Tutorial by Examples: s

Property Observers

Property observers respond to changes to a property's value. var myProperty = 5 { willSet { print("Will set to \(newValue). It was previously \(myProperty)") } didSet { print("Did set to \(myProperty). It was previously \(oldValue)") } } m...

Swift Language • Variables & Properties

JavaScript

Content has been moved back to good 'ol JSP wiki page

jsp • Getting started with jsp

Subscript/Superscript

x<sub>2</sub> produces x2 x<sup>2</sup> produces x2

Markdown • Text Formatting

Basic Responsive Application

package { import flash.display.Sprite; import flash.display.StageAlign; import flash.display.StageScaleMode; import flash.events.Event; public class Main extends Sprite { //Document Class Main Constructor public function Main() { ...

ActionScript 3 • Responsive Application Design

Compare NSURL

NSString *urlString = @"https://www.stackoverflow.com"; NSURL *myUrl = [NSURL URLWithString: urlString]; NSURL *myUrl2 = [NSURL URLWithString: urlString]; if ([myUrl isEqual:myUrl2]) return YES;

Objective-C Language • NSURL

Installation

Express JS is the goto framework for developing Web Applications, APIs and almost any kind of Backend using Node. To install express, all you have to do is run the npm command npm install express --save And you're done. To create and run a new express server create a file app.js and add this ...

express • Getting started with express

Using IBInspectable and IBDesignable

One (or two) of the coolest new features in recent Xcode releases are the IBInspectable properties and IBDesignable UIViews. These have nothing to do with the functionality of your application but instead impact the developer experience in Xcode. The goal is to be able to visually inspect custom v...

iOS • UIView

Installation or Setup

Detailed instructions on getting mapbox set up or installed.

mapbox • Getting started with mapbox

Iterating Over a Hash

A Hash includes the Enumerable module, which provides several iteration methods, such as: Enumerable#each, Enumerable#each_pair, Enumerable#each_key, and Enumerable#each_value. .each and .each_pair iterate over each key-value pair: h = { "first_name" => "John", "last_na...

Ruby Language • Hashes

Selecting with table alias

SELECT e.Fname, e.LName FROM Employees e The Employees table is given the alias 'e' directly after the table name. This helps remove ambiguity in scenarios where multiple tables have the same field name and you need to be specific as to which table you want to return data from. SELECT e.Fname,...

SQL • SELECT

Use the `email` as username and get rid of the `username` field

If you want to get rid of the username field and use email as unique user identifier, you will have to create a custom User model extending AbstractBaseUser instead of AbstractUser. Indeed, username and email are defined in AbstractUser and you can't override them. This means you will also have to r...

Django • Extending or Substituting User Model

Basic Setup

Backbone requires Underscore and (optionally) jQuery - for DOM manipulation (using Backbone.View) and RESTful persistence. The quickest way to get up and running with Backbone is to create an index.html file with simple script tags in the HTML <head>: <html> <head> ...

backbone.js • Getting started with backbone.js

Parsing dates when reading from csv

You can specify a column that contains dates so pandas would automatically parse them when reading from the csv pandas.read_csv('data_file.csv', parse_dates=['date_column'])

pandas • Pandas IO tools (reading and saving data sets)

Example usage

Read text file from path: val sc: org.apache.spark.SparkContext = ??? sc.textFile(path="/path/to/input/file") Read files using wildcards: sc.textFile(path="/path/to/*/*") Read files specifying minimum number of partitions: sc.textFile(path="/path/to/input/file&qu...

apache-spark • Text files and operations in Scala

Recursive functions

A recursive function is a function that calls itself in its definition. For example the mathematical function, factorial, defined by factorial(n) = n*(n-1)*(n-2)*...*3*2*1. can be programmed as def factorial(n): #n here should be an integer if n == 0: return 1 else: ...

Python Language • Functions

sealed

When applied to a class, the sealed modifier prevents other classes from inheriting from it. class A { } sealed class B : A { } class C : B { } //error : Cannot derive from the sealed class When applied to a virtual method (or virtual property), the sealed modifier prevents this method (proper...

C# Language • Keywords

sizeof

Used to obtain the size in bytes for an unmanaged type int byteSize = sizeof(byte) // 1 int sbyteSize = sizeof(sbyte) // 1 int shortSize = sizeof(short) // 2 int ushortSize = sizeof(ushort) // 2 int intSize = sizeof(int) // 4 int uintSize = sizeof(uint) // 4 int longSize = sizeof(long) // 8 ...

C# Language • Keywords

static

The static modifier is used to declare a static member, which does not need to be instantiated in order to be accessed, but instead is accessed simply through its name, i.e. DateTime.Now. static can be used with classes, fields, methods, properties, operators, events, and constructors. While an in...

C# Language • Keywords

Binary operators with assignment

C# has several operators that can be combined with an = sign to evaluate the result of the operator and then assign the result to the original variable. Example: x += y is the same as x = x + y Assignment operators: += -= *= /= %= &= |= ^= <<= >>=

C# Language • Operators

Array comparison

For simple array comparison you can use JSON stringify and compare the output strings: JSON.stringify(array1) === JSON.stringify(array2) Note: that this will only work if both objects are JSON serializable and do not contain cyclic references. It may throw TypeError: Converting circular struct...

JavaScript • Arrays