Why can't a pack have a base class in its public directory for other packs to extend?

Tools RubyAtScale
1

This message was imported from the Ruby/Rails Modularity Slack server. Find more info in the import thread.

Message originally sent by slack user U71S0G4TZY5

It appears that a pack cannot define a base class in its public directory intended to be extended by other packs. When trying to do this, one sees errors, e.g. RuboCop: Public API method must be a class method (e.g. self.initialize(…)) [Packs/ClassMethodsAsPublicApis] . Can someone explain why this choice was made?

2

<@U71S0G4TZY5> this cop was an experimental one intended to push folks at Gusto to use class methods for their APIs. At this point, I don’t think it’s a super valuable cop so I’d definitely say turn it off if it’s not serving you (it should be default off).

3

Message originally sent by slack user U71S0G4TZY5

Gotcha, thanks

4

Message originally sent by slack user U70TIGAX94P

base class in its public directory intended to be extended by other [packages]
Just for context - I think it’s great to have things like ApplicationRecord public to be inherited from.

As for extension - it’s easy to underestimate the blast radius of changing the behavior of an upstream dependency, similar to the problems you can run into with monkeypatches on library code.

5

One aspect of this cop that we should probably communicate better: it is definitely not meant for all packs. Since you say “intended to be extended by other packs”, I imagine that you might think of your pack as a library. This cop makes no sense for libraries. In fact, I think it only makes sense of you imagine your pack wanting to become a separate runnable (a separate app). Only in that situation, if you squint, the cop starts enforcing something like a REST API to the pack…