Question for migrating an existing system to dartemis

[arnaud-secondlayer]

I'm trying to migrate an existing system to dartemis. The system is large enough that I have to spread the migration other several weeks/months. One problem I'm facing right now is that I started splitting my large classes data into components, but most of my code doesn't live in systems yet. In order to access the component data, I'm using mappers, but I cannot always refactor my code to benefit from mappers, and creating a mapper just to decide if an entity has one component or retrieve one field from a component is expensive.

I was wondering if it was possible to add a function to retrieve a Component? given an entity without creating a mapper. I know it will not be as fast as mappers in systems, but it should be faster when accessing data in a more randomized fashion.

[denniskaselow]

I'm not exactly sure I understand what you are trying to do.

But maybe overriding the added/deleted function of a system or manager and only add the entities with the Component/or unrefactored data and use that instead of using mappers? Though you won't be able to react to removed/added components.

Or maybe oxygen is a better fit? It has a get<Component>() function on Entity.

[denniskaselow]

Is having this function exposed what you would want: https://github.com/denniskaselow/dartemis/blob/8c8bc149231e448369108de3674548afe6e0d08a/lib/src/core/component_manager.dart#L70 (It no longer exists, but I think it should still work if I add it again).

[arnaud-secondlayer]

Yes, that's exactly the function I would need. Maybe return T?, but that's the idea.

[denniskaselow]

Ok, I'll add the function. That code was before null safety, so yeah, it'll be T?. Shouldn't take long.

[denniskaselow]

Done. Use it like this:

final componentType = ComponentType.getTypeFor(MyComponent);
final component = world.componentManager.getComponent<MyComponent>(entity, componentType);

[arnaud-secondlayer]

I think there is an issue in getComponent when entity is larger than _ComponentInfo.components or if components[entity] is null.

[denniskaselow]

Sorry about that :(.

A new version with a fix has been published. If it doesn't work and there are still exceptions, please include the stacktrace too. Thank you.