With a foreword by Ross Tuck Today I've released the revised edition of my latest book "Style Guide for Object Design" . Over the past few weeks I've fixed many issues, smaller and larger ones. Ross Tuck and Laura Cody have read the manuscript and provided me with excellent feedback, which has helped me a lot …
You say "convention over configuration;" I hear "ambient information stuck in someone's head." You say "configuration over hardcoding;" I hear "information in a different language that must be parsed, can be malformed, or not exist." — Paul Snively (@paul_snively) March 2, 2019 Dependency injection is very …
Cyrille Martraire: Domain modeling towards First Principles This was a talk from the first day, but it required some more processing before writing about it. Cyrille is one of my favorite speakers. He's fast, funny and brings a lot of interesting topics to the table. So many that it's sometimes hard to keep …
Eric Evans: Keynote ("Language in Context") Starting out with the basics (words have meaning within a context; when we make the boundary of this context explicit we end up with a bounded context ), Eric discussed two main topics: the Big Ball of Mud , and bounded contexts in the context (no pun intended) of …
All of a sudden it became book-writing season. It began in August when I started revising my second book, "Principles of Package Design". Apress had contacted me about adopting it, and they didn't want to change a lot about it. However, the book was from 2015 and although I had aimed for it to be "timeless", some …
In part 1 of this short series (it's going to end with this article) we covered how you can test-drive the queries in a repository class . Returning query results is only part of the job of a repository though. The other part is to store objects (entities), retrieve them using something like a save() and a …
There's something I've only been doing since a year or so, and I've come to like it a lot. My previous testing experiences were mostly at the level of unit tests or functional/system tests. What was left out of the equation was integration tests. The perfect example of which is a test that proves that your custom …
When you're looking at a function (an actual function or a method), you can usually identify several blocks of code in there. There are pre-conditions , there's the function body , and there may be post-conditions . The pre-conditions are there to verify that the function can safely proceed to do its real job . …
I recently wrote about when to add an interface to a class . After explaining good reasons for adding an interface, I claim that if none of those reasons apply in your situation, you should just use a class and declare it "final". PHP 5 introduces the final keyword, which prevents child classes from overridin…
Last week I wrote about when to add an interface to a class . The article finishes with the claim that classes from the application's domain don't usually need an interface. The reason is that domain code isn't going to be swapped out with something else. This code is the result of careful modelling work that's done …
I'm currently revising my book "Principles of Package Design" . It covers lots of design principles, like the SOLID principles and the lesser known Package (or Component) Design Principles. When discussing these principles in the book, I regularly encourage the reader to add more interfaces to their classes, to make …
During the holiday I read a book mentioned to me by Pim Elshoff: "Skin in the game", by Nassim Nicholas Taleb. Discussing this concept of "skin in the game" with Pim had made me curious about the book. It's not such a fat book as one of Taleb's other books, which is possibly more famous, called "Antifragile". "Skin in …
Recently I read a comment on Twitter by Nikola Poša: I guess the discussion on my thread is going in the wrong direction because I left out a crucial hashtag: #NoCommentsInCode - avoid comments in code, write descriptive classes, methods, variables. https://t.co/MuHoOFXCvV — Nikola Poša (@nikolaposa) July 13, …
In "Negative Architecture" , Michael Feathers speaks about certain aspects of software architecture leading to some kind of negative architecture . Feathers mentions the IO Monad from Haskell (functional programming) as an example, but there are parallel examples in object-oriented programming. For example, by using …
Consider the following rule: When you create an object, it should be complete, consistent and valid in one go. It is derived from the more general principle that it should not be possible for an object to exist in an inconsistent state. I think this is a very important rule, one that will gradually lead …
System and integration tests need database fixtures. These fixtures should be representative and diverse enough to "fake" normal usage of the application, so that the tests using them will catch any issues that might occur once you deploy the application to the production environment. There are many different options …
A very important "trick" in finding the flow in life is: do what you like most . Of course, you have to do things you don't like (and then you need different life hacks), but when you can do something you like, you'll find that you'll be more successful at it. When it comes to blogging, I find that it helps to …
The downsides of starting with the domain model All the architectural focus on having a clean and infrastructure-free domain model is great. It's awesome to be able to develop your domain model in complete isolation; just a bunch of unit tests helping you design the most beautiful objects. And all the "impure" …
I'd like to start this article with a quote from Ross Tuck's article "Persisting Value Objects in Doctrine" . He describes different ways of persisting value objects when using Doctrine ORM. At the end of the page he gives us the following option - the "nuclear" one: [...] Doctrine is great for the vast …
Statically fetching dependencies I've worked with several code bases that were littered with calls to Zend_Registry::get() , sfContext::getInstance() , etc. to fetch a dependency when needed . I'm a little afraid to mention façades here, but they also belong in this list. The point of this article is not to bash …