Tutorial by Examples: b

Variable Names

Variables hold data. Name them after what they're used for, not after their data type or scope, using a noun. If you feel compelled to number your variables (e.g. thing1, thing2, thing3), then consider using an appropriate data structure instead (e.g. an array, a Collection, or a Dictionary). Names...

VBA • Naming Conventions

Basic Component

Given the following HTML file: index.html <!DOCTYPE html> <html> <head> <meta charset="utf-8" /> <title>React Tutorial</title> <script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.2.1/react.js"></script>...

React • Components

Benefits of Using Composer

Composer tracks which versions of packages you have installed in a file called composer.lock, which is intended to be committed to version control, so that when the project is cloned in the future, simply running composer install will download and install all the project's dependencies. Composer de...

PHP • Composer Dependency Manager

Pattern matching with bindings

It is possible to bind values to names using @: struct Badger { pub age: u8 } fn main() { // Let's create a Badger instances let badger_john = Badger { age: 8 }; // Now try to find out what John's favourite activity is, based on his age match badger_john.age { ...

Rust • Pattern Matching

Basic pattern matching

// Create a boolean value let a = true; // The following expression will try and find a pattern for our value starting with // the topmost pattern. // This is an exhaustive match expression because it checks for every possible value match a { true => println!("a is true"), ...

Rust • Pattern Matching

Create cryptographically secure random numbers

By default the Python random module use the Mersenne Twister PRNG to generate random numbers, which, although suitable in domains like simulations, fails to meet security requirements in more demanding environments. In order to create a cryptographically secure pseudorandom number, one can use Syst...

Python Language • Random module

Simple Bar Chart

index.html <!doctype html> <html> <head> <title>D3 Sample</title> </head> <body>  <div id=...

d3.js • Getting started with d3.js

Lazy, thread-safe Singleton (using Double Checked Locking)

This thread-safe version of a singleton was necessary in the early versions of .NET where static initialization was not guaranteed to be thread-safe. In more modern versions of the framework a statically initialized singleton is usually preferred because it is very easy to make implementation mistak...

C# Language • Singleton Implementation

List all contributions grouped by author name

git shortlog summarizes git log and groups by author If no parameters are given, a list of all commits made per committer will be shown in chronological order. $ git shortlog Committer 1 (<number_of_commits>): Commit Message 1 Commit Message 2 ... Committer 2 (<number_of_...

Git • Browsing the history

Loop control with break, next, and redo

The flow of execution of a Ruby block may be controlled with the break, next, and redo statements. break The break statement will exit the block immediately. Any remaining instructions in the block will be skipped, and the iteration will end: actions = %w(run jump swim exit macarena) index = 0 ...

Ruby Language • Control Flow

Assigning to a delegate by lambda

Lambdas can be used to create anonymous methods to assign to a delegate: Func<int,int> addOne = x => x+1; Note that the explicit declaration of type is required when creating a variable this way: var addOne = x => x+1; // Does not work

C# Language • Delegates

hasattr function bug in Python 2

In Python 2, when a property raise a error, hasattr will ignore this property, returning False. class A(object): @property def get(self): raise IOError class B(object): @property def get(self): return 'get in b' a = A() b = B() print 'a hasattr get:...

Python Language • Incompatibilities moving from Python 2 to Python 3

Univariate Geometric Brownian Motion

The dynamics of the Geometric Brownian Motion (GBM) are described by the following stochastic differential equation (SDE): I can use the exact solution to the SDE to generate paths that follow a GBM. Given daily parameters for a year-long simulation mu = 0.08/250; sigma = 0.25/sqrt(...

MATLAB Language • Financial Applications

Basic Usage for Mirror

Creating the class to be the subject of the Mirror class Project { var title: String = "" var id: Int = 0 var platform: String = "" var version: Int = 0 var info: String? } Creating an instance that will actually be the subject of the mirror. Also he...

Swift Language • Reflection

Absolute Position

When absolute positioning is used the box of the desired element is taken out of the Normal Flow and it no longer affects the position of the other elements on the page. Offset properties: top left right bottom specify the element should appear in relation to its next non-static containing ...

CSS • Positioning

Unmodifiable Collection

Sometimes it's not a good practice expose an internal collection since it can lead to a malicious code vulnerability due to it's mutable characteristic. In order to provide "read-only" collections java provides its unmodifiable versions. An unmodifiable collection is often a copy of a mod...

Java Language • Collections

Autosquash: Committing code you want to squash during a rebase

Given the following history, imagine you make a change that you want to squash into the commit bbb2222 A second commit: $ git log --oneline --decorate ccc3333 (HEAD -> master) A third commit bbb2222 A second commit aaa1111 A first commit 9999999 Initial commit Once you've made your change...

Git • Squashing

Bootstrapping

Now that the routes are defined, we need to let our application know about the routes. To do this, bootstrap the provider we exported in the previous example. Find your bootstrap configuration (should be in main.ts, but your mileage may vary). //main.ts import {bootstrap} from '@angular/platfo...

Angular 2 • Routing (3.0.0+)

Imaginary Numbers

Imaginary numbers in Python are represented by a "j" or "J" trailing the target number. 1j # Equivalent to the square root of -1. 1j * 1j # = (-1+0j)

Python Language • Math Module

Copying a range of commits from one branch to another

git cherry-pick <commit-A>..<commit-B> will place every commit after A and up to and including B on top of the currently checked-out branch. git cherry-pick <commit-A>^..<commit-B> will place commit A and every commit up to and including B on top of the currently checked-out...

Git • Cherry Picking