Base class shouldn't necessarily be abstract

[carueda]

Related with #64, the base class shouldn't necessarily be abstract, but this is currently required per the issue 64b test, which refers to this spec:

    #@define
    BaseModelConfig {
      uuids: [string]
      scaling: double
    }
    
    #@define extends BaseModelConfig
    LoadModelConfig {
      modelBehaviour: string
      reference: string
    }
    
    test.loadModelConfig = LoadModelConfig

[johanneshiry]

I dunno how much time I'll have within the next few weeks to work on this, but I agree that it might make sense to support either #@define or #@define abstract. One major change that would include #@define and allow its extension would be, that we cannot use case class anymore but we would have to go with class instead, because AFAIK case class cannot be extended.

This fact has been the main motivation to use the #@define abstract instead. I assume the logic will become far more complex if we have to check first if a specific #@define is extended (then is has to be a simple class) or not (then it can be a case class). Furthermore, having this in mind we would lose benefits provided by case classes for the simple class that is extended.

[carueda]

Thanks @johanneshiry . Maybe it could be supported only for Java, at least initially. But no rush at all, I'll also try to find some time for this.