OO Principles: Encapsulating CFCs
I don't "do OO" development in ColdFusion. I'm starting with that statement not to spark another debate about whether to use OO in ColdFusion, but rather to clarify that while this post is about a principle of object oriented development, you don't need to "Do OO" in order to learn, use, and benefit from encapsulating CFCs.
When I first started using CFCs, I knew that encapsulation and decoupling were important, but this brought up new challenges. For example, if I had a method that queried a database, how would it know what datasource to use?
For instance, now you have the datasource encapsulated within the Users component. But you may run into some other issues. Right now Users is in application scope. Nothing wrong with that, but lets say I have a Companies service that depends on the Users service. Right now it's probably calling application.Users. Again, not a problem, but imagine you want to write a unit test for Companies. It's now a pain to test Companies in isolation as it is calling the application scope directly.
What you *really* want is for Users to be injected into Companies. That way when you write a test you can just Companies.setUsers(MockUsers) to pass in a mock or stub implementation of the Users object so you can test Companies in isolation.
Of course, the common solution to this recuring problem us a DI engine such as ColdSpring or Lightwire. But I *do* think it is important to introduce CFC's to people one step at a time, showing the problems they solve and then the next set of problems that you run into (for certain classes of problems - for others you can get away with no objects or with a step on the path).
For me, the biggest benefit of CFC's is the capacity to create granularly testable code and I have a feeling that the many people who wonder about the benefits of CFC's would get it a little more if they tried TDD. But then of course they need to decide whether there are sufficient benefits in TDD!
Thanks for the feedback. Indeed, the next posting I have planned is on composition. I started this one with the intent of writing about composition but I realized I needed to cover some more basics before I got to that.
I may eventually cover DI engines as well (I have my own that I created before Lightwire existed and before I had heard of ColdSpring which works a bit different than either of them).
I am a big fan of TDD as well. I just switched from CFUnit to MXUnit, both of which I really like.
In the meantime, I will look into making my SpamFilter a bit more forgiving. Sorry for the trouble on that.