This is the second part of my series of articles on how to write a regex engine in Python. In this article, we’re going to set up the environment and build the lexer.

In the previous article, we spoke about grammar and what we need to complete this project.

It’s now time to finally dig into the coding part.

Set Up The Environment

To set up the environment we first need to create a folder for the project and the virtualenv we’ll use for it.

mkdir pyregex
cd pyregexpython3 -m venv venv
source venv/bin/activate

For this project, we will use a couple of…

In this series of articles, we will follow the steps to build a RegEx Engine in Python. I chose Python over the many alternatives for a few reasons:

1. It is well integrated with the Linux command line
2. Because yes.

In a way, I find Python to be a “less verbose version of Java” and a “less confusing version of JavaScript”, which were the other two alternatives I considered.

Please let me explain before get mad at me.
Before starting this project I had no idea how things should be done, how to code the various modules, and so on. …

The CIA triad is a widely used acronym in information security standing for:

• Confidentiality
• Integrity
• Availability.

These three are the fundamental properties of information to protect.

Thinking about these three when designing for security is crucial to build a robust system.

Let’s briefly analyze them in the order proposed by the acronym.

Confidentiality

Confidentiality is the property of data to remain secret between the sender and the receiver.

The most mechanism to maintain confidentiality is encryption.

When you encrypt a message, you obscure it by transforming it into a seemingly meaningless one.

After encryption, the only way to restore a message…

CODEX

You may be wondering what’s the topic of this article. Perhaps you spotted the reference to Kendrick Lamar’s How Much A Dollar Cost.
So, what do Kendrick’s song and bytes have in common? Nothing, to be honest.

This whole article’s a mere storytelling experiment. Now, without further ado, let’s begin our story.

An Expensive Lesson

How much a byte really cost?
The question is detrimental, paralyzin’ my thoughts

It was 1996 — June the 4th precisely — and the European Space Agency was ready to launch a brand new rocket named Ariane 5 from its base in Kourou, French Guiana. …

Prerequisites: having Python installed on your pc or being registered for Google Colaboratory.

Step 0

First of all, create a new directory for the project (if you use Google Colaboratory skip to step 1)

mkdir my_bar_chart_race

And create a new virtual environment, and activate it:

python3 -m venv venv
source venv/bin/activate

Step 1

If you haven’t already, install pandas

pip3 install pandas

Install the library we’ll use to create the bar chart race named, you won’t guess it, bar_chart_race

pip3 install bar_chart_race

Step 2

Now that we have the necessary libraries installed, let’s load our data.

In this tutorial, we’ll create a bar chart animation of…

Git is a DVCS: Distributed Version Control System.

Basically, with git you and your team can cooperate to create, modify, extend, maintain code working in parallel on the same codebase, without worrying about “breaking” the code.

When you want to develop a project using git you create a repository — a directory containing your project’s code and a .git subdirectory used by git itself to keep track of everything.

Note: repositories are often called repo for brevity.

The command to initialize a folder is:

git init 

to initialize the current folder, or

git init <directory_name>

to initialize a specific directory.

Keep Track Of a File

…

Arrow functions are those weird functions using a funny syntax mimicking how humans write or draw them on paper:

(param1, param2) => { /* do something */ }

Are they just a shorter way to write function, or is there more?

The answer is yes, they’re mostly a shorter way to write functions, but there are some little differences.

Arrow functions are anonymous

The first thing you may note from the above snippet is that arrow functions haven’t got a name — they’re anonymous.

For instance, you cannot write something like this:

functionName(param) => { /* do smth */ }

But you can get…

What are JavaScript closures?

MDN web docs give this great definition of what a closure is:

A closure is the combination of a function bundled together (enclosed) with references to its surrounding state (the lexical environment). In other words, a closure gives you access to an outer function’s scope from an inner function. In JavaScript, closures are created every time a function is created, at function creation time.

A practical example

This example comes from this series about closures that I’ve made, but with a simpler syntax to be more beginner-friendly, and with some improvements, because in series you must be short:

In this example, the…