Bold Pixel’s Namespaces and Interfaces

After much thought and discussion by myself or at the FGL chat I made some decisions about how to make Bold Pixel more modular in order to simplify my own work. Since we are still on top of contracts, I couldn’t give enough attention to this but my brain was dealing with it in the background.

Inheritance Spaghetti

The problem presented was somewhat simple. My early coding of the blit engine got tangled in the dreadful inheritance headaches. My solution to it was to create one class per major responsibility. It worked fine until the time I decided to expand one of the classes to do something it wasn’t designed to do. So on one hand I solved the inheritance problems but on the other I lost modularity. At this time I had a OOP doubt that I expressed in the FGL forums and the discussion that started there really helped me to move in a different direction, one that I had never considered.

More over I said that I would not support requests that didn’t deal with deal with real problems we had in our own development. And while I stick to that, I couldn’t help but to think: what if Bold Pixel could help someone but it missed one little tiny feature? While this was puzzling me, there was real problem, one with impact in our development that was taunting me…

The case of Blit vs Physics

So Bold Pixel has a blit engine and it will wrap a physics engine (more about the physics engine this later this month) so the question that was on top of the table was: considering there is a blit entity and a physics entity, which one should access the other? Whatever the answer was, modularity was lost in the sense I imagine it. I don’t want blit to know physics and I don’t want physics to know blit!

After a nice chat with Antriel at FGL (thanks mate!) I got to know the Strategy Pattern and all my problems were solved. In simple terms, I will be defining interfaces for all interchangeable objects but the implementations of the interfaces can exist anywhere. In the case presented, a blit entity will have its spatial properties (rotation, x, y and scale) defined by a spatial interface. By default it will be a simple class and it’s needed since the properties of the spatial interface are needed to render bitmapdata. A physics entity will be a implementation of  the spatial interface, so if I want to use physics on a blit entity, I simply write: myBlitEntity.position = myPhysicsEntity;

Visibility and Access Issues

This brought another problem. Bold Pixel has always kept its inner “stuff” hidden. The objective was this was to keep the auto-completion short and the use easy preventing mistakes. In order to implement interfaces I would have to make a lot of code public.

The answer to this would be abstract classes, but ActionScript3 does not support it. That will be addressed with simple naming and convention over configuration. Any class in any namespace in Bold Pixel that starts with Abstract will only have the simplest shortest implementation needed for something to work. For instance, if I want a blit entity that draws pixels I will have to extend a AbstractBlitEntity class (I guess that will be the name) but that brings another problem…

So ActionScript does not support abstract classes… convention will say that Abstract defines an abstract class.

Namespaces (to wrap this up!)

To have a better code organization I will need more packages and to have more packages I will need to provide access to classes in different packages. This will be done with namespaces. The only thing that annoys me is that Flash Develop in the current version (3.2.2) does not support code-completion with custom namespaces, but what matters is that using custom namespaces solves two problems. First I can have a bunch of private functionality like I like, but second, any coder can with a simple namespace use extend Bold Pixel to his own needs in a full modular way.

While I reckon that this is all just in my head and that a lot of work will have to be done and even considering that probably this will make Bold Pixel a little bit more complicated to the average coder, I feel it sorts a lot of questions, so: Namespaces and Interfaces FTW!