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Sublinks Aims to Be a Drop-In Replacement for Lemmy (wedistribute.org)

submitted 9 months ago by [email protected] to c/[email protected]

313 comments fedilink hide all child comments

Seems like an interesting effort. A developer is building an alternative Java-based backend to Lemmy's Rust-based one, with the goal of building in a handful of different features. The dev is looking at using this compatibility to migrate their instance over to the new platform, while allowing the community to use their apps of choice.

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[–] [email protected] 15 points 9 months ago (2 children)

Here's an example:

https://github.com/sublinks/sublinks-api/blob/main/src/main/java/com/sublinks/sublinksapi/community/listeners/CommunityLinkPersonCommunityCreatedListener.java

IMO that's a lot of code (and a whole dedicated file) just to (magically) hook a global event and increase the subscriber count when a link object is added.

The worst part is that it's all copy/pasted into a neighbouring file which does the reverse:

https://github.com/sublinks/sublinks-api/blob/main/src/main/java/com/sublinks/sublinksapi/community/listeners/CommunityLinkPersonCommunityDeletedListener.java

It's not the end of the world or anything, I just think good code should surprise you with its simplicity. This surprises me with its complexity.

[–] [email protected] 3 points 9 months ago

Yeah but that's more on the coder. Like you indirectly say, they could just as well have had a single listener for community update events, since they all share the data structure for such events (I would assume, haven't looked around too much).

And to me as a professional java coder, I will say it's just not complex. The scaffolding you mentally discard after a week of working with Java unless you're looking for something related to do the scaffolding - and then it's cool that it's all explicitly there, this has helped me countless times in my career and is one of the big strengths of such verbose languages - and beyond that and some design choices I would not have made that way related to naming and organization, there's not much code there to begin with. In modern Java you might just do this in a lambda supplied in the place where you hook the events, anyways.

[–] [email protected] 3 points 9 months ago (1 children)

I find that Java is overly Verbose, but it’s much better than the alternative of underly verbose.

Java really follows the single class for single functionality principle, so in theory it makes sense to have these located in different classes. It should probably be abstracted to a shared method, but it shouldn’t be in the same file.

At least to me this looks like simplicity, but I’ve been writing Java in some capacity since 2012.

[–] [email protected] 6 points 9 months ago

It's not just the visible complexity in this one file. The point of it is to keep a subscriber count in sync, but you have that code I referenced above, plus:

LinkPersonCommunityCreatedEvent LinkPersonCommunityDeletedEvent LinkPersonCommunityCreatedPublisher LinkPersonCommunityDeletedPublisher

And then there are things like LinkPersonCommunityUpdated[Event/Publisher] which don't even seem to be used.

This is all boilerplate IMO.

And all of that only (currently) serves keeping that subscriber count up to date.

And then there's the hidden complexity of how things get wired up with spring.

And after all that it's still fragile because that event is not tied to object creation:

  @Transactional
  public void addLink(Person person, Community community, LinkPersonCommunityType type) {

    final LinkPersonCommunity newLink = LinkPersonCommunity.builder().community(community)
        .person(person).linkType(type).build();
    person.getLinkPersonCommunity().add(newLink);
    community.getLinkPersonCommunity().add(newLink);
    linkPersonCommunityRepository.save(newLink);
    linkPersonCommunityCreatedPublisher.publish(newLink);
  }

And there's some code here:

https://github.com/sublinks/sublinks-api/blob/main/src/main/java/com/sublinks/sublinksapi/api/lemmy/v3/community/controllers/CommunityOwnerController.java#L138C31-L138C50

    final Set linkPersonCommunities = new LinkedHashSet&lt;>();
    linkPersonCommunities.add(LinkPersonCommunity.builder().community(community).person(person)
        .linkType(LinkPersonCommunityType.owner).build());
    linkPersonCommunities.add(LinkPersonCommunity.builder().community(community).person(person)
        .linkType(LinkPersonCommunityType.follower).build());

    communityService.createCommunity(community);

    linkPersonCommunityRepository.saveAllAndFlush(linkPersonCommunities);

that is able to bypass the community link service and create links in the repository directly, which would presumably not trigger than event.

Maybe there's a good reason for that, but it sure looks fragile to me.