99 Bottles of OOP book review

Review of one of the most popular OOP books, written by a skilled coder 
28 July 2017   1035

Dynamic, open source programming language with a focus on simplicity and productivity, it has an elegant syntax that is natural to read and easy to write.

“99 bottles of OOP” is the second Sandi Metz’s book, co-authoring Katrina Owen. I was interested in this book for several reasons: first of all, I like the authors and their activities, secondly, I like the topic and the name of the book is awesome. I believe that writing the solid book based on the discussions about one kata, especially the one about “99 bottles of beer” is an outstanding idea by itself.

99 bottles of OOP
99 bottles of OOP

The authors recommend spending a half an hour on solving the “99 bottles of beer” kata before reading the book.

In the beginning of the book, there are several solutions which are evaluated with the help of metrics and common sense. When the best solution (for now) is chosen, the new requirements appear. Now you have to adapt your code so that it would become open for the easy change. In the following chapters, you’ll find the refactoring steps with the detailed descriptions and rationales.

Make the change easy (warning: this may be hard), then make the easy change.

Kent Beck
Programming Coach, Facebook

This book was written as the alternative to visiting a workshop, so it’s important to reproduce all steps and imagine that you are at the event :)

The authors imply, that “99 bottles” may totally change your assumptions on TDD. The code is changed by very small steps, and after each change, you must run the tests and they should remain green. If not, revert and make another change.

If you are an experienced programmer and haven’t used such approach before, it may be hard for you to use it. It’s not easy to me to use all rules, especially when I work on large projects, that contain legacy code. But it’s useful to explore this approach: e.g. sometimes the right abstractions will “appear” after you make several small steps. It may be easier to try this approach while solving katas first.

According to the authors, the book has 2 goals:

  • supply you with the concrete refactoring techniques for everyday use
  • make you fall in love with polymorphism

I guess we shouldn’t think of “99 bottles” as finding the right solution for the specific task. It’s more of a demonstration of refactoring rules and oop principles, using this example.

Refactoring is one of my favorite topics, so I liked the book. It helped me to organize my knowledge, look at TDD from a different angle and use this approach more often.

My notes on the book

How To Start an Open Source Project

Personal experience on the open source project; doing it effectively without mistakes
26 January 2018   1238

My name is Dmitriy Strukov and I’m Ruby developer. Today I want to share my experience creating an open source solution. I will talk about what steps the project should take, how to choose the right functionality for the first release, and what mistakes I faced personally when creating my open source project.

Half a year ago, I got the idea that it would be good to create an open source project. Instead of test tasks for the interview, it would be enough for me to send a link to the repository. The prospect of helping colleagues with the solution to their everyday problems inspired me.

I’ve always disliked gems for creating administration panels. Any extra movement needs to redefine the class, and for change fields you need to make changes to the files. After thinking and conversing with colleagues, I decided to create a new library which would be flexible and would not require dashboards or configuration files.


Initially, the project was focused on the Ruby ecosystem, but this would limit the target audience of such a solution. SimpleAdmin is a cross-platform solution for administrative panels, working as a third party service. Obtaining data from the database from the main application works with the help of a plugin. In the Ruby on Rail it engine, in which the necessary endpoints are created. In the near future, the launch of a prototype is planned.

Determine the goals

Every open source project solves a specific problem. Talk with colleagues, chats, forums, and share your idea. It all helps you on the first steps to understand important things, like which solutions already exist, and to hear criticism. Talk with people who already have open source projects. They can give you very valuable advice, so don’t be afraid to ask and take the initiative.

One important bit of advice which I got at that stage is to pay attention in the first place on the documentation of the project. You can have a very good project, but no one will spend the time to understand how it works.

The most important aspect, without which further steps are impossible, is motivation. The idea of the project should inspire you primarily. Most often people get used to the tools with which they work and fall into a comfort zone, so external opinions may be ambiguous.


The choice of a certain task manager is a matter of taste. It should have a clear picture of the tasks and stages of your project.

Divide tasks into sub-tasks. Ideally, if one task does not take more than 3–4 hours, it is important to enjoy the implementation of small tasks. This will help to avoid burnout and loss of motivation.

I use pivotal tracker . The main advantage is a free version for open source projects where you can sort tasks by type (feature, bug, chore, release), and group them into releases and determined deadlines.


Every open source project should contain these things:

  • Open Source license
  • Contributing guidelines
  • Changelog

The README file not only explains how to use your project, but also the purpose of your project. If you do not know how to properly write a README file, you can look at other known open source projects or use a template .

The license guarantees that others can use, copy and modify the source code of the project. You need to add this file to each repository with your open source project. MIT and Apache 2.0 GPLv3 are the most popular licenses for open source projects. If you are not sure what to choose, you can use this convenient service .

The CONTRIBUTING file will help other developers contribute to the project. At the first steps of the project, it is not necessary to pay close attention to this file. You can use the already prepared template from another project.

Changelog contains a supported, chronologically-ordered list of significant changes for each version. As with the CONTRIBUTING file, I do not advise paying special attention to this at an early stage.


To track important changes for users and contributors, there is a semantic version . The version number contains numbers and adheres to the following pattern X.Y.Z.

  • X major release
  • Y minor release
  • Z patch release

Continuous integration / Continuous delivery

To automatically run tests and build, I use Travis CI. It’s also a good idea to add badges to display the successful assembly of the build in the wizard, the test coverage (Codecov), and the documentation (Inch CI).

After each new commit or merge in the master, I automatically have a deploy on Heroku (very convenient integration with GitHub). All tools are absolutely free for an open source project.

My mistakes

To analyze the initial stage, I had an idea, but there was no clear plan. I decided that I wanted to do this without having a clear idea of how much time it would take or a specific representation of the functions that would be in the first version of the library. I had just a lot of desire and lack of a clear plan.

Also, after reading the history of other projects (not only open source), I noticed that at an early stage, some plans are too optimistic. They need a reassessment of their strengths and capabilities. But it’s not easy to find time each day to write a new feature in the project. Most of the tasks eventually had to be weeded out, leaving the necessary minimum for MVP.