Tutorial by Examples | RIP Tutorial

Use git send-email with Gmail

Background: if you work on a project like the Linux kernel, rather than make a pull request you will need to submit your commits to a listserv for review. This entry details how to use git-send email with Gmail. Add the following to your .gitconfig file: [sendemail] smtpserver = smtp.googlema...

Git • git send-email

When to use a Static variable

A Static variable declared locally is not destructed and does not lose its value when the Sub procedure is exited. Subsequent calls to the procedure do not require re-initialization or assignment although you may want to 'zero' any remembered value(s). These are particularly useful when late bindin...

VBA • Declaring Variables

Infinite Streams via Recursion

Streams can be built that reference themselves and thus become infinitely recursive. // factorial val fact: Stream[BigInt] = 1 #:: fact.zipWithIndex.map{case (p,x)=>p*(x+1)} fact.take(10) // (1, 1, 2, 6, 24, 120, 720, 5040, 40320, 362880) fact(24) // 620448401733239439360000 // the ...

Scala Language • Streams

List files and folders

To list files and folders inside current directory, we use ls command: user@host:/$ ls bin boot cdrom dev etc home initrd.img lib lib64 lost+found media mnt opt proc root run sbin srv sys tmp usr var vmlinuz ls prints folder structure in simple view, color coded by type....

Ubuntu • Basic Terminal commands

Animate at a specified interval (add a new rectangle every 1 second)

This example adds a new rectangle to the canvas every 1 second (== a 1 second interval) Annotated Code: <!doctype html> <html> <head> <style> body{ background-color:white; } #canvas{border:1px solid red; } </style> <script> window.onload=(functio...

html5-canvas • Animation

Animate at a specified time (an animated clock)

This example animates a clock showing the seconds as a filled wedge Annotated Code: <!doctype html> <html> <head> <style> body{ background-color:white; } #canvas{border:1px solid red; } </style> <script> window.onload=(function(){ // canva...

html5-canvas • Animation

Use requestAnimationFrame() NOT setInterval() for animation loops

requestAnimationFrame is similar to setInterval, it but has these important improvements: The animation code is synchronized with display refreshes for efficiency The clear + redraw code is scheduled, but not immediately executed. The browser will execute the clear + redraw code only when the d...

html5-canvas • Animation

Animate an image across the Canvas

This example loads and animates and image across the Canvas Important Hint! Make sure you give your image time to fully load by using image.onload. Annotated Code <!doctype html> <html> <head> <style> body{ background-color:white; } #canvas{border:1px solid re...

html5-canvas • Animation

Don't draw animations in your event handlers (a simple sketch app)

During mousemove you get flooded with 30 mouse events per second. You might not be able to redraw your drawings at 30 times per second. Even if you can, you're probably wasting computing power by drawing when the browser is not ready to draw (wasted == across display refresh cycles). Therefore it m...

html5-canvas • Animation

Download

A distribution can be downloaded from the Apache Struts website. The full distribution contains: the struts2-core.jar file related dependencies example applications a copy of the documentation in HTML format the complete source code. Blank Application The blank web application in the dis...

struts2 • Getting started with struts2

Runtime Code Generation

<#@ template language="C#" #> //Language of your project <#@ assembly name="System.Core" #> <#@ import namespace="System.Linq" #> <#@ import namespace="System.Text" #> <#@ import namespace="System.Collections.Generic" ...

C# Language • T4 Code Generation

UIColor from an image pattern

You can create a UIColor object using an image pattern by using the UIColor(patternImage:_) method. btn.backgroundColor = UIColor(patternImage: UIImage(named: "image")!)

iOS • UIColor

Working with Varargs parameters

Using varargs as a parameter for a method definition, it is possible to pass either an array or a sequence of arguments. If a sequence of arguments are passed, they are converted into an array automatically. This example shows both an array and a sequence of arguments being passed into the printVar...

Java Language • Varargs (Variable Argument)

Using the Graphics class

Intro The Graphics class allows you to draw onto java components such as a Jpanel, it can be used to draw strings, lines, shapes and images. This is done by overriding the paintComponent(Graphics g) method of the JComponent you are drawing on using the Graphics object received as argument to do the...

swing • Graphics

Drawing images

Images can be drawn onto a JComponent using the drawImage method of class Graphics: loading an image BufferedImage img; try { img = ImageIO.read(new File("stackoverflow.jpg")); } catch (IOException e) { throw new RuntimeException("Could not load image", e); } dr...

swing • Graphics

Even and Odd Numbers

The even? method can be used to determine if a number is even 4.even? # => true 5.even? # => false The odd? method can be used to determine if a number is odd 4.odd? # => false 5.odd? # => true

Ruby Language • Numbers

Rounding Numbers

The round method will round a number up if the first digit after its decimal place is 5 or higher and round down if that digit is 4 or lower. This takes in an optional argument for the precision you're looking for. 4.89.round # => 5 4.25.round # => 4 3.141526.round(1) # => ...

Ruby Language • Numbers

Restrict Number to Min/Max Range

If you need to clamp a number to keep it inside a specific range boundary function clamp(min, max, val) { return Math.min(Math.max(min, +val), max); } console.log(clamp(-10, 10, "4.30")); // 4.3 console.log(clamp(-10, 10, -8)); // -8 console.log(clamp(-10, 10, 12)); // ...

JavaScript • Arithmetic (Math)

Installation or Setup

Detailed instructions on getting netty set up or installed.

netty • Getting started with netty

Dialects of Lisp and their implementations

Invented by John McCarthy around 1958, Lisp (List Processor) has continued to grow into an entire family of languages. Since StackOverflow is more about practical programming problems, typically problems will involve actual Lisp dialects or derived languages and their implementations. Problems that...

lisp • Getting started with lisp