Make delegated methods private in Rails
Recently, I came across some of my old code that uses Rails’ delegate method. Take a look at the following example, where I’m delegating a couple of methods to an instance variable, but want to make them private. class UserDecorator def initialize(user) @user = user end def full_name "#{first_name} #{last_name}" end private delegate :first_name, :last_name, to: :@user end My intention was to make
Recurring events in Rails
Modeling recurring events in a calendar is an interesting problem to solve. There are many different scenarios in which you might need to model recurring events, but in this article I will walk through a simple example of weekly recurring events in a Rails app. Although this post covers most of the code needed for the example, I will skip over some of the details (such as views), and you will have
Writing and publishing an Elixir library
Recently, I wrote some code to query Google Books API, and extracted it into a Hex package. In this article, we will walk through the process of publishing an Elixir package to hex.pm. Let’s start by generating a new project called google_books using mix: mix new google_books The files we will be working with are mix.exs and lib/google_books.ex, which contains the GoogleBooks module where we will
Demystifying @tenderlove's homeopathic code optimizations
Demystifying @tenderlove's homeopathic code optimizations 05 Jun 2015 At the Keep Ruby Weird conference, Aaron Patterson, aka @tenderlove, gave a hilarious keynote talk where he mentioned homeopathic code optimizations. If you haven’t watched it yet, go watch it now. For those that haven’t watched the video, here’s the idea: he talks about a program dilute.rb, that takes another ruby program and “
Presenters in Rails
When your models are bloated with methods that are only used in views, it might be a good time to refactor them. Moving that logic into helper modules might be OK in some cases, but as the complexity of your views grows, you might want to look at presenters. Presenters give you an object oriented way to approach view helpers. In this post, I will walk through how we refactored our views to use pre
What's new in Rails 5?
Rails 5.0 is almost here! The first beta version has been released already, and you can try out some of the shiny new features right away. So what are the new features? Let’s take a quick tour of the new features and major changes. ActionCable Websocket support in Rails is the most talked about feature in Rails 5. This will make it super easy to add realtime features to your app. If you’re plannin
What's new in Ruby 2.3?
Ruby 2.3.0 will be released this Christmas, and the first preview release was made available a few weeks ago. I’ve been playing around with it and looking at what new features have been introduced. # Install using RVM rvm install 2.3.0 # Using Rbenv brew upgrade ruby-build --HEAD rbenv install 2.3.0 Safe navigation operator A new operator (&.) has been introduced. It can be very useful in cases wh
Building a chat application using Elixir and Phoenix
Building a chat application using Elixir and Phoenix 11 Jul 2015 I’ve been looking at Phoenix channels lately, and going through Chris McCord’s Phoenix chat example gives a great intro to getting started with it. In this post, we’ll be walking through the process of building the same app step by step. We’ll use Elixir 1.0.5 and Phoenix 1.0.0. (This was originally written for Phenix 0.14, but was l
Getting started with Rails 5's ActionCable and websockets
Getting started with Rails 5's ActionCable and websockets 17 Jul 2015 ActionCable is the websockets framework that ships with Rails 5. It aims to simplify the addition of realtime features to Rails apps. In this tutorial, we will explore ActionCable by building a simple chat application. Let’s get started by installing the pre-release version of Rails (5.0.0.beta). Once the final 5.0.0 version of
User authentication from scratch in Elixir and Phoenix
User authentication from scratch in Elixir and Phoenix 30 Jun 2015 In my previous post about Phoenix, we built a very simple blog app. We only added the ability to post content, but there’s no user authentication system. In this post, we will add user authentication to the app. There are excellent authentication libraries out there like passport and addict, but here we’ll be writing authentication
Infinity in Ruby
Have you ever wondered how Ruby handles infinity? We’ve all run into the divide-by-zero error when diving an integer by zero, but things are different in case of floating point numbers. 1/0 #=> ZeroDivisionError 1.0 / 0 #=> Infinity 1 / 0.0 #=> Infinity Infinity #=> NameError: uninitialized constant Infinity As you can see above, Ruby gives you a value that represents infinity when a floating poin
Getting started with Phoenix: Building a scaffolded CRUD app
Getting started with Phoenix: Building a scaffolded CRUD app 30 May 2015 Lately I’ve been looking at the Phoenix web framework for the Elixir language. Phoenix has taken a lot of inspiration from Rails, and the structure of a project feels somewhat familiar if you’ve worked with Rails. To get familiar with the framework, I’m starting with a simple CRUD app using Phoenix’s scaffolding generator. Th
Nithin Bekal
Hi, I'm Nithin. I am a software developer based in Ottawa, Canada. This is my blog about programming. Ruby is my programming language of choice and the topic of most of the posts here, but I occasionally also write about the books I read, or other technologies that I'm tinkering with.
Writing Ruby gems
This article is about building a gem from scratch. The recommended way to create a gem today is to use bundler’s bundle new <gemname> command. This article is meant to take a closer look at what is generated by such tools by building it by hand. Writing a Ruby gem is a lot easier than it sounds. Many tutorials about writing gems recommend using something like (Jeweler or Hoe) bundler to create the
Export to CSV in Rails
Exporting data to CSV from a Rails app is as simple as adding a respond_to block to the controller action and setting the proper response headers. As an example, let’s consider a users#index action which lists the users for admin. Now if you want to allow the admin to download the list as CSV, this is how it can be done: Require Ruby’s built in CSV library in ApplicationController. require 'csv' I
Decorator pattern in Ruby
Decorators allow us to add behavior to objects without affecting other objects of the same class. The decorator pattern is a useful alternative to creating sub-classes. We will look at an example where we use subclassing to solve a problem, and then look at how decorator objects provide a better solution. Imagine we have a Burger class with a cost method that returns 50. class Burger def cost 50 e
When to use protected methods in Ruby
The protected method visibility in Ruby is one of its more confusing aspects. I recently took a closer look at it, and found that it has an interesting use case. First let’s take a quick look at how public and private method visibility works. class Foo def hello 'Hello' end private def secret 'abracadabra' end end foo = Foo.new foo.hello #=> 'Hello' foo.secret #=> NoMethodError Here, calling foo.h
Flip flop operator in Ruby
The flip flop operator is one of those weird features of Ruby that most people aren’t even aware of. It’s one of the many Perlisms that sneaked into Ruby, but hasn’t caught on. In this post, we will look at what flip-flop operators are, and where you can use them. What is it? The flip flop operator is a range (..) operator used between two conditions in a conditional statement. It looks like this:
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What's new in Ruby 2.6
Feature flags in Phoenix projects using laboratory