Add Dependency Injection Support for WorldGen Plugins

jdrueckert commented 2 years ago

Motivation

Dependency injection via @In is a widely used mechanism throughout our code-base. However, it doesn't seem to be supported for all kinds of classes yet.

While it is implemented for world generators, it is not yet implemented for world-gen plugins. If used for these, it can/will lead to NPEs due to fields not being properly initialized before being accessed.

Example

Typically, the pattern to get a dependency injected looks like this

@In
BlockManager blockmanager

If this fails, blockmanager will be null and result in an NPE when being accessed.

The current workaround for this issue is to get the dependency from CoreRegistry instead:

blockManager = CoreRegistry.get(BlockManager.class);

Proposal

It would be nice to support dependency injection for world-gen plugins as well. The implementation would probably look similar to how it is already implemented for world generators.

The idea is to do the following:

get all classes that are annotated with @RegisterPlugin, for instance the CaveRasterizer or the LakeProvider
fetch the annotation via <class>.getAnnotation(RegisterPlugin.class)
load the class via <class>.getConstructor(SimpleUri.class).newInstance(<annotation>.id())
perform the injection via InjectionHelper.inject(<loadedPlugin>)

Additional notes

Related Issues:

https://github.com/MovingBlocks/Terasology/issues/2336

ogkunald commented 1 year ago

Hello, Please assign this to me

vishalsingh2972 commented 1 year ago

@jdrueckert could you assign this to me if it is still open?

jdrueckert commented 1 year ago

Hi @vishalsingh2972, we typically don't assign issues to people until they at least provide a preliminary PR. So I suggest you take a stab at the issue and provide a PR with some initial changes and then we can assign it to you =)

xbdhshshs commented 1 year ago

Hi, is this issue still open?

jdrueckert commented 1 year ago

@xbdhshshs Yes it is.

xbdhshshs commented 1 year ago

Great, then can I have a go at it? I've worked with Java and SpringBoot before but haven't contributed to open source. I will go through the contributing guidelines and the motivation stated above thoroughly, but if you could guide me to the specific files/directories to be worked with, that would be really helpful...

@jdrueckert

jdrueckert commented 1 year ago

@xbdhshshs sure, you don't have to ask whether you can have a go at something :wink: To get started around here, I'd recommend having a look at our Contributor Quick Start Guide. And if you have questions you can always come talk to us on our Discord.

For the specific issue, I believe all relevant resources are already linked in the issue description. So feel free to onboard with the above mentioned guide, give the proposed solution for this issue a go and open a PR with your work (ideally as soon as possible, so we can have a look and comment on whether or not this goes into the right direction, etc.).

xbdhshshs commented 1 year ago

Thanks for the reply😁. I'll follow the guide and get on with it the issue asap.

spookynutz commented 9 months ago

Hello @jdrueckert, I'll try and have a poke at this topic if it's ok

jdrueckert commented 9 months ago

@spookynutz sure, go ahead

spookynutz commented 9 months ago

Hello @jdrueckert,

I created a first draft of the manager but it is not complete yet since I have some interrogations. I added comments on my Draft PR since I thought it would be a better place to have the discussions. If you could have a look and help me clarify so that I can proceed with the rest. Thank you !

MovingBlocks / Terasology