This post assumes basic understanding of recursion and Ruby.

What is tail call optimization

Tail call optimization (TCO) is an optimization strategy for tail-recursive procedures. It is useful in preventing stack overflow when using recursion because it limits the call stack size of a recursive procedure to one.

In this post, I will explain the basics of how a method call works in Ruby. I’ll assume that readers have some familiarity with Ruby language.

The post is in two parts. The first part covers what you need to know about typical Ruby program. It covers: ancestors hierarchy, class inheritance, and module include and prepend.

The second part digs into tools that are used less often. It covers: singleton method, singleton class, and class methods.

In this post, I will explain the basics of how a method call works in Ruby. I’ll assume that readers have some familiarity with Ruby language.

The post is in two parts. The first part covers what you need to know about typical Ruby program. It covers: ancestors hierarchy, class inheritance, and module include and prepend.

The second part digs into tools that are used less often. It covers: singleton method, singleton class, and class methods.

One of the best tips I got about writing a blog post is to write posts that I would have wanted to read a year ago. This is one of them. I hope this would clarify misconceptions commonly held by beginners about type system.

This post is adapted from my talk at Seoul Elixir Meetup on November 16, 2016.

Elixir might not be the first language that comes to your mind when you think about which programming language to teach to beginners. Languages like Python, Ruby, JavaScript, C/C++, or Java are more popular choices. But I think Elixir has some unique advantages that makes it a serious candidate.

This post is adapted from my talk at Seoul Elixir Meetup on November 16, 2016.

Elixir might not be the first language that comes to your mind when you think about which programming language to teach to beginners. Languages like Python, Ruby, JavaScript, C/C++, or Java are more popular choices. But I think Elixir has some unique advantages that makes it a serious candidate.

tl;dr

Use :crypto.exor/2 from crypto module in Erlang standard library.

Chronicle of My Decent into Rabbit Hole

It started with a simple quiz from Cryptography course in Coursera. I was given a plain text (pt) and a cipher text (ct) encrypted with one-time pad, so I just had to do an XOR of ct and pt to figure out the one-time pad key.

I didn’t know how to do that in Elixir, so I decided to figure it out.

So I’ve finally caught up with all the old Ruby Rogues episodes. At this point there are 283 episodes in total, each about an hour long. I started listening to the podcast around the beginning of 2016, so that means I listened to at least an hour of Ruby Rogues everyday. It’s no wonder that I can vividly replay Chuck Maxwood, the host of the show, and other long-time panelists’ voices and laughters in my head.

First of all, I would like to thank Chuck, panelists, guests, and the other staff who brought this show together and who are still keeping this show going over 5 years. It’s hard to describe how tremendously valuable this show has been to me, and how grateful I am for its existence.

Just like most of new Ruby on Rails developers, I ended up creating a Lovecraftian nightmare of huge tangled models in my first project. It’d have been nice to have an experienced developer to prevent me from making that mess. Unfortunately, I didn’t have one. I had to figure a way out of it on my own.

Reading through numerous blog posts, I found out that it was not just me. This problem was caused by the way Rails used Active Record pattern, and was prevalent among many Rails developers. I could even see some kind of historical eras of Rails application structure: the Fat Controller Age, the Fat Model Age, and the Plain Old Ruby Object Age. There were other solutions too. For example, Ruby Object Mapper and Hanami framework used Data Mapper pattern to replace Active Record pattern entirely.

When many people end up making the same mistakes, it can no longer be attributed to the individuals. That’s a sign that there’s a design flaw in Rails that repeatedly misleads people into making those mistakes. But I’m fine with the fact that it has flaws. After all, there’s no such thing as a perpetually perfect system, and Rails got far more things right than wrong.

I needed an authentication system for my application, so I looked at the existing libraries for Elixir and found some promising ones, such as ueberauth, guardian, and openmaize.

I started to look into how they did things, then I came across a discussion about JWT in authentication. Now then what the hell is JWT? All I know at this point is that it’s another acronym that I don’t know. I swear that this field is at least as obsessed with acronyms as the military, and that’s definitely not a compliment.