[Feature] Allow @polymorphic on class definitions

[misha]

Related packages

dogs_core

Feature

When I have a sealed class, I have to remember to tag each usage in @serializable classes with @polymorphic. I frequently forget, and end up discovering the error at runtime when serialization breaks.

Ideally, it becomes possible to tag the class' definition with @polymorphic, or just make the class @serializable with the same intent. (I believe right now it's an error, since abstract classes cannot be instantiated.)

This also reduces lines of code across all my models since all those @polymorphic annotations are usually the only annotation on those fields.

If this is already possible, please let me know. I looked through the documentation site but didn't find a way to do it.

[helightdev]

I'd like to add support for that, but that would require some modification of the code generator since it currently treats all types are relatively opaque except for primitives - but I think I can add support for that in the future by trying to resolve the referenced type. Behaviour could vary though for types not defined the same package, I'll have to test that.

I can definitely see where this might be a bit annoying, if I add support for the type resolution, I can also directly add support for treating abstract classes as polymorphic by default.

[misha]

Having it work by default for sealed classes in particular would be fantastic, as union types are their primary use case. I don't think I have an @polymorphic on a single abstract but not sealed class. Perhaps this reduces the implementation difficulty, as sealed classes must be in the same file as far as I know.