Tutorial by Examples: ar

struct MetricDistance { var distanceInMeters: Double init(fromCentimeters centimeters: Double) { distanceInMeters = centimeters / 100 } init(fromKilometers kilos: Double) { distanceInMeters = kilos * 1000 } } let myDistance = MetricDistance(fromCentim...

import locale locale.setlocale(locale.LC_ALL, '') Out[2]: 'English_United States.1252' locale.currency(762559748.49) Out[3]: '$762559748.49' locale.currency(762559748.49, grouping=True) Out[4]: '$762,559,748.49'

So let's suppose you want to iterate only between some specific lines of a file You can make use of itertools for that import itertools with open('myfile.txt', 'r') as f: for line in itertools.islice(f, 12, 30): # do something here This will read through the lines 13 to 20 as i...

You can use flatMap(_:) in a similar manner to map(_:) in order to create an array by applying a transform to a sequence's elements. extension SequenceType { public func flatMap<T>(@noescape transform: (Self.Generator.Element) throws -> T?) rethrows -> [T] } The difference with...

Given a String and a Character let text = "Hello World" let char: Character = "o" We can count the number of times the Character appears into the String using let sensitiveCount = text.characters.filter { $0 == char }.count // case-sensitive let insensitiveCount = text.low...

Controllers have access to HTTP parameters (you might know them as ?name=foo in URLs, but Ruby on Rails handle different formats too!) and output different responses based on them. There isn't a way to distinguish between GET and POST parameters, but you shouldn't do that in any case. class UsersCo...

class UsersController < ApplicationController def index respond_to do |format| format.html do render html: "Hello #{ user_params[:name] } user_params[:sentence]" end end end private def user_params if params[:name] == "john&quo...

This function runs an AJAX call using GET allowing us to send parameters (object) to a file (string) and launch a callback (function) when the request has been ended. function ajax(file, params, callback) { var url = file + '?'; // loop through object and assemble the url var notFirst ...

From guides.rubyonrails.org: Instead of generating a model directly . . . let's set up a scaffold. A scaffold in Rails is a full set of model, database migration for that model, controller to manipulate it, views to view and manipulate the data, and a test suite for each of the above. Here's a...

To separate a URL into its individual components, use parse_url(): $url = 'http://www.example.com/page?foo=1&bar=baz#anchor'; $parts = parse_url($url); After executing the above, the contents of $parts would be: Array ( [scheme] => http [host] => www.example.com [path...

The StringBuffer, StringBuilder, Formatter and StringJoiner classes are Java SE utility classes that are primarily used for assembling strings from other information: The StringBuffer class has been present since Java 1.0, and provides a variety of methods for building and modifying a "buf...

// Generic types are declared using the <T> annotation struct GenericType<T> { pub item: T } enum QualityChecked<T> { Excellent(T), Good(T), // enum fields can be generics too Mediocre { product: T } }

Generics types can have more than one type parameters, eg. Result is defined like this: pub enum Result<T, E> { Ok(T), Err(E), }

Git is pretty good at identifying binary files, but you can explicitly specify which files are binary. Create a .gitattributes file in the project root containing: *.png binary binary is a built-in macro attribute equivalent to -diff -merge -text.

The jQuery API may be extended by adding to its prototype. For example, the existing API already has many functions available such as .hide(), .fadeIn(), .hasClass(), etc. The jQuery prototype is exposed through $.fn, the source code contains the line jQuery.fn = jQuery.prototype Adding functio...

The following code will show week of the year number on the left side of the datepicker. By default the week start on Monday, but it can be customized using firstDay option. The first week of the year contains the first Thursday of the year, following the ISO 8601 definition. <input type="t...

6 An array can be destructured when being assigned to a new variable. const triangle = [3, 4, 5]; const [length, height, hypotenuse] = triangle; length === 3; // → true height === 4; // → true hypotneuse === 5; // → true Elements can be skipped const [,b,,c] = [1, 2, 3, 4]; co...

This design pattern is useful for generating a sequence of asynchronous actions from a list of elements. There are two variants : the "then" reduction, which builds a chain that continues as long as the chain experiences success. the "catch" reduction, which builds a chain t...

There is also a way to have a single method accept a covariant argument, instead of having the whole trait covariant. This may be necessary because you would like to use T in a contravariant position, but still have it covariant. trait LocalVariance[T]{ /// ??? throws a NotImplementedError de...

Since lambda functions are values themselves, you store them in collections, pass them to functions, etc like you would with other values. // This function takes two integers and a function that performs some operation on the two arguments fn apply_function<T>(a: i32, b: i32, func: T) -> ...