Tutorial by Examples: g

Comprehensions involving tuples

The for clause of a list comprehension can specify more than one variable: [x + y for x, y in [(1, 2), (3, 4), (5, 6)]] # Out: [3, 7, 11] [x + y for x, y in zip([1, 3, 5], [2, 4, 6])] # Out: [3, 7, 11] This is just like regular for loops: for x, y in [(1,2), (3,4), (5,6)]: print(x+y) ...

Python Language • List comprehensions

Using Jackson Object Mapper

Pojo Model public class Model { private String firstName; private String lastName; private int age; /* Getters and setters not shown for brevity */ } Example: String to Object Model outputObject = objectMapper.readValue( "{\"firstName\":\"J...

Java Language • JSON in Java

This is confusing. Why not just always use parentheses?

Parentheses are used to enclose the arguments of function calls. Using them for procedure calls can cause unexpected problems. Because they can introduce bugs, both at run-time by passing a possibly unintended value to the procedure, and at compile-time by simply being invalid syntax. Run-time Re...

VBA • Procedure Calls

Lexicographical comparison

Two std::strings can be compared lexicographically using the operators ==, !=, <, <=, >, and >=: std::string str1 = "Foo"; std::string str2 = "Bar"; assert(!(str1 < str2)); assert(str > str2); assert(!(str1 <= str2)); assert(str1 >= str2); assert...

C++ • std::string

Attach object to another existing object (association)

It's possible to attach an object to an existing object as if there was a new property. This is called association and allows one to extend existing objects. It can be used to provide storage when adding a property via a class extension or otherwise add additional information to an existing object. ...

Objective-C Language • Low-level Runtime Environment

Augmenting methods using Method Swizzling

The Objective-C runtime allows you to change the implementation of a method at runtime. This is called method swizzling and is often used to exchange the implementations of two methods. For example, if the methods foo and bar are exchanged, sending the message foo will now execute the implementation...

Objective-C Language • Low-level Runtime Environment

Creating NSArray instances

NSArray *array1 = [NSArray arrayWithObjects:@"one", @"two", @"three", nil]; NSArray *array2 = @[@"one", @"two", @"three"];

Objective-C Language • NSArray

Embedding external SVG files in HTML

You can use the <img> or <object> elements to embed external SVG elements. Setting the height and width is optional but is highly recommended. Using the image element <img src="attention.svg" width="50" height="50"> Using <img> does not allo...

HTML • SVG

Inline SVG

SVG can be written directly into a HTML document. Inline SVG can be styled and manipulated using CSS and JavaScript. <body> <svg class="attention" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" viewBox="0 0 1000 1000&qu...

HTML • SVG

Embedding SVG using CSS

You can add external SVG files using the background-image property, just as you would do with any other image. HTML: <div class="attention"></div> CSS: .attention { background-image: url(attention.svg); background-size: 100% 100%; width: 50px; height: ...

HTML • SVG

Splitting

You can split a string into an array of parts, divided by a separator character. NSString * yourString = @"Stack,Exchange,Network"; NSArray * yourWords = [yourString componentsSeparatedByString:@","]; // Output: @[@"Stack", @"Exchange", @"Network&quot...

Objective-C Language • NSString

Searching for a Substring

To search if a String contains a substring, do the following: NSString *myString = @"This is for checking substrings"; NSString *subString = @"checking"; BOOL doesContainSubstring = [myString containsString:subString]; // YES If targeting iOS 7 or OS X 10.9 (or earlier)...

Objective-C Language • NSString

Work with Arrays, Not With Ranges

Office Blog - Excel VBA Performance Coding Best Practices Often, best performance is achieved by avoiding the use of Range as much as possible. In this example we read in an entire Range object into an array, square each number in the array, and then return the array back to the Range. This accesse...

excel-vba • VBA Best Practices

Using Range with various Linq methods

You can use the Enumerable class alongside Linq queries to convert for loops into Linq one liners. Select Example Opposed to doing this: var asciiCharacters = new List<char>(); for (var x = 0; x < 256; x++) { asciiCharacters.Add((char)x); } You can do this: var asciiCharacter...

C# Language • LINQ Queries

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

Nesting Components

A lot of the power of ReactJS is its ability to allow nesting of components. Take the following two components: var React = require('react'); var createReactClass = require('create-react-class'); var CommentList = reactCreateClass({ render: function() { return ( <div className...

React • Components

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

Matching multiple patterns

It's possible to treat multiple, distinct values the same way, using |: enum Colour { Red, Green, Blue, Cyan, Magenta, Yellow, Black } enum ColourModel { RGB, CMYK } // let's take an example colour let colour = Colour::Red; let model = match ...

Rust • Pattern Matching

Conditional pattern matching with guards

Patterns can be matched based on values independent to the value being matched using if guards: // Let's imagine a simplistic web app with the following pages: enum Page { Login, Logout, About, Admin } // We are authenticated let is_authenticated = true; // But we aren't admins...

Rust • Pattern Matching