OOP

I’ve had a long love-hate relationship with Rails. I love the MVC framework and how it’s improved our speed of writing web apps. But I’ve never really been completely happy with it. I don’t generally agree with most of its opinions. I prefer models that follow the Data Mapper pattern, not the Active Record pattern. This includes separating the persistence layer from the models’ business logic. I prefer Slim or HAML to ERB. I prefer RSpec to Test::Unit or MiniTest. When Merb hit the scene, I was ready to make the jump, until Merb merged with Rails. ...

I created a Ruby gem recently, called includable-activerecord. It’s pretty small, but I thought I might explain why I created it, and discuss its implementation. Classical Inheritance When you use ActiveRecord, you normally include it in your model like this: class User < ActiveRecord::Base # ... end Your User class is inheriting from the ActiveRecord::Base class. This is class-based inheritance, also called “classical” inheritance. (That’s “classical” as in “class”, not as a synonym for “traditional”.) Class-based inheritance represents an “is-a” relationship. So we’re saying that a user is an ActiveRecord base. Another way to say this is that User is a subclass of ActiveRecord::Base. There are a few problems with this. First, what is a “base”? The name was chosen because it’s a base class. But just like we don’t give factory classes names like UserFactory (at least not in Ruby), we shouldn’t name base classes Base. ...

It’s challenging to test Rails custom validators. I recently had to write a validator to require that an entered date is before or after a specified date. It didn’t seem like writing the validator would be too difficult – I’ve written custom validators before, and date comparisons aren’t all that tricky. But when it came time to write the tests, I ran into several issues. And since I always try to follow TDD / test-first, I was blocked before I even began. ...