Most complex tasks are solved using abstractions. To create an abstraction one groups lower-level concepts, what I will call primitives in this text, and make them interact in a pre-defined way.
Abstractions are present at all levels in a system. Computers work based on electric signals. To reduce the Essential Complexity we abstract those signals with […]
Last week, Cauê and I were refactoring some classes in our systems and faced an interesting situation.
In our application we have a notifications system. It is quite simple; notifications are read from a text file and shown in a small information box in the home page. The MVC controller –it’s a Java application and we […]
Weeks ago, some people in the Ubuntu community got a bit disappointed with the distribution’s core team:
> We are supposed to be a community, we all use Ubuntu and contribute
> to it, and we deserve some respect regarding these kind of decisions.
> We all make Ubuntu together, or is it a big lie?
We all make […]
Over the past years I’ve held many workshops on Domain-Driven Design. We had more than one hundred people on those sessions, and feedback was often pretty good. After my last run I told my business partner that this was my last time running those workshops.
I think that Domain-Driven Design is one of the most […]
We finished last post with this funny situation: the abstraction that represents Facebook depends on our Domain Model.
It was a bit obvious that what we needed was not only system abstractions for Facebook, Twitter and the like but Bounded Contexts. We need to acknowledge the fact that these domains are not part of our model, […]
Read the first post here.
In the previous post we were facing the problem demonstrated by the diagram below.
Our FacebookMessageParser needs an instance of AllSocialNetworks so that it can create valid Users coming from Facebook. The only implementation we have for the AllSocialNetworks interface is UserRepository, and this implementation needs a FacebookMessageParser. That’s a circular dependency, […]
I’ve been extremely busy with project after project in the past few months, leaving me no time to do any research and/or play around interesting things. Even though I prefer to write about what is really interesting me at a given moment, I think that writing about some smaller/simpler problems and solutions would be better […]
As I said here before I was in Brazil some weeks ago to present at a conference. I had a really great time over there with some amazing people and would like to thank Caelum for their hard work in creating such a great conference. I’m making the slide deck and notes available in my […]
After so many years I thought that this was a dead topic but recently I saw at least two reasonably experienced developers having trouble with object identity and thought that it would be good to write about it.
Most languages define some kind of equality operator on objects, in Java, for example, that is the equals […]
As a consultant I have to log my hours in a timesheet application. This could be a test inside the timesheet app:
[TestFixture]
public class BillableTimeTest
{
[Test]
public void ShouldhaveCorrectNumberOfWorkedHours()
[…]
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