What's with the ClassInheritanceMultiMap?

[coolAlias]

Why, Mojang, would you add something like this, when Java already knows how to test for class inheritance?

// Searching for entities that implement a given interface:
List entities = world.getEntitiesWithinAABB(SomeInterface.class, player.getEntityBoundingBox().expand(radius, (double) radius / 2.0D, radius));

// Oh joy...
Caused by: java.lang.IllegalArgumentException: Don't know how to search for interface test.entity.SomeInterface
at net.minecraft.util.ClassInheritanceMultiMap.func_180212_a(ClassInheritanceMultiMap.java:53) ~[ClassInheritanceMultiMap.class:?]
at net.minecraft.util.ClassInheritanceMultiMap$1.iterator(ClassInheritanceMultiMap.java:111) ~[ClassInheritanceMultiMap$1.class:?]
at net.minecraft.world.chunk.Chunk.getEntitiesOfTypeWithinAAAB(Chunk.java:1103) ~[Chunk.class:?]
at net.minecraft.world.World.getEntitiesWithinAABB(World.java:3289) ~[World.class:?]
at net.minecraft.world.World.getEntitiesWithinAABB(World.java:3272) ~[World.class:?]

This kind of code worked perfectly fine before.

 

I'm baffled about how to use the ClassInheritanceMultiMap class; it has a public 'add(Class)' method that is never called from anywhere, and no instance of the class is ever instantiated except for within the Chunk class, and that seems to only be used to contain a list of entity classes currently in the chunk.

 

The method func_180212_a relies on Apache commons ClassUtils to return the class hierarchy; do we now have to register all of our custom classes / interfaces somehow in order for them to be recognized? What the hell is going on here?

[coolAlias]

Yeah, I could see that's what it was doing, but I couldn't believe it so I had to ask. I mean, I suppose they are saving some CPU cycles, but wtf. Surely there are other areas that would improve performance more than this.

 

Is there any way to add an interface to the mappings? Does that need to be done on a chunk-by-chunk basis as entities of that type enter the chunk, or can it be added once and be done with it?

 

Worst case scenario is to simply write a custom method specifically for interfaces that uses standard Java instanceof comparisons on all entities found within the given area.

[coolAlias]

Most impressive, as always

 

I'd say 'submit this as a bug to Mojang', but that's a lost cause. Last time I submitted a bug with an equally simple fix, it was for 1.7.2, and they dallied around the issue for 6 months and then "Oh, well it's no longer an issue because 1.8 is out now and doesn't suffer from it". Yeah, but you could have f-ing fixed it in 30 seconds 6 months ago, and then neither 1.7.2 or 1.7.10 would suffer from it either!!! Argh.

 

Anyway, I wrote a simple helper method to use in the meantime, nothing fancy:

/**
* Returns a list of all entities within the given bounding box that match the class or interface provided
*/
@SuppressWarnings("unchecked")
public static <T> List<T> getEntitiesWithinAABB(World world, Class<T> clazz, AxisAlignedBB aabb) {
List<Entity> entities = world.getEntitiesWithinAABB(Entity.class, aabb);
List<T> found = Lists.newArrayList();
Iterator<Entity> iterator = entities.iterator();
while (iterator.hasNext()) {
	Entity e = iterator.next();
	if (clazz.isAssignableFrom(e.getClass())) {
		found.add((T) e);
	}
}
return found;
}

As you can see, I just piggy-backed on the vanilla method, since it's so fast and furious, to get a base list of Entities, then cherry-pick any that match the interface (or any class) out of that.

 

It could probably be optimized better, but I didn't want to waste any more time when there is still so much of my mod that needs updating.

[Draco18s]

I'd say 'submit this as a bug to Mojang', but that's a lost cause. Last time I submitted a bug with an equally simple fix, it was for 1.7.2, and they dallied around the issue for 6 months and then "Oh, well it's no longer an issue because 1.8 is out now and doesn't suffer from it". Yeah, but you could have f-ing fixed it in 30 seconds 6 months ago, and then neither 1.7.2 or 1.7.10 would suffer from it either!!! Argh.

 

Or close it because it's a mod problem.  Like maps not functioning correctly in dimensions above 127.