Tutorial by Examples: x

Complex numbers and the cmath module

The cmath module is similar to the math module, but defines functions appropriately for the complex plane. First of all, complex numbers are a numeric type that is part of the Python language itself rather than being provided by a library class. Thus we don't need to import cmath for ordinary arith...

Python Language • Math Module

Disabling inline expansion

Inline expansion can be disabled with the go:noinline pragma. For example, if we build the following simple program: package main func printhello() { println("Hello") } func main() { printhello() } we get output that looks like this (trimmed for readability): $ go ...

Go • Inline Expansion

Debugging with IEX.pry/0

Debugging with IEx.pry/0 is quite simple. require IEx in your module Find the line of code you want to inspect Add IEx.pry after the line Now start your project (e.g. iex -S mix). When the line with IEx.pry/0 is reached the program will stop and you have the chance to inspect. It is like a ...

Elixir Language • Debugging Tips

Spawning a shell to execute a command

To run a command in a shell, in which you required buffered output (i.e. it is not a stream), use child_process.exec. For example, if you wanted to run the command cat *.js file | wc -l, with no options, that would look like this: const exec = require('child_process').exec; exec('cat *.js file | w...

Node.js • Executing files or commands with Child Processes

Spawning a process to run an executable

If you are looking to run a file, such as an executable, use child_process.execFile. Instead of spawning a shell like child_process.exec would, it will directly create a new process, which is slightly more efficient than running a command. The function can be used like so: const execFile = require(...

Node.js • Executing files or commands with Child Processes

Testing Exceptions

Programs throw errors when for instance wrong input is given. Because of this, one needs to make sure that an error is thrown when actual wrong input is given. Because of that we need to check for an exact exception, for this example we will use the following exception: class WrongInputException(Ex...

Python Language • Unit Testing

Extended project definition

Some of the additional attributes are parsed by the npm website like repository, bugs or homepage and shown in the infobox for this packages { "main": "server.js", "repository" : { "type": "git", "url": "git+https:/...

Node.js • package.json

Repeat an action x times

repeat(10) { i -> println("This line will be printed 10 times") println("We are on the ${i + 1}. loop iteration") }

Kotlin • Loops in Kotlin

Example showcasing the basic concepts

The following example is an introduction to: Template compilation using underscore Accessing variables in a template Creating a view Rendering a view Showing a view <html> <head> <script src="https://code.jquery.com/jquery-3.1.0.min.js"></script> ...

backbone.js • Getting started with backbone.js

Dispose system resources even when an exception is raised

Higher-order functions can be used to ensure that system resources are disposed, even when a treatment raises an exception. The pattern used by with_output_file allows a clean separation of concerns: the higher-order with_output_file functions takes care of managing the system resources bound to fi...

OCaml • Higher Order Functions

Using global external libraries without typings

Although modules are ideal, if the library you are using is referenced by a global variable (like $ or _), because it was loaded by a script tag, you can create an ambient declaration in order to refer to it: declare const _: any;

TypeScript • Importing external libraries

role="checkbox"

A checkable input that has three possible values: true, false, or mixed. <p> <input type="checkbox" role="checkbox" aria-checked="false"> I agree to the terms </p>

HTML • ARIA

role="combobox"

A presentation of a select; usually similar to a textbox where users can type ahead to select an option, or type to enter arbitrary text as a new item in the list. <input type="text" role="combobox" aria-expanded="false"> Typically, you would use JavaScript to...

HTML • ARIA

role="listbox"

A widget that allows the user to select one or more items from a list of choices. <ul role="listbox"> <li>One</li> <li>Two</li> <li>Three</li> </ul> Typically, you would use JavaScript to build the multiple-selection functionali...

HTML • ARIA

role="menuitemcheckbox"

A checkable menuitem that has three possible values: true, false, or mixed. <ul role="menu"> <li role="menuitem">Console</li> <li role="menuitem">Layout</li> <li role="menuitemcheckbox" aria-checked="true"&g...

HTML • ARIA

role="searchbox"

A type of textbox intended for specifying search criteria. <div role="search"> <input role="searchbox" type="text"> <button role="button">Search</button> </div>

HTML • ARIA

role="textbox"

Input that allows free-form text as its value. <textarea role="textbox"></textarea>

HTML • ARIA

Reading text from a file encoded in UTF-8

import java.io.BufferedReader; import java.io.BufferedWriter; import java.io.IOException; import java.nio.charset.StandardCharsets; import java.nio.file.Files; import java.nio.file.Paths; public class ReadingUTF8TextFile { public static void main(String[] args) throws IOException { ...

Java Language • Character encoding

Writing text to a file in UTF-8

import java.io.BufferedWriter; import java.io.IOException; import java.nio.charset.StandardCharsets; import java.nio.file.Files; import java.nio.file.Paths; public class WritingUTF8TextFile { public static void main(String[] args) throws IOException { //StandardCharsets is avail...

Java Language • Character encoding

Joining Examples

Query to create table on db CREATE TABLE `user` ( `id` smallint(5) unsigned NOT NULL AUTO_INCREMENT, `name` varchar(30) NOT NULL, `course` smallint(5) unsigned DEFAULT NULL, PRIMARY KEY (`id`) ) ENGINE=InnoDB; CREATE TABLE `course` ( `id` smallint(5) unsigned NOT NULL AUTO_INCREMENT, `nam...

MySQL • Joins