I was happily playing with my shiny new prime-number-checker, trying out how loops work in C++. When I started entering stupidly big numbers, something strange happened. ./main Enter a number: 5784320578432578493207508493 Congratulations, it's prime! Except, that is not actually a prime number. I can’t have typed a prime number by randomly banging on the keypad. What’s going on? I didn’t code any input sanitization in my prime-number-checker, so let’s check what my program actually gets. Read more

My first steps: I have enrolled for a Pluralsight course I have installed a C++ syntax extension on my beloved editor. Discovery #1: Classes feel like language extensions In Go, primitive types are special. Some properties only apply to them; for example, there is no way of defining a behaviour for make(myType). Every primitive type brings its own built-in constructor, and custom types inherit the constructor from the primitive type they’re based on. Read more

A long time ago, I started programming with Python. Everything was great and I was happy. Then I discovered Go. Everything was fast and portable and powerful. This is my first day into learning C++. Why? A SQL metaphor I used to be contributor to an opensource Go database adaptor: something like an object-relational mapper. Back then, I was fascinated by the idea of abstracting away SQL from my applications. Read more

Browsers let us save passwords and to retrieve them. This way, we can use strings too long and complex to be remembered. Some browsers, with or without the support of external password managers, generate new passwords for us and manage them seamlessly. However most of the time, everything regarding passwords is still based on the ability of the browser of guessing which input field contains a username, and which one contains a password. Read more

Build with Modules, Ship from Scratch If you use dep, check out this post instead. Goals: The application executable is compiled inside a container, in order to boost reproducibility The resulting image must be as small as possible The application must run in a container as secure as possible: an unprivileged user in a minimal environment The application must be able to make HTTPS calls It is a multistage Dockerfile: the first throwaway stage is used for building, while the final image will only contain the compiled binary executable. Read more

In this video, Robert Martin uses Kotlin and JUnit to illustrate his Three Laws of TDD. But what about Go? Follow me and challenge the master! We will walk in his footsteps with the only help of Brad Fitzpatrick’s checkFunc pattern. The Three Laws You are not allowed to write any production code unless it is to make a failing unit test pass. You are not allowed to write any more of a unit test than is sufficient to fail; and compilation failures are failures. Read more

Build With Dep, Ship From Scratch For Go 1.11 modules, check this post instead. In a devops environment, pushing some code to the repository is not enough. You have to ship it. And the first step is often writing a Dockerfile. The goals: The code has to be compiled in a container, to boost the chances my build will be reproducible. Use dep for fetching the dependencies in case the vendor folder is not committed alongside with the code. Read more

Recently, I have been working on an event-sourced application built around Command-Query Responsibility Segregation (CQRS). My job was to figure out how to implement a new command in Go. In order to act on a given object, we have to build the current state of that object out of the events that created and modified it. Here I want to show how I have come up with the applier interface to represent the Event logic. Read more

I used to spend an unreasonable amount of time thinking about how to begin writing a test. I googled test patterns in Go. Many people seem to rely on external dependencies for assertions. And in fact, I understand that generic (aha!) functions like isNil(v interface{}) bool can initially bring speed to the development. But in the long run, I think that embracing the true strongly-typed nature of Go, instead of just searching for a way around it, is more rewarding. Read more