The composite pattern/entity system and traditional OOP

Question

I\'m working on a small game written in Java (but the question is language-agnostic). Since I wanted to explore various design patterns, I got hung up on the Composite pattern/E

Answer 1

It sounds like you've slightly misunderstood the component pattern.

Components are data ONLY, no code. If you have code in your component, it's not a component any more - it's something more complex.

So, for instance, you should be able to trivially share your CharacterAnimationRender and CharacterStatistics, e.g.:

CharacterStats { int BODY }
CharacterGameStats { ...not sure what data you have that affects gameplay, but NOT the rendering... }
CharacterVisualDetails { int FACE, int HAIR }

...but there is no need for these to be aware of the existence of each other. The moment you talk about "dependencies" between components, I suspet you've got lost. How can one struct of ints "depend upon" another struct of ints? They can't. They're just chunks of data.

...

Going back to your concerns at the start, that you end up with:

Alien.addComponent(new Position(), new AlienAIMovement(), new RenderAlien(), new ScriptAlien(), new Target());
Player.addComponent(new Position(), new KeyboardInputMovement(), new RenderPlayer(), new ScriptPlayer(), new PhysicsPlayer());

...that's perfect. ASSUMING you've written those components correctly, you've split out the data into small chunks that are easy to read/debug/edit/code against.

However, this is making guesses because you haven't specified what's inside those components ... e.g. AlienAIMovement - what's in that? Normally, I'd expect you to have a "AIMovement()", and then edit it to make it into an Alien's version, e.g. change some internal flags in that component to indiate it's using the "Alien" functions in your AI system.