Info --> <target name="environment"> <!-- Get the current ti...

Operations that return NaN

Mathematical operations on values other than numbers return NaN. "a" + 1 "b" * 3 "cde" - "e" [1, 2, 3] * 2 An exception: Single-number arrays. [2] * [3] // Returns 6 Also, remember that the + operator concatenates strings. "a" + "b&...

Math library functions that return NaN

Generally, Math functions that are given non-numeric arguments will return NaN. Math.floor("a") The square root of a negative number returns NaN, because Math.sqrt does not support imaginary or complex numbers. Math.sqrt(-1)

Testing for NaN using isNaN()

window.isNaN() The global function isNaN() can be used to check if a certain value or expression evaluates to NaN. This function (in short) first checks if the value is a number, if not tries to convert it (*), and then checks if the resulting value is NaN. For this reason, this testing method may ...

Basic usage getting content between buffers and clearing

Output buffering allows you to store any textual content (Text, HTML) in a variable and send to the browser as one piece at the end of your script. By default, php sends your content as it interprets it. <?php // Turn on output buffering ob_start(); // Print some output to the buffer (via...

Nested output buffers

You can nest output buffers and fetch the level for them to provide different content using the ob_get_level() function. <?php $i = 1; $output = null; while( $i <= 5 ) { // Each loop, creates a new output buffering `level` ob_start(); print "Current nest level: &quo...

Capturing the output buffer to re-use later

In this example, we have an array containing some data. We capture the output buffer in $items_li_html and use it twice in the page. <?php // Start capturing the output ob_start(); $items = ['Home', 'Blog', 'FAQ', 'Contact']; foreach($items as $item): // Note we're about to step &q...

Running output buffer before any content

ob_start(); $user_count = 0; foreach( $users as $user ) { if( $user['access'] != 7 ) { continue; } ?> <li class="users user-<?php echo $user['id']; ?>"> <a href="<?php echo $user['link']; ?>"> <?php echo $user...

Using Output buffer to store contents in a file, useful for reports, invoices etc

<?php ob_start(); ?> <html> <head> <title>Example invoice</title> </head> <body> <h1>Invoice #0000</h1> <h2>Cost: £15,000</h2> ... </body> </html> <?php...

Using the multiprocessing module to parallelise tasks

import multiprocessing def fib(n): """computing the Fibonacci in an inefficient way was chosen to slow down the CPU.""" if n <= 2: return 1 else: return fib(n-1)+fib(n-2) p = multiprocessing.Pool() print(p.map(fib,[38,37,3...

Basics of multithreading

Using the threading module, a new thread of execution may be started by creating a new threading.Thread and assigning it a function to execute: import threading def foo(): print "Hello threading!" my_thread = threading.Thread(target=foo) The target parameter references the fun...

Quoting

By adding > in front of a line, you can create quoted text! > I am a quote I am a quote!

Introduction to WordPress

WordPress [WP] is an open source Content Management System for building apps, websites, and blogs. WP is written in PHP and uses MySQL as the data store for the user content and configuration. It has a rich ecosystem of plugins and themes and enjoys a vibrant open source community, good documentatio...

Loading and using a module

A module can be "imported", or otherwise "required" by the require() function. For example, to load the http module that ships with Node.js, the following can be used: const http = require('http'); Aside from modules that are shipped with the runtime, you can also require mod...

Creating a hello-world.js module

Node provides the module.exports interface to expose functions and variables to other files. The most simple way to do so is to export only one object (function or variable), as shown in the first example. hello-world.js module.exports = function(subject) { console.log('Hello ' + subject); }...

Strikethrough

To create strike-through text, surround the text with ~~double tildes~~. Note: on StackExchange this formatting isn't included. Instead use the html tag <s>text</s>. (In chat you can use ---three hyphens---.)

General Pattern that does most commonly asked about tasks

The following is how to properly use the java.util.Scanner class to interactively read user input from System.in correctly( sometimes referred to as stdin, especially in C, C++ and other languages as well as in Unix and Linux). It idiomatically demonstrates the most common things that are requested ...

Getting the First Page in Ruby

This Ruby example uses Mechanize, a library to automate web interactions. client_id is an OAuth client_id. game is the game directory to list. require 'mechanize' master_agent = Mechanize.new client_id = "123" game = "Minecraft" url = "https://api.twitch.tv/kraken...

Numbered lists

1. Lists 2. Can be 3. Numbered Lists Can be Numbered Note that the numbers themselves are ignored: 1. This is the first item 5. This is the fifth item 7. This is the seventh item This is the first item This is the fifth item This is the seventh item However, the firs...

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